"Comment on ""Non-symmetric substituted ureas locked in an (E,Z) conformation: an unusual anion binding via supramolecular assembly"" by M. Olivari, C. Caltagirone, A. Garau, F. Isaia, M. E. Light, V. Lippolis, R. Montis and M. A. Scorciapino, New J. Chem., 2013, 37, 663"

We propose another point of view on the type of hydrogen bonded complexes that were described in this journal (M. Olivari et al., New J. Chem., 2013, 37, 663). The main difference is the molecular geometry and breakage of the intramolecular hydrogen bond during association. The current comment is to highlight mentioned aspects and to point out that in some cases the interpretation may not be straightforward due to the simultaneous effects associated with complexation.

Substituent and temperature controlled tautomerism: Multinuclear magnetic resonance, X-ray, and theoretical studies on 2-phenacylquinolines

Proton-transfer equilibria in chloroform solution of twelve 2-phenacylquinolines were studied by 1H, 13C and 15N NMR spectroscopies. The (Z)-enaminone form stabilized by an intramolecular hydrogen bond was found to prevail in all cases. Electron-donating substituents in the phenacyl part of the molecule lead to an increase of the ketimine form (to 33% for p-NMe2). Variable temperature 1H NMR measurements show that higher temperatures have the same effect. The negative logarithm values of the equilibrium constant, pKT, were found to be linearly dependent on Hammett σ substituent constants. The pKTvs. temperature correlation also has a linear character. In general, strong electron-withdrawing…

Substituent effects on13C NMR parameters of chlorinated diphenyl ethers. A multiple linear regression analysis

13C NMR chemical shifts and nJ(C,H) coupling constants of polychlorinated diphenyl ethers (PCDEs) were measured and analysed. The chlorine substituent effects on the chemical shifts and the coupling constants were determined by a multiple linear regression analysis. The 13C NMR chemical shifts depend on the conformational preferences in PCDEs. In addition to single substituent effects, corrective terms reflecting the conformational state of the molecule and the mutual steric interactions of two chlorine atoms had to be taken into account for the reliable prediction of the 13C chemical shifts. In contrast to chemical shifts, conformational effects play a minor role in the substituent effects…

NMR crystallography of 2-Acylamino-6-[1H]pyridones: solid state NMR, GIPAW computational, and single crystal X-ray diffraction studies

Abstract 2-Acylamino-6-[1H]-pyridones [acyl = RCO, where R = methyl (1), ethyl (2), iso-propyl (3), tert-butyl (4), and 1-adamantyl (5)] have been synthesized and characterized by NMR spectroscopy. From three congeners, 2, 3 and 5, also single crystal X-ray structures have been solved. For these derivatives GIPAW calculations acts as a “bridge” between solid-state NMR data and calculated chemical shifts based on X-ray determined geometry. In crystals all three compounds exist as pyridone tautomers possessing similar six-membered ring structure stabilized by intramolecular C O⋯HN hydrogen bond. Theoretical GIPAW calculated and experimental 13C and 15N CPMAS NMR shifts are in excellent agreem…

Resorcarenes in the Boat Conformation as Building Blocks for Hydrogen-Bonded Assemblies Including Two Ammonium Cations

Crystal structures are reported for various co-crystals of rccc-resorcarenes with triethylammonium chloride. Usually, two molecules of a C2v-symmetric tetraester 2 in the boat conformation are linked through four hydrogen-bonded chloride anions to give dimeric assemblies. Two of the chloride anions may be replaced by four hydrogen-bonded ethanol molecules in an otherwise similar structure. These assemblies, which consist of six or eight components, posses voluminous, negatively charged chambers in which two triethylammionium cations, 3+, are included as guests by strong electrostatic and hydrogen-bonding interactions. The host-guest N-H...Cl hydrogen bonds were clearly detected at 173 K. Th…

13C NMR Spectral Identification of Four Cyclolithocholates (3α-Hydroxy-5β-cholan-24-oate Macrolides)

17O NMR study of isomeric monochloro- and monohydroxy-benzaldehydes and chlorinated salicylaldehydes

The 17O NMR chemical shifts of isomeric monochloro- and monohydroxy-benzaldehydes and chlorinated salicylaldehydes were measured at 40°C for 0.25 M CDCI3 solutions. The 17O NMR chemical shift of the carbonyl oxygen of the compounds studied varies from 506 to 573 ppm measured from external D2O. The observed variation is probably mainly due to the intramolecular hydrogen bonding between the adjacent carbonyl and hydroxyl groups. The 17O NMR chemical shift range of the hydroxyl oxygen is from 80 to 98 ppm.

13C and15N NMR study of substituted 1,2,4-triazines

13C and 15N NMR spectra of eight substituted 1,2,4-triazines were measured and assigned. The assignments of the 13C NMR spectra were based on the substituent chemical shifts and nJ(C,H) coupling constants. 15N NMR chemical shifts generally showing well separated ranges were assigned by the proton coupled 15N NMR spectra. 15N NMR chemical shifts of N-4 in 3- and 5-methoxy or -thiomethyl-substituted 1,2,4-triazines were found to be related significantly (confidence level >99%) with the π-charge at N-4 calculated by a semi-empirical molecular orbital (AM1) procedure. For the 15N NMR chemical shifts of N-1 and N-2, no reliable correlations with the molecular electronic properties such as AM1 π-…

NMR studies of benzoannulation in lithium, sodium and potassium ortho-formylphenolates

Abstract Lithium, sodium and potassium derivatives of (benzo)salicylaldehydes have been prepared and characterized by 1 H and 13 C NMR in order to see how the metal cation and benzoannulation affect spectral parameters. There is no qualitative effect of the alkali metal atom in the compounds studied (from this point of view salicylaldehydes remind β-diketones). On the other hand, 1 H chemical shifts of the hydroxyl and formyl protons and 13 C chemical shifts of C2 (bearing OX, X = H, Li, Na or K) and of that the formyl carbon show the most significant variations being the best indicators of aromatic character of the six-membered quasi-ring of salicylaldehyde. In contrast, C1 (bearing formyl…

Difference in the behavior of methyl (S)-?-bromopropionate in its addition to trimethylvinylsilane depending on the method of initiation

The addition of methyl (S)-2-bromopropionate to trimethylvinylsilane initiated by systems based on iron pentacarbonyl affords a racemic adduct and is accompanied by racemization of the unreacted chiral ester. In the presence of benzoyl peroxide, the reaction proceeds similarly, but no racemization of the starting chiral ester occurs.

Facile synthesis of 5β-cholane-sym-triazine conjugates starting from metformin and bile acid methyl esters: Liquid and solid state NMR characterization and single crystal structure of lithocholyl triazine

Abstract Four bile acid-triazine conjugates: N2′,N2′-dimethyl-6′-(3α-hydroxy-5β-24-norcholyl)-1′,3′,5′-triazine-2′,4′-diamine (lithocholyl triazine, 4a), N2′,N2′-dimethyl-6′-(3α,7α-dihydroxy-5β-24-norcholyl)-1′,3′,5′-triazine-2′,4′-diamine (chenodeoxycholyl triazine, 4b), N2′,N2′-dimethyl-6′6′-(3α,12α-dihydroxy-5β-24-norcholyl)-1′,3′,5′-triazine-2′,4′-diamine (deoxycholyl triazine) (4c), and N2′,N2′-dimethyl-6′-(3α,7α,12α-trihydroxy-5β-24-norcholyl)-1′,3′,5′-triazine-2′,4′-diamine (cholyl triazine) (4d) have been prepared and characterized by liquid and solid state NMR. An improved synthetic method produced better yields and an easier purification procedure for 4d than reported in the liter…

13C NMR spectral assignments of 3α,3′α-bis(arylcarboxy)-5β-cholan-24-oic acid ethane-1,2-diol diesters: new lithocholic acid-based molecular clefts

3α,3′α-Bis(arylcarboxy)-5β-cholan-24-oic acid ethane-1,2-diol diesters (1–3) were synthesized by the reaction of an aroyl chloride (aroyl=2,6-dichlorobenzoyl, 2-naphthoyl and 1-pyrenoyl) with lithocholic acid (3α-hydroxy-5β-cholan-24-oic acid) ethane-1,2-diol diester. The 13C NMR chemical shift assignments of the formed molecular clefts 1–3, pyrene-1-carboxylic acid methyl ester (4) (used as model compound) and 1-pyrenoyl chloride (5) are based on literature data and 13C DEPT-135, 1H,13C HMQC and 1H,13C HMBC experiments. The molecular weights of 1–3 were determined by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Copyright © 1999 John Wiley & Sons, Ltd.

ortho-Substituent effects inN-arylacetamides. NMR and molecular mechanics investigation

1H, 13C, 15N and 17O NMR spectra of N-phenylacetamide (acetanilide) and 21 ortho-substituted acetanilides were measured and assigned. The observed NMR parameters are related to the Hammett substituent parameters and conformational characteristics of the acetamido moiety estimated by molecular mechanics calculations. Significant relationships were found for the 13C NMR chemical shifts of C-5 (para to substituent) and the direct spin–spin coupling constant, 1J(C, H), of C-3 (ortho to substituent) with Hammett substituent parameters. For 15N NMR chemical shifts of the amido nitrogen, no general correlation with the Hammett substituent parameters was found. The interactions between functionalit…

ChemInform Abstract: Chemometrics: An Important Tool for the Modern Chemist, an Example from Wood-Processing Chemistry.

This study briefly outlines the idea of principal component analysis and cross-correlation calculations (applied chemometrics) and presents an illustrative example from wood-processing chemistry. The applicability of chemometric data analysis was demonstrated by investigating the various structural changes that take place in dissolved and degraded lignin ("kraft lignin") during laboratory-scale kraft pulping of Scots pine (Pinus sylvestris) and silver birch (Betula pendula). The structural data (31P NMR and size exclusion chromatographic data) on kraft lignin were further processed by chemometric multivariate techniques (PCA and 2DCC), confirming, for example, that the cleavage of beta-aryl…

Transition to Reinforced State by Percolating Domains of Intercalated Brush-Modified Cellulose Nanocrystals and Poly(butadiene) in Cross-Linked Composites Based on Thiol-ene Click Chemistry

The classic nanocomposite approach aims at percolation of low fraction of exfoliated individual reinforcing nanoscale elements within a polymeric matrix. By contrast, many of the mechanically excellent biological nanocomposites involve self-assembled and space-filled structures of hard reinforcing and soft toughening domains, with high weight fraction of reinforcements. Here we inspect a new concept toward mimicking such structures by studying whether percolation of intercalated domains consisting of alternating rigid and reinforcing, and soft rubbery domains could allow a transition to a reinforced state. Toward that, we present the functionalization of rigid native cellulose nanocrystals …

Structural study of ethyl 3-arylcarbamoyl-2,3-diazabicyclo[2.2.1]hept-5-ene-2-carboxylates: conformation and transmission of substituent effects across the diazabicycloheptene ring

Nine new ethyl 3-arylcarbamoyl-2,3-diazabicyclo[2.2.1]hept-5-ene-2-carboxylates were prepared by a [4 + 2] cycloaddition and their FTIR, 1H, 13C and 15N NMR spectra were measured and assigned. Single crystals were grown for five compounds and their X-ray data were obtained. The electronic structure and the conformations were calculated by the semi-empirical AM1 method. Using correlations between the spectral, empirical and theoretical structural data, the transmission of substituent effects and the preferential conformation connected with the consecutive double nitrogen inversion and regarding the mutual orientation of NH and CO bonds were investigated. The results are compared with those f…

On the divide between animate and inanimate

Vitalism was abandoned already for a long time ago, yet the impression that animate beings differ in some fundamental way from inanimate objects continues to thrive. Here, we argue that scale free patterns, found throughout nature, present convincing evidence that this demarcation is only imaginary. Therefore, all systems ought to be regarded alike, i.e., all are consuming free energy in least time. This way evolutionary processes can be understood as a series of changes from one state to another, so that flows of energy themselves naturally select those ways and means, such as species and societies or gadgets and galaxies to consume free energy in the least time in quest of attaining therm…

First bisphosphonate hydrogelators: potential composers of biocompatible gels

Recently, investigation of hydrogels has gained ever increasing attention mostly because of their biomedical and pharmaceutical properties, and novel hydrogelators are constantly studied to find functional applications. Bisphosphonates (BPs) are well-known compounds applicable in different fields but are mostly used in clinics as drugs for bone-related diseases. In this study, a novel class of BP-hydrogelators together with a BP-organogelator was found, and the gelating abilities of the compounds were studied. Several techniques to analyze the structure and the properties of the formed gels were used, including solid state 13C and 31P CPMAS and solution state NMR spectroscopy, IR spectrosco…

Cyclic dipeptides: catalyst/promoter-free, rapid and environmentally benign cyclization of free amino acids

“The best catalyst is no catalyst.” With growing public concern over global warming and the amount of greenhouse gases, it is important to reduce the amount of chemicals and eliminate waste, to obtain better results in a simple, selective, safe, and environmentally benign fashion compared to conventional tedious chemical synthesis. Herein, we disclose an environmentally benign, rapid, catalyst/promoter/coupling reagent-free cyclization procedure of free amino acids to furnish exclusively cyclic dipeptides (2,5-diketopiperazines, DKPs) in excellent or even quantitative yield, along with their solid state self-assembling properties. This process is extremely simple and highly efficient with l…

13C NMR Spectral Characterization of 4-Aryl-Substituted Bispyrazolo[3,4-b;4′,3′-e]pyridines

Substituent effects of1H NMR parameters of chlorinated diphenyl ethers. A statistical approach

The 1H NMR spectra of 64 polychlorinated diphenyl ethers (PCDEs) were measured and assigned. Multiple linear regression analysis was used to estimate the effects of chlorine atoms on the 1H NMR chemical shifts and coupling constants. The ‘simple sum rules’ were found to be inadequate for the prediction of 1H NMR chemical shifts of PCDEs. Therefore, corrective terms of two chlorine atoms were taken into account. The most important effects on chemical shifts were shown to be the steric interactions of two adjacent chlorine atoms and the intramolecular ring current effect observed in the ortho-proton of tri-ortho-substituted PCDEs. The substituent effects on J(HH) coupling constants were found…

Complete Spectral Analysis of the1H NMR 16-Spin System of β-Pinene

The complete analysis of the 1H NMR spectrum of β-pinene, (1S)-(-)-6,6-dimethyl-2-methylenebicyclo[3.1.1]heptane, which is of the ABCDEFGHIJX3Y3 type, is reported and earlier results are corrected. The vicinal coupling constants, 3J(H,H), are compared with the theoretical values calculated by using the Altona and co-workers’ equations for the structure derived by molecular modelling. The results were applied to the conformational analysis of β-pinene. © 1997 John Wiley & Sons, Ltd.

?-Phenylsulfonyl-N-arylacetamides (?-phenylsulfonylacetanilides):1H,13C and15N NMR spectral characterization

Dual Substituent Parameter Modeling of Theoretical, NMR and IR Spectral Data of 5-Substituted Indole-2,3-diones

Correlations of AM1 and PM3 theoretical data, 13C-NMR substituent chemical shifts (13C-SCS) and IR carbonyl group wave numbers [ν(C3â•ÂO)] were studied using dual substituent parameter (DSP) models for 5-substituted indole-2,3-diones. For the C7 atom a reverse substituent effect attributed to extended À-polarization was observed. On the other hand, the DSP approaches for the C3 atom showed normal substituent effects with some contribution of reverse effect supported strongly by 13C-SCS correlations. In the ν(C3â•ÂO) and p(C3â•ÂO) DSP correlations the field effect contribution predominates over the resonance effect, which justifies the using of earlier suggested vibrational cou…

N2,N2.N6,N6-Tetrakis(perfluorobenzoyl)-2,6-diaminopyridine

The title compound, C³³H³F²⁰N³O⁴, is a highly fluorinated organic imide that was isolated as an unexpected product from the reaction of 2,6-diaminopyridine with 2,3,4,5,6-pentafluorobenzoyl chloride in a 1:2 molar ratio. The molecule is located on a twofold axis and one of its symmetry-independent 2,3,4,5,6-pentafluorobenzoyl groups is disordered over two sets of sites, the occupancy of the major component being 0.773 (3). In the major component, the dihedral angle between the perfluorophenyl groups is 63.64 (10)°, and these groups form dihedral angles of 67.14 (7) and 21.1 (2)° with the pyridine core. Short intermolecular C-HO and C-H...N contacts are found in the crystal structure. peerRe…

Two (E)-2-({[4-(dialkylamino)phenyl]imino}methyl)-4-nitrophenols.

The slow evaporation of analytical NMR samples resulted in the formation of crystals of (E)-2-({[4-(dimethylamino)phenyl]imino}methyl)-4-nitrophenol, C15H15N3O3, (I), and (E)-2-({[4-(diethylamino)phenyl]imino}methyl)-4-nitrophenol, C17H19N3O3, (II). Despite the small structural difference between these twoN-salicylideneaniline derivatives, they show different space groups and diverse molecular packing. The molecules of both compounds are close to being planar due to an intramolecular O—H...N hydrogen bond. The 4-alkylamino-substituted benzene ring is inclined at an angle of 13.44 (19)° in (I) and 2.57 (8)° in (II) with respect to the 4-nitro-substituted phenol ring. Only very weak intermole…

Multinuclear magnetic resonance and x-ray diffraction studies of aminonitropyridines

The 15N NMR spectra for 21 aminonitropyridines were measured and their chemical shifts assigned. The 1H and 13C NMR chemical shifts and spin–spin coupling constants were also determined for 16 compounds of this series. In order to relate the structural properties of nitramino groups and their 15N NMR chemical shifts in 2- and 4-nitramino-3-nitropyridines, which differ remarkably from all other amino groups studied, low-temperature 1H NMR, 17O NMR, comparative INEPT and IR spectroscopic studies were carried out. In addition, the x-ray crystal structure of 2-nitramino-3-nitropyridine was determined. Comparative spectroscopic studies showed that the nitramino derivatives exhibit different char…

NMR spectral and X-ray structural investigation of 1,3-bis(2-quinolyl)-2-(p-chlorophenyl)-2-propanol

Abstract 1,3-Bis(2-quinolyl)-2-(p-chlorophenyl)-2-propanol (BQCP) has been prepared and characterised by 1H, 13C, 15N NMR spectral and X-ray structural parameters. The methylene protons of BQCP are diastereotopic in solution (CDCl3) as revealed by 1H NMR. In crystalline state there exists an intramolecular hydrogen bond O–H⋯N with one of two nitrogen atoms in BQCP. Variable temperature 1H NMR and PFG 1H, 15N HMBC runs show that in solution BQCP shows C2v-symmetry (both CH2-2-quinolyl fragments are equivalent) in NMR-time scale due to a fast exchange of the hydrogen bond from one nitrogen to the other even at 223 K.

Use of Bile Acids in Pharmacological and Supramolecular Applications

Bile acid-based structures have become increasingly important in different fields of chemistry over recent years, having found applications in pharmacology, supramolecular chemistry and nanoscience. Some interesting studies concerning these applications are reviewed, together with the latest developments in synthetic and analytical methods for bile acid-derived frameworks. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

1H, 13C NMR spectral and single crystal structural studies of toxaphene congeners. Quantum chemical calculations for preferred conformers of 2,5-endo,6-exo,8,9,9,10,10-octachloro-2-bornene and their DFT/GIAO 13C chemical shifts

Abstract The 1H and 13C NMR chemical shifts for six toxaphene congeners: 2-exo,3-endo,6-exo,8,9,10-hexachloro- (1), 2-exo,3-endo,5-exo,9,9,10,10-heptachloro- (2), 2-exo,3-endo,6-exo,8,9,10,10-heptachloro- (3), 2-exo,3-endo,5-exo,6-endo,8,9,10-heptachloro- (4), 2-exo,3-endo,5-exo,6-endo,8,9,9,10-octachlorobornane (5) and 2,5-endo,6-exo,8,9,9,10,10-octachloro-2-bornene (6) are reported. Their chemical shift assignments have been obtained by means of Pulsed Field Gradient (PFG) Double Quantum Filtered (DQF) 1H,1H correlation spectroscopy (COSY), PFG 1H,13C Heteronuclear Multiple Quantum Coherence (HMQC) and PFG 1H,13C Heteronuclear Multiple Bond Correlation (HMBC) experiments. A single crystal…

119Sn-NMR Study on Bis(Tri-Butyltin)oxide Derivatives of Phenolic Compounds

Abstract 119Sn-NMR spectroscopy has been utilized in the characterization of various phenolics as their bis(tri-butyltin)oxide, TBTO, derivatives. The present method has been applied both for determination of simple model compounds and for characterization of complex biopolymeric material originating from spent bleach liquor fractionated by an ultrafiltration technique. Based on the large range of 119Sn-NMR chemical shifts of TBTO derivatives of the phenolic compounds and the similar relaxation properties of 119Sn nuclei located in those derivatives, both qualitative and quantitative analytical conclusions can be drawn.

Crystallization, spectral, crystallographical, and thermoanalytical studies of succinobucol polymorphism.

Four different polymorphs, A, C, D, and E, of succinobucol were isolated and characterized by means of solid-state nuclear magnetic resonance spectroscopy, single crystal and powder X-ray diffraction, differential scanning calorimetry, thermogravimetry, and attenuated total reflection–infrared spectroscopy. From a number of experiments, the same polymorphs (C, D, and E) and an equilibrium phase mixture B consisting of polymorphs C and D were repeatedly gained using different solvents or their mixtures. Although polymorph A was obtained directly from recrystallization only on few occasions, polymorphs C, D, and E proved to be metastable kinetic polymorphs, which slowly transform to a thermod…

1H, 13C and 17O NMR spectral study of chlorinated 3,4-dihydroxybenzaldehydes (protocatechualdehydes)

Abstract Chlorinated 3,4-dihydroxybenzaldehydes have been studied by means of 1 H, 13 C and 17 O NMR spectroscopy. The 1 H and 13 C NMR spectral assignments are based on 2-dimensional 13 C- 1 H chemical shift correlation spectroscopy (COSY). The 17 O NMR measurements at natural isotope content in organic solvents are problematic owing to the poor solubility of the compounds and/or broadness of the resonance lines. In aqueous alkaline solutions, however, all protocatechualdehydes exhibit “easy-to-detect” 17 O NMR spectral characteristics. The 17 O NMR chemical shifts in the range of 140–480 p.p.m. are interpreted as arising from the different canonical structures of formyl substituted phenol…

Comparative multinuclear magnetic resonance spectroscopic study of transition metal (Cr, W and Mn) mesitylene tricarbonyls and transition metal (Ru and Co) carbonyl clusters

Abstract Three mononuclear 1,3,5-trimethylbenzene (mesitylene) carbonyl transition metal complexes, mesitylene tricarbonyl chromium, (CH 3 ) 3 C 6 H 3 Cr(CO) 3 ( 1 ), mesitylene tricarbonyl tungsten, (CH 3 ) 3 C 6 H 3 W(CO) 3 ( 2 ), mesitylene tricarbonyl manganese tetra-fluoroborate, [(CH 3 ) 3 C 6 H 3 Mn(CO) 3 ]BF 4 ( 3 ); and three clusters, mesitylene nonacarbonyl tetracobalt, (CH 3 ) 3 C 6 H 3 Co 4 (CO) 9 ( 4 ), mesitylene carbido tetradecacarbonyl hexaruthenium, (CH 3 ) 3 C 6 H 3 Ru 6 C(CO) 14 ( 5 ) and carbido heptadecacarbonyl hexaruthenium, Ru 6 C(CO) 17 ( 6 ), have been studied by means of 1 H, 13 C and natural abundance 17 O NMR spectroscopy. Generally, the 1 H and 13 C NMR chemi…

Intramolecular cyclization of chloral allyl hemiacetal under the action of the Fe(CO)5-DMF system

Chloral allyl hemiacetal undergoes cyclization in the presence of the Fe(CO)5-DMF system to form 3,3,5-trichloro-2-hydroxytetrahydropyran rather than a butyrolactone derivative.

Concave π-prismand hydrocarbon [2.2.2]cyclophanes and their crystalline Ag-triflate complexes

New small concave hydrocarbon cyclophanes were prepared via the well-known HD-2SO2-method. The cyclophanes obtained are isomers of the very well-known [2.2.2]p,p,p-cyclophane, C24H24, a π-prismand efficiently complexing Ag+-ion. X-ray crystal structure determinations showed the bis-sulfide 7 (1,10-dithia[3.3.2]m,p,p-cyclophane) to be helically chiral and that the conformation of the parent hydrocarbon cyclophane 13 ([2.2.2]m,p,p-cyclophane) does not change dramatically upon complexation with the Ag+-ion. The 16- and 17-membered [2.2.2]m,m,p- and [2.2.2]m,p,p-cyclophane (15 and 16) also act as π-prismands and form surprisingly similar crystalline 1:1 Ag-triflate complexes (π-prismates) as th…

New qsar models for polyhalogenated aromatics

Electronic properties of polychlorinated dibenzo p dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), and polychlorinated diphenyl ethers (PCDEs) were calculated using the semi-empirical AM1 method The calculated electronic descriptors — the energy of the lowest unoccupied molecular orbital (ELUMO), the energy of the highest occupied molecular orbital (EHOMO), the ELUMO-EHOMO gap (dE), and molecular polarizability — are related to the Ah receptor binding affinity values of PCDDs, PCDFs, and PCBs and immunotoxicity values for PCDEs The quantitative structure activity relationships (QSARs) based on chlorine substitution patterns were also constructed, an…

Synthesis, NMR spectral and single crystal X-ray structural studies on Ni(II) dithiocarbamates. Fabrication of nickel sulfide nanospheres by the solvothermal method

Abstract Three dithiocarbamatonickel(II) complexes, [Ni(bzbudtc)2] (1), [Ni(bzbudtc)(PPh3)(NCS)] (2) and [Ni(bzbudtc)(PPh3)(CN)] (3) (where, bzbudtc = the N-benzyl-N-butyldithiocarbamato anion and PPh3 = triphenylphosphine), were prepared. All three complexes were analyzed by UV–Vis, IR and NMR (1H, 13C and 31P) spectra. The 13C NMR spectra of complexes 1–3 show the most crucial thioureide signal at around 200 ppm. A significant deshielding observed for the 31P signals in 2 and 3 reveals the effective bonding of phosphorus to the metal center. Single crystal X-ray analysis of crystals of 1–3 show that all the described complexes exhibit a distorted square planar coordination geometry in the…

1H,13C and17O NMR study of substituted nitropyridines

1H, 13C and 17O NMR spectra for 22 substituted nitropyridines were measured and their 1H NMR spectra were analysed. The most significant variations in the NMR parameters are found for isomeric hydroxy derivatives, owing to the possibility of keto–enol tautomerism. The prevalence of the keto form is observed in 2- and 4-hydroxy derivatives, while the 3-hydroxy derivative exists in its enol form. Among the three nuclei studied, 17O seems to be the best nucleus for probing the keto–enol tautomerism. No correlation is observed between the torsion angle of the nitro group and its 17O NMR chemical shift. Molecular mechanics calculations were performed to clarify the torsional energetics of the ni…

2-Acylamino-6-pyridones: breaking of an intramolecular hydrogen bond by self-association and complexation with double and triple hydrogenbonding counterparts. Uncommon steric effect on intermolecular interactions

2-Acylamino-6-pyridones (acyl = RCO, where R = Me, Et, i-Pr, t-Bu, and 1-adamantyl) were previously characterized by X-ray diffractometry and solid-state NMR techniques by us. One of these compounds was used recently in organocatalysis. The series is now studied in solution and by computational methods recommended for noncovalent interactions (DFT/M05). These compounds showed interesting behavior during dilution and titration experiments monitored by (1)H NMR. 2-Acylamino-6-pyridones change their conformation at higher concentrations, forming double hydrogen-bonded dimers and trimers in which an uncommon steric effect is observed. To the best of our knowledge, this is the first example of s…

1H,13C,17O and19F NMR spectroscopic study of isomeric ring-substituted monofluoro-(E)-3-phenylpropenals

Isomeric ring substituted monofluoro-(E)-3-phenylpropenals (cinnamaldehydes) were synthesized in order to provide, with the NMR-active 19F nucleus, an insight into the influence of substituents and the transmission of electronic effects between the aromatic ring and the side-chain. Their 1H, 13C and 17O NMR chemical shifts and their nJ(H,H), nJ(H,F), nJ(C,H) and nJ(C,F) values were determined. Generally, the nJ(C,F) coupling constants correlate with the length of the coupling route and thus simplify the assignments of the 13C NMR spectra. Only the side-chain carbons C-2 and C-3 in the ortho-substituted compounds showed an exception to this rule. Many long-range nJ(H,F) (n = 4–7) values were…

Syntheses of Some Biologically Active Compounds from Stilbenes Isolated from the Bark ofPicea abies

From the four stilbenes 1–4 isolated from the bark of Picea abies seven compounds 5–11 were obtained by hydrogenation or permethylation. 1H-, 13C-NMR and mass spectra were used for their characterization. The antileukemic activity of each compound was preliminary tested. Some compounds were further tested for their anti-HIV activity.

15N NMR studies of tautomerism

The literature related to 15N NMR studies of tautomerism is updated and discussed. The 15N NMR data show that the technique is applicable for both liquid and solid state (both crystalline and amorphous) materials. Modern computational methods combined with experimental NMR data can aid in the chemical shift assignments especially in case of crystalline materials (so-called NMR crystallography). This review article is divided into chapters based on the different classes of compounds and a brief description of experimental and computational NMR techniques is also included.

Phase selective synthesis of ZnS nanoparticles from structurally new dithiocarbamate precursor

Abstract A phase selective solvothermal synthesis of ZnS (wurzite) nanoparticles with a flower-like morphology using a dithiocarbamate precursor, [Zn(4-dpmpzdtc)2(dpmpz)] (1) (where, dpmpz=(diphenylmethyl)piperazine), is described. The nanoparticles were identified as ZnS (wurzite) with the particle size of about 3 to 10 nm by scanning and transmission electron microscopy as well as powder X-ray diffraction (XRD). In addition, the precursor complex 1 was characterized using single crystal X-ray diffraction.

High-Resolution Solid-State NMR Spectroscopy of Steroids and Their Derivatives

Abstract: Steroids are an important class of organic compounds containing a vast array of biologically and physiologically essential molecules. Due to their availability, relatively straightforward derivatizability, and endogeneity, they are widely used in pharmacological applications. The investigation of molecular and physicochemical properties of active pharmaceutical ingredients (APIs) in the solid state is important, because these properties are directly related to their pharmacological activity. Several methods are available for this purpose. Solid-state NMR spectroscopy offers a nondestructive and flexible technique, providing both structural and dynamic information. It can be applie…

GIAO/DFT 13C NMR Chemical Shifts of 1,3,4-Thiadiazoles

1 H, 13 C and 15 N NMR spectra of 2-acetylamino-1,3,4-thiadiazole and its 5-substituted derivatives have been measured and assigned based on reference data, as well as homo- and heteronuclear 2 D NMR experiments. In addition, the GIAO/DFT approach at the B3LYP level of theory using the 6-311G basis set was used to calculate the 13 C NMR chemical shifts. Although this method gives reliable results for 2-arylhydrazones of 1,3-diphenylpropanetrione, 2-phenacylpyridines, (Z)-2-(2-hydroxy-2-phenylvinyl)pyridines, 4-fluoroanilines, (1Z,3Z)-1,4-di(pyridin-2-yl)buta-1,3-dienediols and their tautomeric forms, the calculated chemical shifts for the 1,3,4-thiadiazoles studied are less satisfactory. Pr…

Horseradish peroxidase-catalyzed oxidation of chlorophyll a with hydrogen peroxide

Horseradish peroxidase was verified to catalyze, without any phenol, the hydrogen peroxide oxidation of chlorophyll a (Chl a), solubilized with Triton X-100. The 13(2)(S) and 13(2)(R) diastereomers of 13(2)-hydroxyChl a were characterized as major oxidation products (ca. 60%) by TLC on sucrose, UV-vis, (1)H, and (13)C NMR spectra, as well as fast-atom bombardment MS. A minor amount of the 15(2)-methyl, 17(3)-phytyl ester of Mg-unstable chlorin was identified on the basis of its UV-vis spectrum and reactivity with diazomethane, which converted it to the 13(1),15(2)-dimethyl, 17(3)-phytyl ester of Mg-purpurin 7. The side products (ca. 10%) were suggested to include the 17(3)-phytyl ester of M…

Synthesis and structural studies on Ni(II) dithiocarbamates : Exploring intramolecular Ni···H-C interactions

Five new Ni(II) dithiocarbamates with NiS4, NiS2PN and NiS2PCl coordination spheres, viz. [Ni(bupmbzdtc)2] (1), [Ni(bupmbzdtc)(PPh3)(NCS)] (2), [Ni(bupmbzdtc)(PPh3)Cl] (3), [Ni(4-dpmpzdtc)(PPh3)Cl] (4) and [Ni(pbbzbudtc)(PPh3)(NCS)] (5), where bupmbzdtc = N-butyl(p-methylbenzyl)dithiocarbamato anion, 4-dpmpzdtc = 4-(diphenylmethyl)piperazinecarbodithioato anion, pbbzbudtc = N-(p-bromobenzyl)butyl-dithiocarbamato anion and PPh3 = triphenylphosphine, were synthesized and characterized by UV, IR, NMR and single crystal X-ray diffraction methods. Spectral results suggest a square planar geometry around the Ni(II) metal center for all the synthesized complexes. Single crystal X-ray structural an…

(1Z,3Z)-3-[Quinolin-2(1H)-ylidene]-1-(quinolin-2-yl)prop-1-en-2-ol: An unexpected most stable tautomer of 1,3-bis(quinolin-2-yl)acetone

Abstract 1 H, 13 C and 15 N NMR spectra reveal that CDCl 3 solution of 1,3-bis(quinolin-2-yl)acetone contains only ( 1Z , 3Z )-3-[quinolin-2(1 H )-ylidene]-1-(quinolin-2-yl)prop-1-en-2-ol. The proton transfer takes place between two basic centers of the molecule, which means that the process is an identity reaction by character. The situation is completely different from that detected in chloroform solution of 1,3-bis(pyridin-2-yl)acetone where three different tautomers are in equilibrium with each other. Although the proton transfers in both ( 1Z , 3Z )-3-[quinolin-2(1 H )-ylidene]-1-(quinolin-2-yl)prop-1-en-2-ol and ( 1Z , 3Z )-3-hydroxy-1-[quinolin-2(1 H )-ylidene-4-quinolin-2-yl]but-3-e…

Generic Method for Modular Surface Modification of Cellulosic Materials in Aqueous Medium by Sequential Click-Reaction and Adsorption

A generic approach for heterogeneous surface modification of cellulosic materials in aqueous medium, applicable for a wide range of functionalizations, is presented. In the first step, carboxymethyl cellulose (CMC) modified with azide or alkyne functionality, was adsorbed on a cellulosic substrate, thus, providing reactive sites for azide–alkyne cycloaddition click reactions. In the second step, functional units with complementary click units were reacted on the cellulose surface, coated by the click-modified CMC. Selected model functionalizations on diverse cellulosic substrates are shown to demonstrate the generality of the approach. The concept by sequentially combining the robust physic…

Gelation behavior of 5-chloro-8-hydroxyquinoline, an antituberculosis agent, in aqueous alcohol solutions

It was shown that 5-chloro-8-hydroxyquinoline, an antituberculosis agent, gels aqueous alcohol solutions efficiently. Thermal stability and gel-to-sol transition temperature of 1% gel in CD3OD/D2O (2:1) was studied by 1H-NMR. Fibrous structures of four xerogels have been characterized by scanning electron microscope. peerReviewed

Predominance of inductive over resonance substituent effect on33S NMR chemical shifts of 4-substituted phenyl-4′-methylphenacyl sulfones

33S NMR chemical shifts have been determined for the first time for a series of 10 substituted phenacyl sulfones. Electron-withdrawing and electron-releasing substituents in 4-substituted phenyl-4′-methylphenacyl sulfones, p-MeC6H4COCH2SO2C6H4R-p, cause a ‘reverse’ substituent effect on the 33S NMR resonance. Dual-substituent parameter (DSP) analysis of δ(33S) values revealed that the inductive effect of the substituent predominates over its resonance effect. This finding shows that the 33S NMR chemical shifts are of importance in estimating the electronic properties of sulfur-containing compounds. The 13C and 17O NMR chemical shifts of the title compounds are also discussed. Copyright © 19…

Influence of Substituent and Benzoannulation on Photophysical Properties of 1-Benzoylmethyleneisoquinoline Difluoroborates

A series of 1-benzoylmethyleneisoquinoline difluoroborates were synthesized, and their photophysical properties were determined. The effect of the substituent and benzoannulation on their properties was investigated to make a comparison with recently published results focused on related quinolines. The photophysical properties of isoquinoline derivatives differ from those of quinolines, and the most pronounced differences are found for the fluorescence quantum yields. Both experimental and theoretical approaches were used to explain the observed photophysical properties.

Atomism Revisited

The ancient atomism inspires us to reconsider everything as being composed of indivisible entities, known today as quanta of actions. The quantum of light is the familiar single quantum in its open waveform. Likewise, any other physical action is a geometric notion in terms of energy and time. The quantized systems, e.g., elementary particles take forms of geodesics, i.e., paths of least action in quest for energetic balance with surrounding quanta. The fine-structure constant, as the ratio of two actions corresponding to the electron and neutrino, allows us to deduce unambiguously the characteristic symmetries of leptons, mesons, and baryons. We exemplify the quantized structures of photon…

Novel deoxycholic acid alkylamide-phenylurea-derived organogelators

Abstract Three monomeric and three dimeric deoxycholic acid (DCA) alkylamido-phenylurea derivatives are designed based on known gelators and are synthesized and characterized by 1 H and 13 C NMR spectroscopy, ESI-TOF mass spectrometry, and elemental analyses. Among them, a monomeric derivative forms supramolecular gels in CHCl 3 and chlorobenzene, whereas a dimeric derivative gels THF and higher 1-alkanols containing 7–10 carbons. The morphologies of their xerogels are studied by scanning electron microscopy (SEM). No signature of macroscopic chirality of the gels is visible.

Molecular orbital studies on brominated diphenyl ethers. Part II—reactivity and quantitative structure–activity (property) relationships

Polybrominated diphenyl ethers (PBDEs) are widely used as flame retardants and are increasingly turning up in the environment. Their structural similarities to polychlorinated biphenyls and thyroid hormones suggest they may be a risk to human health. The present study examines the reactivity of brominated diphenyl ethers (BDEs) on the basis of the electronic structures as calculated by semiempirical AM1 self-consistent field molecular orbital (SCF-MO) method. Frontier orbital energies were used to elucidate the reactivity of BDEs in electrophilic, nucleophilic and photolytic reactions. From an examination of the frontier electron densities, the regioselectivity, or orientation, of metabolic…

N-methyl-1,2-dihydro-2-benzoylmethylenequinolines: configurational dissimilarity with unmethylated congeners

Abstract Twelve 1-methyl-1,2-dihydro-2-benzoylmethylenequinolines have been synthesized and their structures elucidated by 1 H, 13 C and 15 N NMR, UV–Vis and X-ray methods. The results unambiguously show that these compounds and the corresponding 1,2-dihydro-2-benzoylmethylenequinolines both in crystalline and in solution state are the Z and E isomers, respectively. Comparison of the X-ray structures reveal that ( Z )-1,2-dihydro-2-benzoyl-methylenequinolines are less twisted as compared to their 1-methyl derivatives. This difference is caused by formation of the quasi-aromatic six-membered ring stabilized by an intramolecular hydrogen bond in unmethylated congeners, prevented by N -methyla…

ChemInform Abstract: Concave π-Prismand Hydrocarbon [2.2.2]Cyclophanes and Their Crystalline Ag-Triflate Complexes.

New small concave hydrocarbon cyclophanes were prepared via the well-known HD-2SO2-method. The cyclophanes obtained are isomers of the very well-known [2.2.2]p,p,p-cyclophane, C24H24, a π-prismand efficiently complexing Ag+-ion. X-ray crystal structure determinations showed the bis-sulfide 7 (1,10-dithia[3.3.2]m,p,p-cyclophane) to be helically chiral and that the conformation of the parent hydrocarbon cyclophane 13 ([2.2.2]m,p,p-cyclophane) does not change dramatically upon complexation with the Ag+-ion. The 16- and 17-membered [2.2.2]m,m,p- and [2.2.2]m,p,p-cyclophane (15 and 16) also act as π-prismands and form surprisingly similar crystalline 1:1 Ag-triflate complexes (π-prismates) as th…

Multinuclear magnetic resonance study of 1,3,3-trimethylbicyclo [2.2.1]heptan-2-one (fenchone) oxime, its five monochloro derivatives and a dehydrochlorination product

Fenchone oxime, 5-exo-chlorofenchone oxime, 6-exo-chlorofenchone oxime, 7-anti-chlorofenchone oxime, 8-chlorofenchone oxime, 9-chlorofenchone oxime and a dehydrochlorination product of 10-chlorofenchone oxime were synthesized from fenchone and the corresponding chlorofenchones. The 1H, 13C and 17O NMR spectra of the oximes and the dehydrochlorination product were recorded. The NMR data were compared with the corresponding parameters obtained earlier for fenchone and monochlorofenchones in order to determine the differences between the carbonyl and oxime substituents from the NMR spectroscopic point of view, and to assign the stereochemistry of the oxime group. This stereochemistry could not…

Heteronuclear NMR Applications (Y–Cd)*

NMR spectroscopy in environmental chemistry:1H and13C NMR chemical shift assignments of chlorinated dibenzothiophenes based on two-dimensional NMR techniques andab initio MO and DFT/GIAO calculations

Methods for the Identification of Tainting Terpenoids and other Compounds from Algae

Off-flavour compounds produced by algae in freshwater ecosystems were studied for their structure using integrated sensory and spectroscopic methods: mass spectrometry (MS), nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR). Both solvent extraction and thermal desorption were used to isolate and to introduce the compounds into gas chromatography/mass spectrometry (GC/MS) and gas chromatography/Fourier transform infrared (GC/FTIR) systems. Ten ng of a terpenoid compound gave a readable IR spectrum. For 1H NMR studies the compounds were collected directly into NMR solvent by preparative gas chromatography. About 5 µg of a monoterpenoid compound was needed for a reliable 1…

1H, 13C and 15N NMR study of 2-alkylnitrosoamino-4-nitropyridines and N-oxides: An example on restricted inversion of sp3 nitrogen

Abstract The 1 H, 13 C and 15 N NMR chemical shifts of seven 2-alkylnitrosoamino-4-nitropyridines and seven 2-alkylnitrosoamino-4-nitropyridine N -oxides have been assigned. The GIAO/DFT 13 C chemical shifts of energetically optimized structures have been calculated. The results were compared to the chemical shifts of previously studied 2-alkylamino and 2-alkylnitramino derivatives of 4-nitropyridine and 4-nitropyridine N -oxide. In sterically crowded ortho -substituted congener (2-ethylnitrosoamino-3-methyl-4-nitropyridine N -oxide) restricted inversion of pyramidal amino nitrogen forms a chiral center in the molecule and makes the geminal protons of N–CH 2 -moiety diastereotopic. In 5- an…

Noncovalent Saccharide Recognition by Means of a Tetrakis(bile acid)-Porphyrin Conjugate: Selectivity, Cooperation, and Stability

Molecular recognition of Glu, Glc 2 -Glc 6 and Mal 3 by a tetrakis(bile acid)―porphyrin conjugate has been studied by using ESI-FTICR mass spectrometry. The bile acid conjugate was observed to form 1:1 noncovalent complexes with saccharides. The conjugate was found to have size-selectivity towards saccharides with three or more glucose residues. The Glc 3 and Glc 4 also formed kinetically the most stable complexes. The electron capture dissociation (ECD) experiments revealed that in complexation of an oligosaccharide three glucose residues interact with the bile acid conjugate, whereas additional glucose residues are susceptible to fragmentation. The ECD results also showed the significance…

Structure-based evaluation of the resonance interactions and effectiveness of the charge transfer in nitroamines

Structural data for five nitroamines of general formula Me2N–G–NO2 show effectiveness of the ground-state charge transfer to be most and least efficient in N,N-dimethylnitramine and in 4-N,N-dimethylamino-β-nitrostyrene, respectively. Electron-donor power of the amino nitrogen atom in the latter compound is less than that in 4-nitro-β-N,N-dimethylaminostyrene (these two compounds are isomers). Natural population analysis shows that the charge transfer from the amino to the nitro oxygen atoms is most effective in N,N-dimethylnitramine, Me2N–NO2. The nitro oxygen atoms are not the only acceptors of the negative charge lost by the amino nitrogen atom. The nitro group in two substituted nitrobe…

The influence of CH bond polarization on the self-association of 2-acylaminopyrimidines by NH/CH···O/N interactions: XRD, NMR, DFT, and AIM study

The single crystal structures of two 2-acylaminopyrimidines, where alkyl groups in acyl moiety are iso-propyl (1) and dichloromethyl (2), were solved by X-ray diffraction method. The strength of intermolecular hydrogen bonding interactions depends on the C–H bond polarization increased by exchanging two methyl groups by chlorine atoms in the adjacent substituent. The computational methods provide an additional insight into the intermolecular interactions and are utilized in explaining the differences in the observed crystal structures. The experimental and computational data together explain the differences in the formed aggregates and revealed that these simple substitutions cause crucial …

Interaction of metal ions with D-glucobenzothiazoline: isolation and characterization of the resultant products

Six different metal-ion complexes of D-glucobenzothiazoline were synthesized and characterized by analytical and spectral techniques. Formation of different types of species (ML and ML2) were observed with Cu2+, Ag+, Cd2+, Hg2+, and Zn2+ ions. Existence of an anomeric mixture in the case of the Cu2+ complex is identified from the EPR spectra, and the results were further supported by the simulated spectra. The structures were proposed based on different studies.

NMR Spectra of Anilines

1 Introduction 2 Ring and N-Substituted Anilines 3 Multinuclear NMR Studies of p-F-Aniline Derivatives 4 Dynamic NMR of Aniline Derivatives 5 Anilines with Other (Fused) Aromatic Rings 6 NMR Relaxation Studies of Aniline Derivatives 7 Solid State NMR Studies 8 Theoretical Calculations of Aniline NMR Parameters Keywords: aniline NMR spectra; aniline (aminobenzene, phenylamine); ring and N-substituted anilines; dual-substituent-parameter (DSP) analysis; cyclic amine structures; dynamic NMR of aniline derivatives; H NMR spectroscopy as measure of donor strengths; aniline derivative NMR relaxation studies

Predominance of 2-arylhydrazones of 1,3-diphenylpropane-1,2,3-trione over its proton-transfer products

2-Phenylhydrazones of 1,3-diphenyl-1,2,3-trione are the dominant tautomeric form detected in chloroform solution by 15N NMR chemical shifts. The substituent in the phenylhydrazone moiety does not affect this tautomeric preference. The substituent effect is transmitted effectively only to the hydrazone nitrogen and hydrogen atoms. Ab initio calculations show that the ketohydrazone tautomer is really very much favoured over its proton-transfer products in chloroform solution. The same tautomer was also detected in the crystal state by X-ray crystallography. Copyright © 2001 John Wiley & Sons, Ltd.

1H, 13C and 15N NMR spectral and theoretical studies of some methyl and alkylamino derivatives of 4-halopyridine N-oxides

Abstract Nine new and three earlier known 4-halogen (Cl and Br) substituted pyridine N-oxides have been prepared and their 1 H, 13 C and 15 N NMR chemical shifts assigned based on PFG 1 H, X (X= 13 C and 15 N) HMQC and HMBC experiments as well as the comparison with our earlier results for substituted pyridine N-oxide derivatives. The 15 N resonances of the pyridine nitrogen are 27–40 ppm more shielded in 4-halo-2-alkylamino-6-methyl-5-nitropyridine N-oxide than in parent 4-halopyridine N-oxide. According to quantum chemical ab initio HF/6-311G** calculations the amino tautomer of 4-chloro-2-methylamino-6-methyl-5-nitropyridine N-oxide is more stable than its imino form. Using B3LYP/6-311G*…

ChemInform Abstract: Syntheses of Some Biologically Active Compounds from Stilbenes Isolated from the Bark of Picea abies.

From the four stilbenes 1–4 isolated from the bark of Picea abies seven compounds 5–11 were obtained by hydrogenation or permethylation. 1H-, 13C-NMR and mass spectra were used for their characterization. The antileukemic activity of each compound was preliminary tested. Some compounds were further tested for their anti-HIV activity.

ChemInform Abstract: 4-Fluoroanilines: Synthesis and Decomposition.

Abstract Fourteen N- and/or 2-substituted 4-fluoroanilines were prepared (the series includes N–C2-bridged compounds). Some of them were found to be thermally unstable when dissolved in chloroform. Both 19 F NMR spectra and comparison of GIAO-DFT calculated and experimental 13 C chemical shifts were used to suggest decomposition products of 4-fluoroanilines.

1H, 13C, 15N NMR, ESI mass spectral and single crystal X-ray structural characterization of three spiro[pyrrolidine-2,3′-oxindoles]

Abstract Three spiro[pyrrolidine-2,3′-oxindoles], 1,1′,2,2′,5′,6′,7′,7′a-octahydro-2-oxo-1′-phenyl-spiro[3H-indole-3,3′-[3H]-pyrrolizine]-2′-carboxylic acid methyl ester (1), 1,1′,2,2′,5′,6′,7′,7′a-octahydro-2-oxo-1′-nitro-2′-phenyl-spiro[3H-indole-3, 3′-[3H]-pyrrolizine] (2) and 1,1′,2,2′,5′,6′,7′,7′a-octahydro-2-oxo-1′-nitro-2′-(4″-chlorophenyl)-spiro[3H-indole-3,3′-[3H]-pyrrolizine] (3) have been synthesized and their 1H, 13C and 15N spectra assigned. The chemical shift assignments are based on Pulsed Field Gradient (PFG) Double Quantum Filter (DQF) 1H, 1H correlation spectroscopy (COSY), PFG 1H, 13C Heteronuclear Multiple Quantum Coherence (HMQC) and PFG 1H,X (X = 13C and 15N) Heteronuc…

Synthesis, NMR spectral and structural studies on mixed ligand complexes of Pd(II) dithiocarbamates: First structural report on palladium(II) dithiocarbamate with SCN-ligand

Abstract Three new mixed ligand complexes of palladium(II) dithiocarbamates; [Pd(4-dpmpzdtc)(PPh3)(SCN)] (1), [Pd(4-dpmpzdtc)(PPh3)Cl] (2) and [Pd(bzbudtc)(PPh3)Cl] (3), (where, 4-dpmpzdtc = 4-(diphenylmethyl)piperazinecarbodithioato anion, bzbudtc = N-benzyl-N-butyldithiocarbamato anion and PPh3 = triphenylphosphine) have been synthesized from their respective parent dithiocarbamates by ligand exchange reactions and characterized by IR and NMR (1H, 13C and 31P) spectroscopy. IR and NMR spectral data support the isobidentate coordination of the dithiocarbamate ligands in all complexes (1–3) in solid and in solution, respectively. Single crystal diffraction analysis of complexes 1–3 evidence…

One-step synthesis of resorcarene dimers composed of two tetra-benzoxazine units

Abstract The condensation of resorcarene 1 with ethylenediamine and an excess of formaldehyde gives, under high dilution conditions, in up to 15% yield the octa-benzoxazine dimer 2 in which two molecules of 1 are connected by four bridges. The structure of 2 has been confirmed by 1 H NMR spectra and MALDI-TOF mass spectra and by hydrolysis of the oxazine rings yielding the secondary amine 3 .

N-(2-Benzoyl-4-chlorophenyl)-4-chlorobenzenesulfonamide

The title compound, C19H13Cl2NO3S, is an N-arylsulfonyl derivative of 2-amino-5-chlorobenzophenone. The compound is biologically active and shows potential to be utilized as an inhibitor of CCR2 and CCR9 receptor functions. In the crystal structure, there is an intramolecular N—H...O hydrogen bond between the amide and carbonyl groups. The benzoyl and 4-chlorophenyl groups form intramolecular and intermolecular face-to-face contacts, with a dihedral angle of 10.6 (1)° between their mean planes in both cases, and centroid–centroid separations of 4.00 (1) and 4.25 (1) Å for the intra- and intermolecular interactions, respectively.

Caffeine as a Gelator

Caffeine (a stimulant) and ethanol (a depressant) may have opposite effects in our body, but under in vitro conditions they can “gel” together. Caffeine, being one of the widely used stimulants, continued to surprise the scientific community with its unprecedented biological, medicinal and physicochemical properties. Here, we disclose the supramolecular self-assembly of anhydrous caffeine in a series of alcoholic and aromatic solvents, rendering a highly entangled microcrystalline network facilitating the encapsulation of the solvents as illustrated using direct imaging, microscopy analysis and NMR studies. Peer reviewed

Synthesis and characterization of the [Ru(η5-C5Me4CF3)(CO)2]2 and Ru6(μ3-H)(η2-μ4-CO)2(μ-CO)(CO)12(η5-C5Me4CF3) complexes

The reaction of Ru3(CO)12 with tetramethyltrifluoromethylcyclopentadiene at various ratios of the reagents was studied. Refluxing of Ru3(CO)12 with a sixfold excess of tetramethyltrifluoromethylcyclopentadiene in octane in an inert atmosphere gave a complex, which is, according to X-ray diffraction data, a dimer,trans-[Ru(η5-C5Me4CF3)(CO)2]2. The reaction under the same conditions but starting from Ru3(CO)12 and C5Me4CF3H in 2∶1 molar ratio gave a hexaruthenium cluster [Ru6(μ3-H)(η2-μ4-CO)2(μ-CO)(Co)12(η5-C5Me4CF2)], which was characterized by IR as well as1H,13C, and19F NMR spectroscopy. According to X-ray diffraction data, an Ru4 tetrahedron, in which two edges are bound by additional “br…

2,5-Dimethyl-4′-nitrobiphenyl

The title compound, C14H13NO2, is a non-planar biphenyl derivative, in which the dihedral angle between the benzene rings is 62.65 (5) °.

UV-induced solvent free synthesis of truxillic acid–bile acid conjugates

The solvent free UV-induced [2 + 2] intermolecular cycloaddition of two molecules of 3α-cinnamic acid ester of methyl lithocholate produced in 99% yield of α- and e-truxillic acid-bis(methyl lithocholate) isomers, which possess two structurally different potential binding sites. A prerequisite for this effective solid state reaction is a proper self-assembled crystal structure of the starting conjugate crystallized from acetonitrile. The crystallization of cinnamic acid ester of methyl lithocholate from acetonitrile produces two different crystalline forms (polymorphs), which is the reason for the solid state formation of two isomers of truxillic acid-bis(methyl lithocholate).

The identification of vicinally substituted cyclohexane isomers in their mixtures by 1H and 13C NMR spectroscopy.

The radical addition reactions of organobromine compounds, XBr (X = CH2COOMe, PhCH2, CHBr2 and CCl3) with cyclohexene afforded mixtures of cis/trans isomer pairs of 1-X-2-Br-cyclohexanes. In addition to benzyl benzoyloxy derivatives are formed also, when benzoyl peroxide is used as an initiator. Owing to the great difficulties in separating these cis/trans isomer pairs, they are identified directly in their mixtures by NMR spectroscopy. In addition to one-dimensional (ID) 1H, proton decoupled 13C and DEPT-135, also two-dimensional (2D) 13C-13C INADEQUATE as well as 1H-13C HMQC experiments have been used in assigning the signals of each compound in their mixtures. The identification of each …

On the carrier of inertia

A change in momentum will inevitably perturb the all-embracing vacuum, whose reaction we understand as inertia. Since the vacuum's physical properties relate to light, we propose that the vacuum embodies photons, but in pairs without net electromagnetic fields. In this physical form the free space houses energy in balance with the energy of matter in the whole Universe. Likewise, we reason that a local gravitational potential is the vacuum in a local balance with energy that is bound to a body. Since a body couples to the same vacuum universally and locally, we understand that inertial and gravitational masses are identical. By the same token, we infer that gravity and electromagnetism shar…

Multinuclear NMR study of 1,3,3-trimethylbicyclo[2.2.1]heptan-2-one (fenchone) and its six monochlorinated derivatives

1H, 13C and 17O NMR spectra of fenchone and six monochlorofenchones have been recorded. The second-order 1H NMR spectra were analysed by an iterative computer program. The 1H and 13C chlorine-induced substituent chemical shifts (SCS) were calculated. The vicinal coupling constants proved to be essential in the assignment of the chemical shifts of the geminal methyls. No clear correlation was observed between the chemical shifts of the carbonyl oxygen and the carbonyl carbon. All monochlorofenchones were previously unknown compounds and were synthesized for this work.

Novel bile acid conjugates with aryl/alkenyl linker: Synthesis and characterization

Abstract Eight potential precursors for the design of bile acid derived receptors viz. 2,6-bis[dimethyl(3α-hydroxy-5β-cholan-24-amidoethyl)ammonio-methyl]naphthalene dibromide (1), 3,3′-bis[dimethyl(3α-hydroxy-5β-cholan-24-amidoethyl)ammoniomethyl]biphenyl dibromide (2), 3,3′-bis[dimethyl(3α,7α,12α-trihydroxy-5β-cholan-24-amidoethyl)ammoniomethyl]biphenyl dibromide (3), 4,4′-bis[dimethyl(3α-hydroxy-5β-cholan-24-amidoethyl)ammoniomethyl]stilbene dibromide (4), 4,4′-bis[dimethyl(3α,7α,12α-trihydroxy-5β-cholan-24-amidoethyl)ammoniomethyl]stilbene dibromide (5), allyl-dimethyl(3α,7α,12α-trihydroxy-5β-cholan-24-amidoethyl)ammonium bromide (6), 1,4′-bis[dimethyl(3α-hydroxy-5β-cholan-24-amidoethyl…

E-2-Benzylidenebenzocycloalkanones III. Studies on transmission of substituent effects on IR carbonyl stretching frequencies and 13C NMR chemical shifts of E-2-(X-benzylidene)-1-indanones. Comparison with the IR data of E-2-(X-benzylidene)-1-indanones, -tetralones, and -benzosuberones

Abstract Single substituent parameter and dual substituent parameter analysis was applied to study transmission of substituent effects on IR carbonyl stretching frequencies of E -2-(X-benzylidene)-1-indanones ( 3 ), -tetralones ( 4 ), and -benzosuberones ( 5 ). Similar analyses were performed for selected 13 C NMR chemical shifts of some E -2-(X-benzylidene)-1-indanones ( 3 ). For a better understanding of the results semiempirical and ab initio quantum chemical calculations were performed to determine the preferred geometry and to calculate the theoretical 13 C NMR chemical shifts of the selected compounds ( 3 ). The differences among the regression coefficients were discussed in terms of …

Synthesis, Characterization, and Saccharide Binding Studies of Bile Acid − Porphyrin Conjugates

Synthesis and characterization of bile acid-porphyrin conjugates (BAPs) are reported. Binding of saccharides with BAPs in aqueous methanol was studied by monitoring changes in the visible absorption spectral of the porphyrin-moieties. Although these studies clearly showed absorbance changes, suggesting quite high if non-selective binding, the mass spectral studies do not unambiguously support these results.

Novel Porphyrin-cholic Acid Conjugates as Receptors for Biologically Important Anions

ChemInform Abstract: The Tautomerism of Nitraminopyridines

1H, 13C and 15N NMR data for nitraminopyridines are discussed in terms of tautomeric equilibria in these compounds. The favoured tautomer is determined mainly from 15N NMR spectroscopy. The chemical shift of the nitrogen atom of the nitro group in nitraminopyridines and N-nitroanilines which cannot tautomerize vary from 28·0 to 35·4 ppm in DMSO solution. 3-Nitraminopyridine and 2-nitramino-3- and -5-nitropyridines behave similarly. In the 15N NMR spectra of nitrimino-1-methyldihydropyridines, used as models, an upfield shift of that atom, different from that observed for 2-nitraminopyridine, indicates the significance of the nitrimino tautomer. In contrast, a downfield shift of the ring nit…

Novel lithocholaphanes: Syntheses, NMR, MS, and molecular modeling studies

Abstract Novel head-to-head lithocholaphanes 6 and 11 have been synthesized via precursors 1 – 5 and 7 – 10 with overall good yields, and characterized by 1 H, 13 C, and 15 N NMR spectroscopy, ESI-TOF mass spectrometry, thermal analysis, and molecular modeling. In addition, the binding abilities of 6 and 11 towards alkali metal cations have been investigated via competitive complexation studies using equimolar mixtures of Li + , Na + , K + , and Rb + -cations, and cholaphanes 6 and 11 . The formation of cation–cholaphane adducts was detected by ESI-TOF mass spectrometry. The trends in these comparative binding studies are nicely reproduced theoretically with PM3 energetically optimized stru…

Substituted Dibenzothiophenes I: Synthesis, Chromatography, Mass Spectrometry and Structure Elucidation by1H NMR Spectroscopy

Abstract Some polychlorinated and polymethylated dibenzothiophenes have been synthesized to serve as model compounds in environmental analysis. In order to obtain pure isomers, the synthesis mixtures have been fractionated with reversed-phase high performance liquid chromatography. In spite of a high sensitivity, mass spectrometry does not provide any reliable way to determine the precise structures of different isomers. Therefore, 1H NMR spectroscopy has been utilized as an aid in their analysis. The structures for two isomeric tetramethyldibenzothiophenes could be suggested on the basis of their 1H NMR spectra. Also some proposals for possible structures of two isomeric trimethyldibenzoth…

Mono-, bi- and polynuclear complexes of diphenylmethane with Cr, Co and Ru. Synthesis and investigation by 1H, 13C and 17O NMR

Abstract Complexes of diphenylmethane (Ph 2 CH 2 ): Ph 2 CH 2 Cr(CO) 3 ( 1 ), Ph 2 CH 2 [Cr(CO) 3 ] 2 ( 2 ), Ph 2 CH 2 Co 4 (CO) 9 ( 3 ), Ph 2 CH 2 [Co 4 (CO) 9 ] 2 ( 4 ), Ph 2 CH 2 Cr(CO) 3 Co 4 (CO) 9 ( 5 ) and Ph 2 CH 2 Ru 6 C(CO) 14 ( 6 ) have been prepared and characterized by 1 H and 13 C-and 17 O-NMR spectroscopy. Strong shielding effects are caused by the metal valence electrons on the 1 H- and 13 C-NMR chemical shifts of aromatic protons and carbons in π-coordinated ring(s) diphenylmethane. Generally, the order of these shielding effects on the nuclei of the aromatic rings in 1 H-NMR was Co 4 (CO) 9 6 C(CO) 14 3 and in 13 C-NMR Co 4 (CO) 9 3 6 C(CO) 14 . In addition, aromatic solve…

Configurational effects in17O NMR chemical shifts of hydroxyl-substituted, bicyclo [2.2.1]heptenes and -heptanes, their methylated derivatives and some related compounds

Well resolved natural abundance 17O NMR spectra of 27 mono-, di-, tri- and tetrahydroxybicyclo[2.2.1]heptenes and -heptanes (norbornenes or norbornanes), their methylated derivatives and some related compounds were measured for 0.5 M or saturated solutions in acetonitrile at 65°C. In addition, the 17O NMR chemical shifts of 14 aliphatic and alicyclic alcohols were also determined for reference purposes. The 17O NMR chemical shifts of all compounds were assigned. Both methyl- and hydroxyl-induced deshielding β-effects were consistent with those reported in the literature. Similarly, observed shielding γ-effects were in agreement with the earlier observations and characteristic especially for…

Diversity in Itraconazole Cocrystals with Aliphatic Dicarboxylic Acids of Varying Chain Length

The cocrystal formation potential of itraconazole, a potent antifungal drug, with C2–C10 aliphatic dicarboxylic acids has been investigated. Using two experimental screening techniques (solvent-assisted grinding and evaporation-based crystallization), the cocrystals of itraconazole with C2–C7 dicarboxylic acids have been successfully synthesized and characterized by powder X-ray diffraction, solid state nuclear magnetic resonance, Raman spectroscopy, and thermal analysis. The characterized multicomponent compounds include anhydrous cocrystals (malonic, succinic, glutaric, and pimelic acids), a cocrystal hydrate (adipic acid), and cocrystal solvates with acetone and tetrahydrofuran (oxalic a…

NMR, X-Ray and MS Investigations of Ethyl 2-Aroyl-and Ethyl 2-Arylcarbamoyl-4,5- dimethyl-1,2,3,6-tetrahydropyridazine-1- carboxylates: Flexible Multidentate Ligands

The 1H and 13C NMR spectral assignments of ethyl 2-aroyl-4,5-dimethyl-1,2,3,6-tetrahydropyridazine-1-carboxylates (1a-1h) and ethyl 2-arylcarbamoyl-4,5-dimethyl-1,2,3,6-tetrahydropyridazine-1-carboxylates (2a-2k) are given based on DQF COSY, 1H,13C HMQC and 1H,13C HMBC-measurements; the dynamics of the tetrahydropyridazine ring has been studied by 1H, 1H EXSY-technique and the structure of one congener (4′-methylphenyl-derivative, 2a) has been confirmed by X-ray structure analysis.

Reactions of Carbonyl Compounds in Basic Solutions. Part 351: The Alkaline Hydrolysis and Reactivity – Structure – Spectra Correlations of (Z)-4-(Substituted Benzylidene)-2-Phenyl-4H-Oxazol-5-Ones

The kinetics of the alkaline hydrolysis and the configuration, conformation and electronic structure were studied using IR, NMR spectroscopy, X-ray analysis and AM1 theoretical calculations for a series of (Z)-4-(substituted benzylidene)-2-phenyl-4H-oxazol-5-ones (1) and compared with analogous results reported for (E)-4-benzylidene-2-phenyl-4H-furan-5-ones (5) and related compounds.

1H,13C and17O NMR study of aromatic ring-substituted monochloro- and monobromo-(E)-3-phenylpropenals

Trans-Cinnamaldehydes (CAs) or o-, m- and p-X-(E)-3-phenylpropenals; (X = Cl or Br) were synthesized and their 1H, 13C and 17O NMR spectra were measured, assigned and analysed. The long-range benzylic couplings are discussed in terms of the conformational characteristics of the related styrene systems. The 1H, 13C and 17O NMR substituent chemical shifts of the CA derivatives were compared with those of styrene and explained by the π-electron delocalization in the conjugated CCCO bond system of CA.

A computationally feasible quantum chemical model for 13C NMR chemical shifts of PCB-derived carboxylic acids.

Two quantum chemical models have been derived for the prediction of 13C NMR chemical shifts of novel PCB acids obtained from PCBs by catalytic carbonylation. 13C isotropic shielding constants were calculated employing the GIAO (gauge-independent atomic orbital) method with density functional theory (DFT). The best results were obtained by cluster calculations, which took the solvent effects into account properly. In this approach, a solvent molecule (acetone) was attached by a hydrogen bond to every hydrogen atom present in a PCB acid, and the geometry of the molecular cluster was optimized employing the AM1 method. For 158 chemical shifts, the cross-validated standard error was 2.8 ppm and…

(1Z,3Z)-1,4-Di(pyridin-2-yl)buta-1,3-diene-2,3-diol:  The Planar Highly Conjugated Symmetrical Enediol with Multiple Intramolecular Hydrogen Bonds

1H, (13)C, and (15)N NMR spectral data show that in chloroform solution (1Z,3Z)-1,4-di(pyridin-2-yl)buta-1,3-diene-2,3-diol, OO, is in ca. 9:1 equilibrium with (3Z)-3-hydroxy-1,4-di(pyridin-2-yl)but-3-en-2-one, OK, while no 1,4-di(pyridin-2-yl)-2,3-butanedione, KK, was detected. The species present in the tautomeric mixture were identified by comparing their experimental chemical shifts with those known for similar compounds as well as with the theoretically calculated (GIAO-HF/DFT) values. Ab initio calculations show that OK and especially the highly conjugated OO forms are preferred in the tautomeric mixtures both in vacuo and in chloroform solution. Comparison of experimental (Arrhenius)…

Benson group additivity values of phosphines and phosphine oxides: Fast and accurate computational thermochemistry of organophosphorus species

Composite quantum chemical methods W1X-1 and CBS-QB3 are used to calculate the gas phase standard enthalpy of formation, entropy, and heat capacity of 38 phosphines and phosphine oxides for which reliable experimental thermochemical information is limited or simply nonexistent. For alkyl phosphines and phosphine oxides, the W1X-1, and CBS-QB3 results are mutually consistent and in excellent agreement with available G3X values and empirical data. In the case of aryl-substituted species, different computational methods show more variation, with G3X enthalpies being furthest from experimental values. The calculated thermochemical data are subsequently used to determine Benson group additivity …

2-Methyl-4-phenyl-3,4-dihydro­quinazoline

The title compound, C15H14N2, was formed during the lithiation of 2-methylquinazoline with phenyllithium followed by hydrolysis of the intermediate lithium 2-methyl-4-phenyl-4H-quinazolin-3-ide. NMR spectra as well as single-crystal X-ray structural data indicate that the reaction product to have the same structure in chloroform solution as in the crystalline state. The phenyl substituent is twisted out of the plane of the 3,4-dihydroquinazoline ring system by 86.47 (7)°. In the crystal, intermolecular N—H...N interactions connect the molecules into infinite chains.

Tautomeric preferences of phthalones and related compounds

Abstract Multinuclear magnetic resonance and IR spectra prove that although 2-(diacylmethyl)pyridines and 2-(diacylmethyl)quinolines are β-diketones, their proton transfer product present in chloroform solution is not ketoenol but enaminone (earlier opinions were contradictory). Quinoline derivatives are less zwitterionic by character than the respective pyridyl congeners. The β-diketone form itself may also be rarely present in the solution. X-ray data show that 2-(2(1H)-pyridinylidene)-1H-indene-1,3(2H)-dione, i.e., enaminone tautomer of 2-(pyridin-2-yl)-2H-indene-1,3-dione, is also the only form present in crystal. Ab initio calculations show that the enaminone is usually more stable tha…

Synthesis and characterization of lithocholic acid derived dipyrromethanes: precursors for pyrrole-steroidal macrocycles

Abstract Three steroidal dipyrromethanes, 3,3,24,24-tetrakis(pyrrol-2-yl)-5β-cholane 1 , 3,3-bis(pyrrol-2-yl)-5β-cholan-24-oic acid 2 , and methyl 3,3-bis(pyrrol-2-yl)-5β-cholan-24-oate 3 , have been prepared from 3α-hydroxy-5β-cholan-24-oic acid (lithocholic acid) 4 in good overall yields. The structures of 1 – 3 have been fully characterized by 1 H, 13 C, PFG DQF 1 H– 1 H COSY, 1 H– 1 H ROESY, 13 C DEPT-135, PFG 1 H– 13 C HMQC, PFG 1 H– 13 C HMBC, and PFG 1 H– 15 N HMBC NMR spectra. Their molecular weights and compositions have been determined by ESI-TOF and EI mass spectra, and elemental analyses. The energetically optimised geometry and isotropic 13 C NMR chemical shifts of 3,3,24,24-te…

Multinuclear magnetic resonance, electrospray ionization time-of-flight mass spectral and molecular modelling characterization of lithocholic acid amide esters with various nitrogen heterocycles

1H, 13C and 15N NMR and electrospray ionization time-of-flight mass spectrometric characterizations of five lithocholate esters of piperazine diamides are described. Two of them are cholaphane-type cyclic structures esterified with 2,2′-bipyridine-4,4 ′ - and pyridine-2,6-dicarboxylic acid and the other three esters are open structures comprising two or four lithocholyl residues. The conformational preferences of the dimeric congeners were examined by using molecular modelling and variable-temperature 1H NMR techniques. Copyright © 2003 John Wiley & Sons, Ltd.

Molecular orbital studies on brominated diphenyl ethers. Part I—conformational properties

Polybrominated diphenyl ethers (PBDEs) are widely used as additive flame retardants and quantities in the environment are on the rise. Because they are structurally related to polychlorinated biphenyls and also to thyroid hormones, there is serious concern that PBDEs may pose a danger to human health. Knowledge of their conformational properties is key to assessing their environmental fate and risk. The conformational properties of PBDEs were investigated by quantum chemical methods including semiempirical self-consistent field molecular orbital (SCF-MO), ab initio SCF-MO and density functional theory (DFT). Conformational analyses of model congeners 2,2',4,6'-tetrabromodiphenyl ether and 2…

Corrigendum to “Comparison of epimeric methyl lithocholate and methyl iso-lithocholate molecules: Single crystal X-ray structure of methyl lithocholate, ab initio HF/6-31G* optimized structures and experimental and calculated DFT/B3LYP 13C NMR chemical shifts” [J. Molstruc. 649 (2003) 207–218]

Predominance of resonance over polar effects on1H,13C and15N NMR substituent chemical shifts inN-arylglycines

Simulation of13C NMR chemical shifts for polychlorinated and polybrominated oxybenzenes with two-particle increment scheme

A two-particle system of OY-Cl and OY-Br mixed increments for predicting13C NMR chemical shifts of polyhalogenated polyoxybenzenes has been developed. It has been found that only theortho- and para-interactions of the OY and Hal substituents contribute significantly to the13C chemical shifts and that theortho-effects of the OY located between Ha1 and H and those of the OY located between two Ha1 atoms are different. Additional effects are due to solvating solvents. The increment scheme is predictive over the whole class of compounds under consideration and may be realized on personal computers.

Preparation and preliminary biological screening of cholic acid–juvenoid conjugates

Abstract Steroidal compounds have been utilized as carriers and for modification of physico-chemical properties of model biologically active secondary alcohols – juvenoids. Juvenoids are juvenile hormone analogues – environmentally safe insecticides, possessing significant biological activity towards different arthropods groups in focus on insect pest species. Structure modification of juvenoids plays important role to control the rate of liberation and decomposition of juvenoid in digestive system and can also play important role in the mode of action towards selected insect. This study presents an approach to the synthesis of steroidal monomers and dimers carrying one and two molecules of…

Encapsulation of Et3N+–H···OH2 in a hydrogen-bonded resorcarene capsule

In the crystalline state a resorcarene dimer linked by ten hydrogen-bonding water molecules encapsulates the hydrogen-bonded complex Et3N+–H···OH2 while bromide anions are positioned outside the cavity.

Gas chromatographic study of acetyl derivatives of chlorinated 4-hydroxybenzaldehydes

The GC retention times of 4-hydroxybenzaldehyde and its chloro derivatives have been measured on three nonpolar capillary columns. Multiple linear regression analysis has been used to explain the mobility of chlorinated compounds relative to the reference compound 4-hydroxybenzaldehyde. The most important effects have shown to be due to the number of chlorine atoms and the substituents ortho to the formyl group. Other effects have also been observed but found to be unable to explain the GC data.

Ultrasound accelerated esterification of bile acids

In this study power ultrasound accelerated esterification reactions of some model substances and bile acids were done. In the model reactions the best result was 19-fold increase in the reaction rate when using ultrasound and the temperature was allowed to rise during the irradiation. In the case of bile acid methyl esters a clear increase in the reaction rates was also observed by ultrasonic irradiations.

NMR Spectroscopy, Heteronuclei, Y-Cd

NMR spectral assignment of substituted salicylaldoximes by inverse pulse techniques withz-gradient selection: correlation of NMR parameters with substituent constants

Synthesis, Characterization, Thermal and Antimicrobial studies of N-substituted Sulfanilamide derivatives

Abstract Four sulfanilamide derivatives N -[4-(phenylsulfamoyl)phenyl]acetamide (1), 4-amino- N -phenylbenzenesulfonamide (2), N -[4-(phenylsulfamoyl)phenyl]benzamide (3) and N -{4-[(3-chlorophenyl)sulfamoyl]phenylbenzamide (4) were synthesized and characterized by Infra-Red (IR), Nuclear Magnetic Resonance (NMR) and UV–visible (UV–Vis) spectra. Also Liquid Chromatographic (LCMS) and High Resolution Mass Spectrometric (HRMS) methods were used. Crystal structures of 1–4 were determined by single crystal X-ray diffraction (XRD) and their conformational and hydrogen bond (HB) network properties were examined with survey of the literature data. Compounds 1 and 2 crystallize in the same orthorho…

13C NMR study on the methoxy carbon chemical shifts in chloro-substituted anisoles and guaiacols

The 13C NMR chemical shifts of methoxy carbons in chlorinated anisoles and guaiacols have been measured for acetone-d6 solutions. Multiple linear regression analysis, and also ‘simple sum rule’ calculations, have been used to estimate the effects of the chlorine atoms (the position and degree of substitution) on the chemical shifts. The most important effects have shown to be due to the chlorine atoms adjacent to the methoxy and hydroxy substituents. For chlorinated guaiacols, the greatest effect is due to the chlorine atom adjacent to the methoxy group. For chlorinated anisoles, the substituents adjacent to the methoxy group (2,6-disubstitution) cause large effects. For both groups of comp…

Spectral and microscopic study of self-assembly of novel cationic spermine amides of betulinic acid

Supramolecular characteristics of two spermine amides of betulinic acid (1 and 2) were studied by measuring and evaluating their UV-VIS-NIR spectra in aqueous acetonitrile and DOSY-NMR spectra in tetradeuteromethanol, accompanied by atomic force microscopy (AFM) images, scanning electron microscopy (SEM) micrographs, and transmission electron microscopy (TEM) micrographs. Fibrous supramolecular self-assembly of 1 and 2 was observed by AFM images, as well as by the SEM and TEM micrographs. Bathochromic shifts of the absorbance maximum at 870nm to 1015-970nm in the UV-VIS-NIR spectra were observed with increasing water content in the acetonitrile/water systems, indicating formation of fibrous…

Unraveling the packing pattern leading to gelation using SS NMR and X-ray diffraction: direct observation of the evolution of self-assembled fibers

A detailed understanding of the mode of packing patterns that leads to the gelation of low molecular mass gelators derived from bile acid esters was carried out using solid state NMR along with complementary techniques such as powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and polarizing optical microscopy (POM). Solid state 13C{1H} cross polarization (CP) magic angle spinning (MAS) NMR of the low molecular mass gel in its native state was recorded for the first time. A close resemblance in the packing patterns of the gel, xerogel and bulk solid states was revealed upon comparing their 13C{1H}CPMAS NMR spectral pattern. A doublet r…

Microwave assisted synthesis and solid-state characterization of lithocholyl amides of isomeric aminopyridines

Microwave (MW) assisted synthesis and solid state structural characterizations of novel lithocholyl amides of 2-, 3-, and 4-aminopyridine are reported. It is shown that the MW technique is a proper method in the preparation of N-lithocholyl amides of isomeric aminopyridines. It offers many advantages compared to conventional heating. The molecular and crystal structures as well as the polymorphic and hydrated forms of prepared conjugates with their thermodynamic stabilities have been characterized by means of high resolution liquid- and solid-state NMR spectroscopy, single crystal and powder X-ray diffraction, and thermogravimetric analysis. Owing to the many biological functions of bile ac…

Association of N-(Pyridin-2-yl),N′-substituted Ureas with 2-Amino-1,8-naphthyridines and Benzoates: NMR and Quantum Chemical Studies of the Substituent Effect on Complexation

Association of four N-(pyridin-2-yl),N'-R(1)-ureas (R(1) = ethyl, n-butyl, phenyl, and tert-butyl) with substituted 2-amino-1,8-naphthyridines and benzoates were studied by (1)H NMR spectroscopic titrations and quantum chemical calculations. The benzoates and 2-amino-1,8-naphthyridines were selected as representatives of double and triple hydrogen bonding counterparts, respectively. The classical substituent effect on the association was studied. A prerequisite and a crucial step for the complex formation was the breaking of the intramolecular hydrogen bond in urea derivatives. The QTAIM calculation method was employed to explain the hydrogen bonding within complexes. In the case of benzoat…

Novel Porphyrin-Cholic Acid Conjugates as Receptors for Biologically Important Anions

A series of novel receptors showing high binding affinity in aqueous media for biologically important anions are reported. These naturally chromophoric porphyrin-based receptors contain cholic acids connected via quaternary alkyl ammonium amido linkages.

Sterically and guest-controlled self-assembly of calix[4]arene derivatives.

In solvents such as chloroform or benzene, tetraurea calix[4]arenes 1 form dimeric capsules in which one solvent molecule is usually included as guest. To explore the structural requirements for the formation of such hydrogen-bonded dimers we replaced one p-tolylurea residue by a simple acetamide function. The resulting calix[4]arene 2 a, substituted at its wide rim with one acetamide and three p-tolylurea functions, assumes a C(1)-symmetrical conformation in apolar solvents as shown by (1)H NMR, which is not compatible with the usual capsule. In the crystalline state, four molecules of 2 a, adopting a pinched cone conformation, assemble into a quasi S(4)-symmetrical tetramer stabilized by …

13C and17O NMR study of methoxy groups in chlorinated Di- and trimethoxybenzenes

13C and 17O NMR data [chemical shifts and 1J(CH) values] for the methoxy groups in isomeric 1,2-, 1,3- and 1,4-dimethoxybenzenes, 1,2,3-trimethoxybenzenes and most of their chlorinated derivatives and some related brominated compounds were measured for CDCl3 solutions. The 17O NMR chemical shifts show up to 60 ppm dispersion. Comparison between the compounds with and without adjacent chlorine atoms (2,6-di- and 2,4,6-tri-substitution) also showed a clear methoxy carbon chemical shift change. The number and position of the chlorine atoms in the aromatic ring give small but observable effects on the 17O NMR chemical shifts of the methoxy group if it is coplanar with the aromatic plane. Simila…

Solvent effects of pyridine on the NMR spectra of carboxylic acids. I—study of the acrylic,trans-crotonic and 3-butenoic acids

Proton magnetic resonance spectral parameters of acrylic, trans-crotonic and 3-butenoic acids, their methyl esters and the corresponding alcohols (COOH substituted by CH2OH) have been measured for 5% (w/v) solutions in carbon tetrachloride and in pyridine-d5 at 33·5 °C. The total solvent effect of pyridine on the shifts of the skeleton protons of the acid was found to consist of three different effects independently measured from the reference samples.

1H and13C NMR spectroscopy of brominated diphenyl ethers. A multiple linear regression analysis

The 1H and 13C NMR chemical shifts and 1H, 1H coupling constants of 27 brominated diphenyl ethers are reported. The increment models for the bromine substituent effects on the 1H and 13C NMR chemical shifts were constructed based on a multiple linear regression analysis. In addition to the single substituent effects, two particle increments and corrective terms for conformational effects are included in these models in order to obtain a reliable prediction of chemical shifts. Copyright © 2000 John Wiley & Sons, Ltd.

Synthesis, characterization and the first crystal structure of the Zn(II) complex of 4,6-O-ethylidine-N-(2-hydroxybenzylidene)-β-D-glucopyranosylamine

4,6-O-Ethylidine-N-(2-hydroxybenzylidene)-β-D-glucopyranosylamine (H3L1) and N-(5-bromo-2-hydroxybenzylidene-4,6-O-ethylidine-β-D-glucopyranosylamine (H3L2) molecules possessing a–C-1–N=C(H)–moiety for metal-ion binding were synthesized by condensing the 4,6–O–ethylidene–β–D–glucopyranosylamine with salicylaldehyde or 5–bromosalicylaldehyde. Complexes of these ligands with Zn(II) were isolated and characterized using elemental analysis, FTIR, UV–Vis absorption, NMR spectroscopic and FAB mass spectrometric techniques. The structure of the Zn(II) complex derived from H3L1 was established for the first time by a single-crystal X-ray diffraction study. The anomeric nature of the saccharide moie…

N,N-Di-n-octyl-N,N-dimethyl and N,N-di-n-nonyl-N,N-dimethyl ammonium cholates: 13C and 15N CPMAS NMR, powder X-ray diffraction and thermoanalytical characterization

Abstract N,N-Di-n-octyl-N,N-dimethyl cholate (1) and N,N-di-n-nonyl-N,N-dimethyl ammonium cholate (2) have been prepared by crystallization from equimolar mixtures of sodium cholate and quaternary N,N-di-n-alkyl-N,N-dimethyl (n-octyl or n-nonyl) ammonium bromides. The formed crystalline materials have been structurally characterized by 13C and 15N cross polarization magic angle spinning (CPMAS) NMR, powder X-ray diffraction (PXRD) and thermoanalytical (TGA/DTA and DSC) methods and compared with each other. Powder X-ray diffraction patterns of 1 and 2 reveal clear similarities. Combined with the thermoanalytical data of these structures an existence of two hydrated polymorphs (most probably …

Effect of π-Electron Delocalization on Tautomeric Equilibria – Benzoannulated 2-Phenacylpyridines

Most benzoannulated 2-methylpyridines react with phenyllithium and substituted alkyl benzoates to give the corresponding 2-phenacylpyridines. 3-Methylisoquinoline is transformed into 2-benzoyl-3-methyl-1-phenyl-1,2-dihydroisoquinoline under these conditions, but replacement of phenyllithium with lithium isopropylcyclohexylamide is effective for production of 3-phenacylisoquinolines. Except in the cases of some substituted 6-phenacylphenanthridines, tautomeric mixtures of benzoannulated 2-phenacylpyridines in chloroform solution always contain the ketimine forms.(Z)-2-(2-Hydroxy-2-phenylvinyl)pyridine (enolimine) forms also contribute if the pyridine ring is not benzoannulated or if such ann…

ChemInform Abstract: Intramolecular Cyclization of Chloral Allyl Hemiacetal under the Action of the Fe(CO)5-DMF System.

Chloral allyl hemiacetal undergoes cyclization in the presence of the Fe(CO)5-DMF system to form 3,3,5-trichloro-2-hydroxytetrahydropyran rather than a butyrolactone derivative.

13C and15N NMR chemical shift assignments ofN-1-(2- azidoethyl)-4-R-pyrimidin-2-ones by1H,X HMQ(B)C withz-gradient selection

13C and 15N NMR chemical shift assignments based on z-gradient selected 1H,X (X=13C and 15N) HMQC and HMBC experiments are reported for N-1-(2-azidoethyl)pyrimidin-2-one (ring system of cytosine), its five 4-R derivatives [where R=NH2, OCH3, N(CH2)4, NHCH2CH(CH3)2 and N(CH3)2] and 2-azidoethyl tosylate. The possibilities of detecting all nitrogens in these molecules containing (i) an azido group at N-1 and (ii) an electronegative substituent at C-4 are limited. First, the terminal nitrogen of the azido group is difficult to observe because the nearest proton (in a CH2 group) is located four bonds away from it. Second, in contrast to N-1, N-3 in N-1-(2-azido-ethyl)-4-pyrimidin-2-ones remaine…

Bile acid amidoalcohols: simple organogelators.

Simple bile acid amide synthesis of lithocholic and deoxycholic acids with 2-aminoethanol and 3-aminopropanol are reported. The structural properties of these amides were examined by NMR spectroscopic, ESI-TOF mass spectral, and X-ray crystallographic methods. The gelation properties of these amides in common organic solvents and in three different water solutions were also investigated using Tyndall effect, SEM, TEM, and optical microscopy. 2-Hydroxyethylamides were found to be effective gelators in chlorinated organic solvents and 3-hydroxypropylamides in aromatic solvents. Both derivatives thicken neutral and acidic water solutions.

Horseradish peroxidase-catalyzed oxidation of chlorophyll a with hydrogen peroxide Characterization of the products and mechanism of the reaction

AbstractHorseradish peroxidase was verified to catalyze, without any phenol, the hydrogen peroxide oxidation of chlorophyll a (Chl a), solubilized with Triton X-100. The 132(S) and 132(R) diastereomers of 132-hydroxyChl a were characterized as major oxidation products (ca. 60%) by TLC on sucrose, UV–vis, 1H, and 13C NMR spectra, as well as fast-atom bombardment MS. A minor amount of the 152-methyl, 173-phytyl ester of Mg-unstable chlorin was identified on the basis of its UV–vis spectrum and reactivity with diazomethane, which converted it to the 131,152-dimethyl, 173-phytyl ester of Mg-purpurin 7. The side products (ca. 10%) were suggested to include the 173-phytyl ester of Mg-purpurin 18,…

Hydrogen-Bonded Analogues of Cavitands

Novel Applications of Dynamic NMR in Organic Chemistry

Abstract This review article is oriented on NMR applications in studying various dynamic processes of organic molecules. The topic as a whole is too large to be covered exhaustively in one article or by one author. Therefore, the literature searches are limited mainly for the years 1999–2001. Further, many interesting branches joined essentially with organic chemistry such as supramolecular and organometallic chemistry are left outside this article because there exist recent reviews on these topics. Similarly, the theoretical background of dynamic NMR is not included. The nature of dynamic NMR itself is changing with the recent progress in computational possibilities to estimate the differe…

2-Acylamino- and 2,4-bis(acylamino)pyrimidines as supramolecular synthons analysed by multiple non-covalent interactions. DFT, X-ray diffraction, and NMR spectral studies

Intermolecular interactions of ten 2-acylamino and 2,4-bis(acylamino)pyrimidines (7 of which are previously unknown) have been investigated by X-ray structural, quantum chemical (DFT), and NMR spectral methods. Especially the concentration dependencies of the (1)H NMR chemical shifts and titrations with other molecules capable of multiple hydrogen bonding provided useful information regarding their association via triple or quadruple hydrogen bonding, which is controlled by the conformational preferences of 2-acylamino- and 2,4-bis(acylamino)pyrimidines. On comparison of the properties of 2-acylamino- and 2,4-bis(acylamino)pyrimidines with the corresponding pyridines, an additional nitrogen…

Systematic study of physicochemical properties of a homologous series of aminobisphosphonates

Aminobisphosphonates, e.g., alendronate and neridronate, are a well known class of molecules used as drugs for various bone diseases. Although these molecules have been available for decades, a detailed understanding of their most important physicochemical properties under comparable conditions is lacking. In this study, ten aminobisphosphonates, H2N(CH2)nC(OH)[P(O)(OH)2]2, in which n = 2–5, 7–11 and 15 have been synthesized. Their aqueous solubility as a function of temperature and pH, pKa-values, thermal stability, IR absorptions, and NMR spectral data for bothliquid (1H, 13C, 31P-NMR) and solid state (13C, 15N and 31P-CPMAS NMR) were determined. peerReviewed

Chemometrics:  An Important Tool for the Modern Chemist, an Example from Wood-Processing Chemistry

This study briefly outlines the idea of principal component analysis and cross-correlation calculations (applied chemometrics) and presents an illustrative example from wood-processing chemistry. The applicability of chemometric data analysis was demonstrated by investigating the various structural changes that take place in dissolved and degraded lignin ("kraft lignin") during laboratory-scale kraft pulping of Scots pine (Pinus sylvestris) and silver birch (Betula pendula). The structural data (31P NMR and size exclusion chromatographic data) on kraft lignin were further processed by chemometric multivariate techniques (PCA and 2DCC), confirming, for example, that the cleavage of beta-aryl…

In situ formation of steroidal supramolecular gels designed for drug release

In this work, a steroidal gelator containing an imine bond was synthesized, and its gelation behavior as well as a sensitivity of its gels towards acids was investigated. It was shown that the gels were acid-responsive, and that the gelator molecules could be prepared either by a conventional synthesis or directly in situ during the gel forming process. The gels prepared by both methods were studied and it was found that they had very similar macroand microscopic properties. Furthermore, the possibility to use the gels as carriers for aromatic drugs such as 5-chloro-8-hydroxyquinoline, pyrazinecarboxamide, and antipyrine was investigated and the prepared two-component gels were studied with…

trans-4-tert-Butyl-1-methylcyclohexanol hemihydrate

The title compound, C11H22O·0.5H2O, is a hemihydrate of trans-4-tert-butyl-1-methyl­cyclo­hexa­nol, containing one water and two organic mol­ecules in the asymmetric unit. Crystals were obtained from an NMR sample by very slow evaporation of the solvent. In the solid state, the title compound forms a double-layered structure with the organic and water mol­ecules connected by O—H⋯O hydrogen bonds.

Solid state NMR studies of gels derived from low molecular mass gelators

The emergence of NMR crystallography provides a unique opportunity to study solids, gels and xerogels, thereby providing ample information to elucidate molecular packing in the native gel. This review details the importance as well as the application of solid state NMR spectroscopy combined with other analytical tools to study gels derived from low molecular mass organo- and hydrogelators.

Synthesis, structure and reactivity of trans-UO22+ complexes of OH-containing ligands †

trans-Dioxouranium dinuclear complexes of a few OH-containing ligands possessing N-, O-binding sites were synthesized and characterised. Seven of these were also structurally characterised by single crystal X-ray diffraction. All these complexes exhibit symmetric U2O2 core structures in addition to having a seven-co-ordinated environment about each uranium centre. Even when the ligand possessed more than one CH2OH group, only one such group was found to be involved both in chelation as well as in bridging. These complexes exhibited facile transmetallation reactions with vanadium and molybdenum precursors. Though their core structures are alike, the complexes differ in their lattice arrangem…

Unequivocal determination of isomeric products of reaction between 3-methyl-1-phenyl-2-pyrazoline-4,5-dione and aromatic 1,2-diamines

Abstract Regioselectivity of condensation of 3-methyl-1-phenyl-2-pyrazoline-4,5-dione with aromatic 1,2-diamines is dependent on substituent present. Isomeric 3-methyl-1-phenyl-1H-pyrazolo-[3,4-b]-quinoxaline products are distinguished by comparison of their 2D z-gradient selected 1H, 15N HMBC (Heteronuclear Multiple Bond Correlation) spectra. Multiplicity of H5 signal, which is recognizable by the cross-peak for CH3(3)-N4 and H5-N4 interactions, indicates substitution in position 6 or 7. The applied method is expected to be useful for structure determinations in other positional isomers.

Nitramino, NRNO2 (R = H, CH3), as a substituent.13C and15N NMR spectroscopic study of nitraminobenzenes and -pyridines

In order to clarify the special properties of the aryl-bound nitramino substituent NRNO 2 (R=H, CH 3 ), 13 C and 15 N NMR spectra of six nitraminobenzenes and nine nitraminopyridines were measured in DMSO-d 6 and their chemical shifts assigned. 1 H NMr chemical shifts and spin-spin coupling constants of all the compounds were also determined. In contrast to the behaviour of nitropyridines or -benzenes studied previously, most of the present compounds gave very broad 17 O NMR lines even at elevated temperatures and their 17 O NMR data were not useful for any reliable conclusions

3α-Hydroxy-N-(3-hydroxypropyl)-5β-cholan-24-amide

The title compound, C27H47NO3, is a (3-hydroxypropyl)amide derivative of naturally occurring enantiopure lithocholic acid (3-hydroxy-5-cholan-24-oic acid). The molecule contains four fused rings: three six-membered rings in chair conformations and one five-membered ring in a half-chair form. The two terminal six-membered rings are cis-fused, while other rings are trans-fused. The structure contains an intramolecular O—H O hydrogen bond and a similar hydrogen-bond framework to the corresponding deoxycholic and chenodeoxycholic acid derivatives. Intermolecular O— H O and N—H O interactions are also present in the crystal. This compound seems to have at least two polymorphic forms from a compa…

Transition metal–saccharide chemistry: synthesis, characterization and solution stability studies of cis-dioxomolybdenum saccharide complexes

Six cis-dioxomolybdenum(VI) complexes of simple monosaccharides (D-glucose, D-fructose, D-galactose, D-mannose, D-ribose and D-xylose) have been synthesized and characterized by a variety of analytical and spectral methods. Both the solution and solid-state studies have supported the presence of dimeric structures, formed through the cis-MoO2 moieties and the bridging saccharide units. Solution stability of these complexes as a function of time has also been addressed.

High-resolution gas chromatographic-mass spectrometric determination of neutral chlorinated aromatic sulphur compounds in stack gas samples

Abstract Four stack gas samples from waste incineration were analysed by high-resolution GC-MS for neutral chlorinated aromatic sulphur compounds such as polychlorinated dibenzothiophenes, thianthrenes and diphenyl sulphides. Samples were analysed tentatively also for some methylated derivatives of these compounds. The stack gas samples had earlier been found to contain some tri- and tetrachlorodiphenyl sulphides. Two of the stack gas samples contained tetra- and pentachlorodibenzothiophenes. One sample was strongly suspected to contain some tri- and tetrachlorothianthrenes in low concentrations. No methylated derivatives of these compounds could be found. Polychlorothianthrenes, some polyc…

Substituted methyl 5β-cholan-24-oates II.13C NMR spectral assignment

The 13C NMR spectra were recorded and assigned for nine derivatives of methyl 5β-cholan-24-oates (esters of bile acids) including hydroxy, oxo and/or acetyloxy groups. Assignments were based on the empirical substituent-induced chemical shifts (SCS), spectral comparison with compounds of similar structure, distortionless enhancement by polarization transfer (DEPT) and proton coupled 13C NMR measurements.

Structural, Thermoanalytical and Molecular Modeling Studies on N-(3-hydroxypropyl) 3a,12a-Dihydroxy-5b-cholan-24-amide and Its Monohydrates

The synthetic method for preparing N-(3-hydroxypropyl) 3 alpha,12 alpha-dihydroxy-5 beta-cholan-24-amide can lead to formation of at least three different crystal forms - an anhydrous compound and two monohydrates. The structural and thermal properties of these forms have been characterized by 13C-CP/MAS-NMR and IR spectroscopy, thermo- gravimetry, differential scanning calorimetry and by powder and single crystal x-ray crystallography. In addition, theoretical 13C-NMR chemical shift calculations were also performed for the anhydrous compound and for the first monohydrate, starting from single crystal structures and the structures of these species have now been verified. The first monohydra…

Glycosylamines of 4,6-O-butylidene-α-d-glucopyranose: synthesis and characterization of glycosylamines, and the crystal structure of 4,6-O-butylidene-N-(o-chlorophenyl)-β-d-glucopyranosylamine

A total of nine glycosylamines of 4,6-O-butylidene-α-D-glucopyranose were synthesized using primary amines having various groups in their ortho- or para-positions. Among these, six are monoglycosylamines, including one primary glycosylamine, and three are bis-glycosylamines. All these compounds were characterized by 1H, 1H–1H COSY, 1H–13C COSY and 13C NMR spectroscopy and FTIR spectra. The FAB mass spectra provided the molecular weights of the products by exhibiting the corresponding molecular ion peaks. The crystal structure of 4,6-O-butylidene-N-(o-chlorophenyl)-β-D-glucopyranosylamine revealed the C-1 glycosylation, the β-anomeric nature, and the 4C1 chair conformation of the saccharide …

Multinuclear 1H, 13C and 15N NMR study of some substituted 2-amino-4-nitropyridines and their N-oxides.

1H, 13C and 15N NMR chemical shift assignments based on pulsed field gradient selected PFG 1H,X (X = 15C and 15N) HMQC and HMBC experiments are reported for three 4-nitropyridine N-oxides and four 4-nitropyridines. It was found that an ortho effect of a methyl group inhibits the deshielding effect of the 4-nitro group and that this effect and the so-called back donation is influenced by electronegativity and position of substituents in the multisubstituted pyridine N-oxides. The shielding effect of N-oxide group is most pronounced in the 15N NMR chemical shifts of the studied compounds. This effect is further modified by methylamino, methylnitramino, 5- or 3-methyl and 4-nitro groups. Among…

C–S bond cleavage by cobalt: synthesis, characterization and crystal structure determination of 1,2-di-(o-salicylaldiminophenylthio)ethane and its Co(III) product with C–S bond cleaved fragments

1,2-Di-(o-salicylaldiminophenylthio)ethane reacts with Co(II) salts to form a complex with oxidative cleavage of the C–S bond, to result in the formation of a Co(III) complex of the cleaved ligands.

Cyclopentadienyl derivatives of octahedral carbonylcarbide hexaruthenium clusters: synthesis, NMR, IR and X-ray characterization

Abstract The reaction of hexanuclear carbonylcarbide cluster Ru6C(CO)17 (1) with pentamethylcyclopentadiene by reflux in heptane leads to a new chelate cluster Ru6C(μ-η1-η5-CH2C5Me4)(CO)14 (2). The compound 2 contains a CH2 group α-bonded to one of the Ru atoms in the Ru6 cluster and a C5Me4-ligand η5-coordinated by the adjacent Ru atom of the Ru6 cluster. Reflux of 1 in hexane with two molecular equivalents of nickelocene, Ni(C5H5)2  NiCp2, used as a source of cyclopentadiene yields the Ru6C(CO)12Cp2 (3) cluster. The compounds 2 and 3 have been characterized by NMR and IR spectroscopy and their crystal structures determined by X-ray diffraction studies.

Polymorphism and versatile solvate formation of thiophanate-methyl

The polymorphism of a fungicide, thiophanate-methyl (TM), was investigated with conventional solvent screening methods. Two polymorphs, the thermodynamically most stable form I and the less stable form II, were found. TM was also found to crystallize as a plethora of different solvates which produced mostly form II upon desolvation. The structures of form I and form II and the fourteen discovered solvates were solved by single crystal X-ray diffraction. The most stable forms were further characterized by powder diffraction, thermoanalytical (TG/DTA, DSC and thermomicroscopy) and spectroscopic (IR, Raman, ¹³C CP/MAS NMR) methods. peerReviewed

Lanthanide–saccharide chemistry: synthesis and characterisation of Ce(III)–saccharide complexes

A series of nine Ce(III) complexes has been synthesised with seven different monosaccharides (D-glucose, D-fructose, D-galactose, D-mannose, L-sorbose, D-ribose and D-xylose) and two different disaccharides (D-maltose and L-lactose), and these have been characterised with various analytical, spectral, magnetic and electrochemical techniques. The NMR studies have highlighted some interesting features about the metal-ion-binding pattern of the saccharides. Some additional coordination has been proposed along with the chelating groups in the saccharide molecules, based on the shifts in 13C NMR spectra. On the other hand, solution absorption studies and solid-state magnetic susceptibilities hav…

Synthesis and characterization of novel bile-acid – heteroaryl conjugates with N-(2-aminoethyl)amido linker

Abstract Four novel bile acid conjugates N-[2-([2,2′]-bithiophen-5-ylmethyl)aminoethyl]-3α-hydroxy-5β-cholan-24-amide (1), N-[2-([2,2′]-bithiophen-5-ylmethyl)aminoethyl]-3α,7α,12α-trihydroxy-5β-cholan-24-amide (2), N-[2-(1H-pyrrol-2-ylmethyl)aminoethyl]-3α-hydroxy-5β-cholan-24-amide (3), N-[2-(pyridin-2-ylmethyl)aminoethyl]-3α-hydroxy-5β-cholan-24-amide (4) have been synthesized in moderate to good yields, and their structures have been characterized by 1H, 13C, 13C DEPT-135, PFG 1H,13C HMQC, and PFG 1H,13C HMBC NMR spectra. Their molecular weights and elemental compositions have been determined by ESI-TOF mass spectrometry and elemental analyses. Crystal structure of 1 characterized with o…

Synthesis and characterization of Sn(IV) complexes of lower rim 1,3-diacid derivative of calix[4]arene and their protective effects on tissue oxidative stress and essential metal concentration in lead exposed male Wistar rats

The two Sn(IV) complexes synthesized using calix[4]arene-1,3-di-acid derivative were characterized by analytical, 1H, 13C and 119Sn NMR, matrix assisted laser desorption ionization mass, and 119Sn Mossbauer techniques and found that the complexes are tetranuclear possessing structurally two different types of tin centers. These complexes were evaluated for their protective value against blood and tissue oxidative stress in lead exposed male albino rats of Wistar strain. The results suggest that the two tin complexes significantly protect changes in lead induced biochemical variables indicative of heme synthesis pathway and exhibit only moderate effect on tissue oxidative stress. The benefic…

Self-Organization of 2-Acylaminopyridines in the Solid State and in Solution

Aggregation of 2-acylaminopyridines and their 6-methyl derivatives in chloroform solution was studied by (1)H, (13)C, and (15)N NMR spectroscopies. The results were compared with (13)C and (15)N CPMAS NMR and IR spectral as well as with X-ray structural data. Intermolecular interactions in solution and in solid state were found to have a similar nature. Relatively strong N(amide)-H···N(pyridine) intermolecular hydrogen bonds enable dimerization to take place. Steric interactions in N-pivaloyl- and N-1-adamantylcarbonyl as well as that caused by the 6-methyl group hinder formation of the dimeric aggregates stabilized by the N(amide)-H···N(pyridine) intermolecular hydrogen bonds. In general, …

17O NMR chemical shifts of 3-(substituted methylene)-(Z)-1(3H)-isobenzofuranones: correlations with IR stretching wavenumbers and AM1 charges

Influence of Bond Fixation in Benzo-Annulated N-Salicylideneanilines and Their ortho-C(O)X Derivatives (X = CH3, NH2, OCH3) on Tautomeric Equilibria in Solution

1H, 13C, and 15N NMR spectra show that an ortho-C(=O)X group present in the molecules of N-salicylideneanthranilamide (X = NH2), methyl N-salicylideneanthranilate (X = OCH3), N-salicylidene-o-aminoacetophenone (X = CH3), and their benzo analogues have only a minor effect on the tautomeric OH/NH-equilibrium in solution. Only two of three possible tautomers were detected. Lability of the absent form was proved by theoretical calculations. Calculated energies show that the enolimino form (OH) is less stable than the enaminone (NH) form only for dibenzo-annulated N-salicylideneanilines. The population of each species in the tautomeric mixture was found to be inversely proportional to its energy…

N-{4-[(3-Methylphenyl)sulfamoyl]phenyl}benzamide

In the title compound, C20H18N2O3S, the dihedral angle between the central benzene ring and the amide group is 24.1 (3) and that between this ring and the aromatic ring of the tolyl group is 68.2 (16). In the crystal, adjacent molecules are linked by N—HO hydrogen bonds into a linear chain running along [100]. Weak C—HO contacts also occur. Extensive weak – interactions exist from both face-to-face and face-to-edge interactions occur between the aromatic rings [centroid–centroid distances = 3.612 (2) and 4.843 (2) A˚ ]. Related peerReviewed

Systematic study of the physicochemical properties of a homologous series of aminobisphosphonates

ABSTRACT: Aminobisphosphonates, e.g., alendronate and neridronate, are a well known class of molecules used as drugs for various bone diseases. Although these molecules have been available for decades, a detailed understanding of their most important physicochemical properties under comparable conditions is lacking. In this study, ten aminobisphosphonates, H2N(CH2)nC(OH)[P(O)(OH)2]2, in which n = 2-5, 7-11 and 15 have been synthesized. Their aqueous solubility as a function of temperature and pH, pKa-values, thermal stability, IR absorptions, and NMR spectral data for both liquid (1H, 13C, 31P-NMR) and solid state (13C, 15N and 31P-CPMAS NMR) were determined. Peer reviewed

Structural characterization of β-2′-pyridylaminocrotonoyl-2-pyridylamide by ESI-MS, NMR, single crystal X-ray analysis and ab initio methods

Abstract In contradiction with earlier reports 1H, 13C and 15N NMR spectra show that β-2′-pyridylaminocrotonoyl-2-pyridylamide is the only form present in chloroform solution. According to the X-ray data the same tautomer exists also in the crystal state. The studied amide has a dimeric form where the monomer molecules are held together by two intermolecular hydrogen bonds. The NMR spectral data show that there is also an intramolecular hydrogen bond in each monomer subunit. The dilution experiments and variable-temperature 1H NMR runs show that β-2′-pyridylaminocrotonoyl-2-pyridylamide tends to form the dimers also in chloroform solution at higher concentrations. The ESI-TOF MS measurement…

Possibilities of multinuclear NMR in the chemistry of heteroorganic compounds

2-exo,5-endo,8,8,10-Pentachlorobornane

The title compound, C(10)H(13)Cl(5), is a polychlorinated monoterpene and a Toxaphene congener. This compound is also the only penta-chlorinated derivative of camphene formed via ionic chlorination. Previously, the title compound was thought to be 2-exo,5-endo,9,9,10-penta-chloro-bornane, but X-ray structural analysis showed it to have a different structure and rather to be 2-exo,5-endo,8,8,10-penta-chloro-bornane. The title compound shows static disorder and almost half the molecule was divided in two partitions with an occupancy ratio of 0.575 (major) to 0.425 (minor). The repulsive close contacts of Cl atoms could possibly be the cause for this disorder.

1H,13C and17O NMR spectroscopic study of four bicyclo [3.1.1]heptenes (derivatives of α-pinene) and four bicyclo[3.1.1]heptanes (derivatives of β-pinene)

Four derivatives of 2, 6, 6-trimethylbicyclo[3.1.1]hept-2-ene (α-pinene) and four derivatives of 2-methylene-6, 6-dimethylbicyclo[3.1.1]heptane (β-pinene) were synthesized and their 1H, 13C and 17O NMR spectra were measured, analysed and assigned. The 1H NMR spectral parameters were obtained by computer-aided analyses of the very complex multi-spin, second-order spectra. Some of the 13C NMR chemical shift assignments of these compounds reported in the literature should be changed, based on these accurate 1H NMR spectral analyses and carbon-proton chemical shift correlated spectra (COSY). The new assignments are supported by the 1J(C, H) values, which show a strong dependence on the bond ang…

1H, 13C and 15N NMR spectral characterization of twenty-seven 1,2-diaryl-(4E)-arylidene-2-imidazolin-5-ones.

1H, 13C and 15N NMR chemical shifts and couplings nJ(H,C) in DMSO-d6 at 30 °C have been determined for 1,2-diaryl-(4E)-arylidene-2-imidazolin-5-one derivatives 1–27. Their chemical shift assignments are based on PFG DQF 1H,1H COSY, PFG 1H,13C HMQC as well as PFG 1H,13C and 1H,15N HMBC experiments. For compounds 1–10 including aryl fluorine substituent(s) also the couplings nJ(F,C) (n = 1 − 4) are reported. Copyright © 2006 John Wiley & Sons, Ltd.

NMR spectroscopy in environmental chemistry:1H and13C NMR parameters of tricyclic polychlorinated C10 hydrocarbons and their oxy derivatives based on two-dimensional NMR techniques

Two-dimensional homo- and heteronuclear NMR chemical shift correlation techniques were applied in the characterization of five tricyclic polychlorinated C10 hydrocarbons, chlordene (1), heptachlor (2), trans-nonachlor (3), α-chlordene (4) and γ-chlordene (5), which are spread globally in the environment owing to their use as insecticides. Approximate and partly contradictory 1H and 13C NMR chemical shifts reported in the literature were corrected in this work. The chemical shift assignments of 1–5 were based on DQF COSY, HMQC and HMBC experiments. In addition, an INADEQUATE experiment was needed to ascertain the 13C chemical shifts assignment of 2. The nJ(H,H)s of 1–5 were solved by compute…

Molecular Pacman: Folding, Inclusion, and X-ray Structures of Tri- and Tetraamino Piperazine Cyclophanes

Reaction of piperazine and 1,3-bis(bromomethyl)-2-nitrobenzene under high-dilution conditions yields cyclic trimeric trinitro, tetrameric tetranitro, and pentameric pentanitro piperazine cyclophanes. Reduction of the nitro groups with SnCl(2) under acidic conditions produces the corresponding triamino and tetraamino piperazine cyclophanes. The solution studies of both nitro and amino piperazine cyclophanes at 30 degrees C by (1)H NMR spectroscopy shows symmetrical structures owing to the fast conformational exchange, whereas the low temperature studies of the tetraamino piperazine cyclophane reveals interesting dynamic behavior that indicates additional intramolecular interactions. Careful …

ChemInform Abstract: High-Resolution Solid-State NMR Spectroscopy of Steroids and Their Derivatives

Abstract: Steroids are an important class of organic compounds containing a vast array of biologically and physiologically essential molecules. Due to their availability, relatively straightforward derivatizability, and endogeneity, they are widely used in pharmacological applications. The investigation of molecular and physicochemical properties of active pharmaceutical ingredients (APIs) in the solid state is important, because these properties are directly related to their pharmacological activity. Several methods are available for this purpose. Solid-state NMR spectroscopy offers a nondestructive and flexible technique, providing both structural and dynamic information. It can be applie…

Synthesis and Structural Characterization of Substituted 2-Phenacylbenzoxazoles

1 H and 13C NMR spectra of eleven 2-phenacylbenzoxazoles (ketimine form) show that their CDCl3-solutions contains also (Z)-2-(benzo[d]oxazol-2-yl)-1-phenylethenols (enolimine form). Intramolecular hydrogen bonding in the latter tautomer was found to be significantly weaker than that one in respective (Z)-2-(2-hydroxy-2-phenylvinyl)pyridines. Integrals of the 1 H NMR signals were used to evaluate the molar ratio of the tautomers. Strong electron-donating substituents were found to stabilize the ketimine tautomer. pKT (negative logarithm of the equilibrium constant, KT = [ketimine]/[enolimine]) was found to be linearly dependent on the Hammett substituent constant σ. The results of the MP2 ab…

Synthesis and characterisation of N-glycosyl amines from the reaction between 4,6-O-benzylidene-D-glucopyranose and substituted aromatic amines and also between 2-(o-aminophenyl)benzimidazole and pentoses or hexoses.

Twelve N-glycosyl amines were synthesised using 4,6-O–benzylidene-D-glucopyranose and different substituted aromatic amines, including some diamines that resulted in bis-glycosyl amines. Another set of six N–glycosyl amines was synthesised using different hexoses and pentoses and 2–(o–aminophenyl)benzimidazole. All compounds were isolated as solid products and purified, their elemental compositions were established, and these were characterised by NMR (1H and 13C), UV–Vis, and FTIR spectroscopy, by FAB mass spectrometry (molecular-ion peaks gave molecular weights), and by their optical rotations. While the protected saccharide, 4,6-O-benzylidene-D-glucopyranose, exists as a mixture of β and…

Evidence of Weak Halogen Bonding: New Insights on Itraconazole and its Succinic Acid Cocrystal

Exact knowledge of the crystal structure of drugs and lead compounds plays a significant role in the fields of crystal engineering, docking, computational modeling (drug–receptor interactions), and rational design of potent drugs in pharmaceutical chemistry. The succinic acid cocrystal of the systemic antifungal drug, itraconazole, reported by Remenar et al. (J. Am. Chem. Soc.2003, 125, 8456–8457) (CSD: IKEQEU), represents one of the classical examples displaying a molecular fitting mechanism in the solid state. In this work, we disclose the X-ray single-crystal structure of the cis-itraconazole–succinic acid (2:1) cocrystal and found that it differs slightly from the previously reported st…

Bile Acids. Toxicology and Bioactivity. Edited by Gareth J. Jenkins and Laura J. Hardie.

17O NMR and molecular mechanical studies of arylmethylenemalonaldehydes

The 17O NMR spectra of six different arylmethylenemalonaldehydes were measured for various solvents and temperatures. The 17O NMR chemical shifts and line widths of the carbonyl oxygens of the malonaldehyde fragment show a clear variation in the series of monoaryl compounds studied. The differences between the 17O NMR chemical shifts of the formyl oxygens correlate well with two conformationally dependent 1H–1H and 1H–13C coupling constants for the same compounds. Molecular mechanical calculations were also performed in order to relate the present data with the conformational preferences of the malonaldehyde fragment of the arylmethylenemalonaldehydes.

Synthesis of Both Ionic Species of Ammonium Dithiocarbamate Derived Cholic Acid Moieties

The reaction of 3-aminopropylamide of cholic acid with CS2 produced a bile acid derivative of dithiocarbamic acid which further formed an ammonium salt with another molecule of 3-aminopropylamide of cholic acid. The cationic 3-ammonium propylamide of cholic acid did not react further with CS2 and the formed salt was stable in the reaction mixture, even when excess CS2 was used. When the reaction was carried out in the presence of aqueous sodium hydroxide, only the bile acid derivative of sodium dithiocarbamate was formed. The dithiocarbamate derivatives were characterized by 1H- and 13C-NMR spectroscopy and ESI-TOF mass spectrometry.

Porphyrin-bile acid conjugates: from saccharide recognition in the solution to the selective cancer cell fluorescence detection.

This paper describes the preparation and use of conjugates of porphyrins and bile acids as ligands to bind to tumor expressed saccharides. Bile acid-porphyrin conjugates were tested for recognition of saccharides that are typically present on malignant tumor cells. Fluorescence microscopy, in vitro PDT cell killing, and PDT of subcutaneous 4T1 mouse tumors is reported. High selectivity for saccharide cancer markers and cancer cells was observed. This in vivo and in vitro study demonstrated high potential use for these compounds in targeted photodynamic therapy.

1H,13C and15N NMR chemical shifts of substituted pyrazolo[1,5-a]pyrimidines

A new potential toxaphene congener: synthesis, GC/EI-MS study, crystal structure, NMR analysis, and ab initio calculations of 3-endo,5-endo-dichloro-7,7-bis-chloromethyl-4-dichloromethyl-tricyclo[2.2.1.02,6]heptane

Abstract A new potential toxaphene congener 3- endo ,5- endo -dichloro-7,7-bis-chloromethyl-4-dichloromethyl-tricyclo[2.2.1.0 2,6 ]heptane 2 has been isolated from reaction mixture obtained by the chlorination of 2- exo ,10,10-trichlorobornane 1 . The X-ray structural analysis of 2 revealed an unusual tricyclic structure, where the two chlorine atoms occupying endo -positions are in close spatial proximity with each other and near to the neighbouring CHCl 2 group. Further, it revealed that the symmetry of the molecule is distorted. The 1 H and 13 C NMR spectra of 2 have been assigned by means of 1 H, 1 H d ouble- q uantum f iltered co rrelation s pectroscop y (DQF COSY), PFG 1 H, 13 C HMQC …

Conformational equilibrium in supramolecular chemistry: Dibutyltriuret case

The association of substituted benzoates and naphthyridine dianions was used to study the complexation of dibutyltriuret. The title molecule is the simplest molecule able to form two intramolecular hydrogen bonds. The naphthyridine salt was used to break two intramolecular hydrogen bonds at a time while with the use of substituted benzoates the systematic approach to study association was achieved. Both, titrations and variable temperature measurements shed the light on the importance of conformational equilibrium and its influence on association in solution. Moreover, the associates were observed by mass spectrometry. The DFT-based computations for complexes and single bond rotational barr…

1 H,13 C, 19 F NMR, and ESI mass spectral characterization of two geminal difluorosteroids

Two geminal difluorosteroids, 3,3-difluoro-5β-cholan-24-oic acid (1) and 3,3-difluoro-5α-androstan-17-one (2), have been prepared from corresponding ketosteroids with diethylaminosulphurtrifluoride (DAST) treatment in moderate yields. The structures of 1 and 2 have been characterized by 1H, 13C, 19F NMR, and ESI mass spectral techniques. Copyright © 2008 John Wiley & Sons, Ltd.

Comparative NMR and IR spectral, X-ray structural and theoretical studies of eight 6-arylidenedibenzo[b,e]thiepin-11-one-5,5-dioxides

Abstract Eight 6-arylidenedibenzo[b,e]thiepin-11-one-5,5-dioxides are characterized by NMR and IR spectroscopy. Single crystal X-ray structures for three congeners are reported. In addition, the transmission of substituent effects in conjugated double bond system of 6-arylidenedibenzo[b,e]thiepin-11-one-5,5-dioxide framework has been evaluated by calculating the correlations between selected 13C NMR chemical shifts and IR stretching wave numbers and Hammett constants of the substituents locating in the phenyl ring of the arylidene moiety.

Comparison of calculated DFT/B3LYP and experimental 13C and 17O NMR chemical shifts, ab initio HF/6-31G* optimised structures, and single crystal X-ray structures of some substituted methyl 5β-cholan-24-oates

Abstract Single crystal X-ray structures (monoclinic space group P2 1 ) for methyl 3-oxo-5β-cholan-24-oate and methyl 3,12-dioxo-5β-cholan-24-oate have been solved and compared with HF/6-31G* optimised structures. In the crystalline packings the side chains are connected with weak OC(sp 3 ) H ⋯ O -type of interactions between C25– H and C24– O –C25 and the keto ends with weak C(sp 3 ) H ⋯ O C-type of interactions between C4– H and O C3. The orientations of the side chains, which steric configurations are of great importance to the biological activity of the molecules, are compared with the experimental structure of methyl 3α-hydroxy-5β-cholan-24-oate. Probable reasons for the observed dif…

Highly water repellent aerogels based on cellulose stearoyl esters

Herein we combine in a novel way the physical effect of porous structure of a cellulosic aerogel with the chemical effect of long alkyl tails by a well known homogeneous green esterification method, to achieve purely bio-based and highly water repellent cellulosic materials. As an alternative for a traditional fluoro derivatized hydrophobization, here long fatty acid tails are utilized to lower the surface energy. To minimize the process emission, ionic liquid (IL) 1-allyl-3-methylimidazolium chloride is used for the esterification, due to its non-volatility and recyclability. We have shown here that low degree of substitution (DS) of the fatty acid cellulose material enables the spontaneou…

Supramolecular Adducts of Ferrocene and Five Bile Acid Derived Triolides

Formation of supramolecular adducts of ferrocene (guest) and cyclic head-to-tail trimers (hosts) derived from bile acid: 3α-hydroxy-5β-cholan-24-oic acid triolide (1), 3α-hydroxy-7-oxo-5β-cholan-24-oic acid triolide (2), 3α-hydroxy-12-oxo-5β-cholan-24-oic acid triolide (3), 3α-hydroxy-7α-trifluoroacetoxy-6β-cholan-24-oic acid triolide (4) and 3α-hydroxy-12α-TFA-5β-cholan-24-oic acid triolide (5) (TFA = trifluoroacetoxy) have been studied by 1H NMR. The best computer-assisted data fitting on the 1H-NMR chemical shift data was given by a 1:2 (guest/host) association model. The association constants vary in the range 170–990 M−1, 7-oxo-substituted triolide 2 and 12α-TFA triolide 5 showing the …

Long-range substituent and temperature effect on prototropic tautomerism in 2-(acylmethyl)quinolines

Tautomeric equilibria between 2-(cinnamoylmethyl)quinoline, (Z)-1,2-dihydro-2-(cinnamoylmethylene)quinoline and (Z)-4-phenyl-1-(2-quinolyl)-1,3-butadien-2-ol were studied by 1H, 13C and 15N NMR methods. The —CHCH— fragment conjugated with phenyl and a strong electron donor p-(1-pyrrolidine) substituent were found to favour the enolimine tautomer. This undergoes fast exchange (on the NMR time-scale) with the enaminone form. The amount of the latter tautomer was found to increase at low temperatures. Copyright © 2001 John Wiley & Sons, Ltd.

Synthesis, characterization and thermal properties of nine quaternary dialkyldiaralkylammonium chlorides

Abstract Nine R 2 R 2 ′ N + Cl − (R=benzyl, 2-methylbenzyl, 3-methylbenzyl, 4-methylbenzyl, 2-phenylethyl or 3-phenylpropyl; R′=ethyl or methyl) quaternary dialkyldiaralkylammonium chlorides were synthesized by treating dimethylformamide or diethylformamide with non-substituted or substituted arylalkyl (aralkyl) halide in the presence of sodium carbonate. The 1H NMR, 13C NMR spectroscopy, mass spectroscopy and elemental analysis were used to characterize the synthesized products. The crystal structures of six compounds were determined by X-ray single crystal diffraction. Four of the compounds crystallized in monoclinic space groups C2/c and P21/c (or P21/n), one in triclinic space group P−1…

Benson group additivity values of phosphines and phosphine oxides : Fast and accurate computational thermochemistry of organophosphorus species

Composite quantum chemical methods W1X-1 and CBS-QB3 are used to calculate the gas phase standard enthalpy of formation, entropy and heat capacity of 38 phosphines and phosphine oxides for which reliable experimental thermochemical information is limited or simply nonexistent. For alkyl phosphines and phosphine oxides, the W1X-1 and CBS-QB3 results are mutually consistent and in excellent agreement with available G3X values and empirical data. In the case of aryl-substituted species, different computational methods show more variation, with G3X enthalpies being furthest from experimental values. The calculated thermochemical data are subsequently used to determine Benson group additivity co…

Solid-State NMR, X-ray Diffraction, and Thermoanalytical Studies Towards the Identification, Isolation, and Structural Characterization of Polymorphs in Natural Bile Acids

Combined solid-state NMR, powder, and single crystal X-ray diffraction, as well as thermoanalytical studies were performed towards the identification, isolation, and structural characterization of ...

Transmission of electronic effects in 4-aryl-2,6-diphenylpyrylium perchlorates and related compounds

Identity Double-Proton Transfer in (3Z)-3-Hydroxy-1,4-di(quinolin-2-yl)but-3-en-2-one

Although there is a very fast (on the NMR timescale) double-proton transfer in (1Z,3Z)-3-hydroxy-4-quinolin-2-yl-1-quinolin-2(1H)-ylidenbut-3-en-2-one (the product of the condensation of ethyl oxalate with 2-lithiomethylquinoline), it is the only species present in chloroform solution. Comparison of the product of condensation of ethyl oxalate with 2-lithiomethyl derivatives of pyridine (recent studies) and quinoline (present studies) shows that benzoannulation considerably affects the tautomeric equilibrium. The observed changes are not only quantitative but also qualitative. Moreover, contrary to the proton transfer in the pyridine tautomers, this process is fast in the quinoline tautomer…

(Z)-Ethyl 2-oxo-3-(1,2-dihydroquinolin-2-ylidene)propanoate

Both independent molecules in the asymmetric unit of the tautomeric title compound, C14H13NO3, a synthetic product obtained from 2-lithiomethylquinoline and diethyl oxalate, crystallize in the enaminone form with a Z configuration around the double bond. Intramolecular N—H...O hydrogen bonds occur, generating an S(6) graph-set motif. In the crystal, weak intermolecular C—H...O and π–π stacking interactions [centroid–centroid distances = 3.7020 (14)–3.7429 (13)Å] define a three-dimensional supramolecular network.

Multivariate correlation between13C and31P NMR spectral data on dissolved lignin and the combustion properties of kraft black liquor

A correlative IR, MS, 1H, 13C and 15N NMR and theoretical study of 4-arylthiazol-2(3H)-onesElectronic supplementary information (ESI) available: NMR data, including graphs; Cartesian coordinates for 3a and 4. See http://www.rsc.org/suppdata/p2/b1/b106322g/

Sixteen 4-arylthiazol-2(3H)-ones (3) were synthesised by cyclisation of α-thiocyanatoacetophenones (1) in acid solution. They appear to prefer greatly the oxo tautomeric forms. In CCl4 solution an equilibrium between the free CO bond and a “dimeric” hydrogen-bonded form exists in which the latter predominates. Several IR and NMR (1H, 13C and 15N) spectral properties are shown to correlate with Hammett σ-values and/or atomic Mulliken charges and bond orders, the latter being estimated by PM3 or AM1 semiempirical methods. The electron-impact mass spectra were also recorded and the fragmentation mechanisms interpreted in terms of the energetics of the ionic species. In addition, the geometric …

Schiff-Base Podates – X-ray, NMR and Ab Initio Molecular-Orbital Studies of the Cadmium(II) Complexes of Linear and Three-Armed Podands in Solution and Solid State

Cadmium(II) complexes of two Schiff bases, 1,3-di(pyridine-2-carboxaldimino)propane (C15H16N4, L1)[1] and tris[4-(2′-pyridyl)-3-aza-3-butenyl]amine (C24H27N7, L2)[2] are described. An efficient route utilising molecular sieves for the synthesis of Schiff bases is presented. The ligands L1 and L2 can be described as linear and three-armed podands, respectively, L1 being conformationally flexible and L2 preorganised. Cadmium perchlorate in methanol with L1 yields a crystalline complex [Cd(L1)2](ClO4)2 (1), the structure of which was determined by X-ray structure analysis. The complex 1 has an unusual nonsymmetrical 8-coordinated helical structure and crystallizes in an acentric space group (C…

Macrocycles prepared from lithocholic acid, piperazine and isomeric pyridine dicarboxylic acids and their selective affinities towards sodium and potassium

Abstract Two novel macrocycles prepared from lithocholic acid, piperazine and pyridine dicarboxylic acids (2,6- and 3,5-isomers), have been characterized by 13C NMR and ESI–MS techniques. In case of the pyridine-2,6-dicarboxylate derivative, the molecular formula of the cycle was C59H87O6N3 (I), while the pyridine-3,5-dicarboxylate derivative (II) was a trimeric structure by molecular mass when compared with I. Furthermore, cycle I showed a special affinity towards potassium cation, while II possessed significant proton and sodium cation recognition properties.

Comparison of epimeric methyl lithocholate and methyl iso-lithocholate molecules: single crystal X-ray structure of methyl lithocholate, ab initio HF/6-31G* optimized structures and experimental and calculated DFT/B3LYP 13C NMR chemical shifts

Abstract 13 C NMR chemical shifts have been measured and assigned for epimeric methyl 3α/β-hydroxy-5β-cholan-24-oates (methyl lithocholate [3α-OH epimer] and methyl iso-lithocholate [3β-OH epimer]). Their molecular dynamics simulations suggest that for both epimers there exists two predominant gas phase conformations, which have been further forwarded for ab initio/HF optimizations and DFT/GIAO based 13 C NMR chemical shift calculations. Excellent linear relationships have been observed between experimental and calculated 13 C NMR chemical shifts for both epimers. For methyl lithocholate (MeLC), the other minimum energy conformation equates very well with the single crystal X-ray structure …

Spectral and structural studies on Ni(II) dithiocarbamates: Nickel sulfide nanoparticles from a dithiocarbamate precursor

Abstract Three new planar Ni(II) dithiocarbamate complexes; [Ni(4-dpmpzdtc)2] (1), [Ni(4-dpmpzdtc)(PPh3)(NCS)] (2) and [Ni(bupcbzdtc)(PPh3)(NCS)] (3) (where, 4-dpmpzdtc = 4-(diphenylmethyl)piperazinecarbodithioato anion, bupcbzdtc = N-butyl-N-(4-chlorobenzyl))dithiocarbamato anion and PPh3 = triphenylphosphine) with “NiS4” and “NiS2PN” chromophore units were synthesized and characterized by single crystal X-ray structural analysis as well as UV–Vis, IR and NMR (1H, 13C and 31P) spectroscopy. For 2, 1H–1H COSY spectrum was also recorded. Single crystal X-ray structural analysis of 1–3, reveals a slightly distorted square planar geometry in all three complexes wherein the steric and electroni…

Characterization of used mineral oil condition by spectroscopic techniques

Optical absorption, fluorescence, and quantitative 13C NMR spectroscopy have been used to study the degradation of mineral gearbox oil. Samples of used oil were collected from field service. Measured absorption, fluorescence, and quantitative 13C NMR spectra of used oils show characteristic changes from the spectra of a fresh oil sample. A clearly observable, approximately 20-nm blueshift of the fluorescence emission occurs during the early stages of oil use and correlates with changes in intensity of some specific 13C NMR resonance lines. These changes correlate with oil age because of the connection between the blueshift and breaking of the larger conjugated hydrocarbons of oil as a resul…

NMR spectroscopy: Basic principles, concepts, and applications in chemistry

Bis(6-thioxo-1,6-dihydropurinium) tetrachlorozincate(II).

The title salt, (C(5)H(5)N(4)S)(2)[ZnCl(4)], consists of two 6-thioxo-1,6-dihydropurinium (6mpH(2)(+)) cations (A and B) and a tetrachlorozincate anion, which are held together by N-H...Cl and C-H...Cl interactions. There is an anion-pi interaction between one Cl atom of the [ZnCl(4)](-) anion and the pyrimidine ring of the 6mpH(2)(+)(B) cation. Intermolecular pi-pi stacking interactions allow 6mpH(2)(+)(A) cations to form antiparallel pairs. One interesting structural feature is the double N-H...N intermolecular hydrogen bonds between two 6mpH(2)(+)(A) cations. This kind of interaction, mimicking that of natural nucleobases, can be very valuable in designing new therapeutic purine derivati…

Ab initio study of halogenated diphenyl ethers. NMR chemical shift prediction

Packing incentives and a reliable N–H⋯N–pyridine synthon in co-crystallization of bipyridines with two agrochemical actives

The co-crystallization of agrochemical actives thiophanate-methyl and thiophanate-ethyl with 2,2′-bipyridine, 4,4′-bipyridine and 1,2-bis(4-pyridyl)ethane was investigated with conventional crystallization, the slurry method and liquid-assisted grinding. Co-crystals of both thiophanates with all bipyridines were found and the structures solved with single crystal X-ray diffraction. Whereas the 2,2′-bipyridine co-crystals seem to form because of a combination of weak interactions, and in the case of the thiophanate-methyl, partly because of close packing incentives, the 4,4′-bipyridine and 1,2-bis(4-pyridyl)ethane co-crystals form mainly because of a favourable N–H···N–pyridine hydrogen bond…

Synthesis and NMR characterization of seven new substituted pyridine N-oxides

Abstract Seven 3-substituted (alkylamino, alkylnitramino and alkylnitrosoamino) derivatives of pyridine N-oxide have been prepared and their 1H, 13C and 15N NMR chemical shifts assigned based on PFG 1H, 13C HMQC and PFG 1H, X (X = 13C or 15N) HMBC experiments. In the sterically most crowded congener, 3-ethylnitramino-4-nitropyridine N-oxide, chemical non-equivalence or diastereotopicity of the N–CH2 protons was observed probably due to the chirality of the adjacent amino nitrogen caused by its restricted inversion. The coalescence temperature for the 1H NMR chemical shifts of these geminal protons has been determined and the corresponding ΔG∗ for the energy barrier of the dynamic process ha…

Solid state structural studies of five bile acid derivatives

Five synthetically important bile acid derivatives have been characterized by 13 C CP-MAS, X-ray diffraction (both single crystal and powder), FTIR, and thermoanalytical (DSC and TG) methods. The crystallinity of all these derivatives is high, which can be deducted from the 13 C CP-MAS and powder X-ray diffraction data. Two of the compounds showed polymorphism, and one polymorph was structurally elucidated for both by comparing single crystal and powder X-ray diffraction data.

NMR and quantum chemical studies on association of 2,6-bis(acylamino)pyridines with selected imides and 2,2′-dipyridylamine

Association constants of 2,6-bis(alkylcarbonylamino)pyridines (alkyl = methyl or ethyl) and their perfluoroalkyl analogues with succin- and maleimide as well as with 2,2′-dipyridylamine (complementary DAD and ADA hydrogen bonding motifs are responsible for formation of the associates) have been determined by NMR titrations and quantum chemical calculations. Interactions of 2,6-bis(alkylcarbonylamino)pyridines with imides differ by character from these of perfluoroalkyl analogues. Such large difference was not observed for the 2,2′-dipyridylamine associates. Since fluorine atoms cause carbonylamino groups to be stronger hydrogen bond donors, perfluorinated species of this type were found to …

Supramolecular architectures formed by co-crystallization of bile acids and melamine

Supramolecular multicomponent crystals constructed from three different bile acids (viz. lithocholic, deoxycholic and cholic acid) and melamine have been prepared and the non-covalent interactions in the crystals studied. Both salts and co-crystals were found. While deoxycholic and cholic acid co-crystallized with melamine as a 1 : 1 isostructural molecular complexes in space group C2, lithocholic acid formed with melamine a 2 : 1 molecular complex in space group P21. This is the first report on a multicomponent crystal structure containing lithocholic acid.

Structural studies of five novel bile acid-4-aminopyridine conjugates

Abstract Synthesis and solid-state structural characterization of five bile acid amides of 4-aminopyridine (4-AP) are reported. Systematic crystallization experiments revealed a number of structural modifications and/or solvate/hydrate systems for these conjugates. Particularly, cholic acid conjugate exhibited five distinct structure modifications, including one anhydrous form, mono- and dihydrates, as well as ethanol and 2-butanol solvates. The obtained crystal forms were examined extensively with various analytical methods, including solid-state NMR, Raman, and IR spectroscopies, powder and single crystal X-ray diffraction methods, thermogravimetry, and differential scanning calorimetry. …

Bile acid–amino acid ester conjugates: gelation, structural properties, and thermoreversible solid to solid phase transition

Design, synthesis, and gelation properties of three novel biocompatible bile acid–L-methionine methyl ester conjugates are presented. Two of the conjugates have been shown to undergo self-assembly leading to organogelation in certain aromatic solvents. The properties of these gels have been investigated by conventional methods typical for molecular gel studies along with 13C CPMAS NMR spectroscopic studies of the native gel. In addition, properties in solid and solution states for all three compounds have been investigated, and single crystal X-ray structures of all compounds determined. Furthermore, powder X-ray diffraction studies have revealed that compound 1 undergoes a dynamic and reve…

Steroid-based gelators of A(LS)2 type: Tuning gel properties by metal coordination

By utilizing up-to-date knowledge about gelators, we designed and synthesized a novel low-molecular-weight gelator bearing a pyridine-2,6-dicarboxylic acid moiety and two cholesteryl glycinate units. In order to demonstrate the ingenuity of our design, we prepared a series of structurally related compounds and studied their gelation properties. Based on the results, we determined structural features of the gelator molecules which were important for successful gel formation. We showed that the properties of the gel systems (transparency, morphology, etc.) can be tuned by coordination with different metal ions, as well as by changing the solvent. Gelators, and their gels and xerogels were stu…

Secondary interactions as driving force in heterocomplex formation of 2,7-disubstituted-1,8-naphthyridines: Quantum chemical, NMR and mass spectral investigations

Abstract Tautomerism and dimerization of 2,7-disubstituted-1,8-naphtyridines has been studied theoretically by quantum chemical methods and experimentally by liquid and solid state NMR and ESI-TOF mass spectral techniques. The heterocomplex formation has been proven in solution by variable temperature 1H NMR and in solid state by 13C CPMAS NMR spectra of a grinded mixture of two congeners. Secondary interactions have been proposed as driving forces in the heterocomplex formation. The energy differences between homo- and heterocomplexes were calculated with recently developed DFT + D methods. The energy data obtained by the quantum chemical methods are in agreement with the concept of second…

NMR Quantification of Tautomeric Populations in Biogenic Purine Bases

Purine bases such as purine, adenine, hypoxanthine, and mercaptopurine are known to exist in several tautomeric forms. Characterization of their tautomeric equilibria is important not only for predicting the regioselectivity of their N-alkylation reactions but also for gaining knowledge of the patterns with which these compounds of significant biological activity form hydrogen bonds with their biological targets. Low-temperature 1H- and 13C-NMR spectroscopy were used to investigate the tautomeric equilibria for purine and some purine derivatives in methanol and N,N-dimethylformamide solutions. The N(7)H and N(9)H tautomeric forms were quantified by integrating the individual 1H NMR signals …

On the exhaust of electromagnetic drive

Recent reports about propulsion without reaction mass have been met on one hand with enthusiasm and on the other hand with some doubts. Namely, closed metal cavities, when fueled with microwaves, have delivered thrust that could eventually maintain satellites on orbits using solar power. However, the measured thrust appears to be without any apparent exhaust. Thus the Law of Action-Reaction seems to have been violated. We consider the possibility that the exhaust is in a form that has so far escaped both experimental detection and theoretical attention. In the thruster's cavity microwaves interfere with each other and invariably some photons will also end up co-propagating with opposite pha…

Studies on supramolecular gel formation using DOSY NMR

Herein, we present the results obtained from our studies on supramolecular self-assembly and molecular mobility of low-molecular-weight gelators (LMWGs) in organic solvents using pulsed field gradient (PFG) diffusion ordered spectroscopy (DOSY) NMR. A series of concentration-dependent DOSY NMR experiments were performed on selected LMWGs to determine the critical gelation concentration (CGC) as well as to understand the behaviour of the gelator molecules in the gel state. In addition, variable-temperature DOSY NMR experiments were performed to determine the gel-to-sol transition. The PFG NMR experiments performed as a function of gradient strength were further analyzed using monoexponential…

13C NMR spectroscopic study of diphenyl ether and 28 of its polychlorinated derivatives

The 13 C NMR chemical shifts and coupling constants for diphenyl ether and 28 environmentally interesting polychlorinated diphenyl ethers were measured and analysed

Preparation, reactivity and tautomeric preferences of novel (1H-quinolin-2-ylidene)propan-2-ones

1,1-Difluoro-3-(1H-quinolin-2-ylidene)propan-2-one 1a, 1,1,1-trifluoro-3-(1H-quinolin-2-ylidene)propan-2-one 1b, 1,1,1-trifluoro-3-(4-chloro-1H-quinolin-2-ylidene)propan-2-one 1c and 1,3-dibromo-1,1-difluoro-3-(2-quinolyl)propan-2-one 2 are prepared and characterized by various spectroscopic techniques. The crystal structure of 1a is determined by X-ray diffraction. Furthermore, a series of previously known non-halogenated (1H-quinolin-2-ylidene)propan-2-ones 1d-1h are oxidized with AgBrO3 in the presence of AlCl3. In all cases, 2-(1-bromo-1-chloromethyl)quinoline 3 is obtained in high yield. The bromination order and sites of 1a are analyzed based on ab initio MP2 and DFT calculations for …

Substituent Effect in 2-Benzoylmethylenequinoline Difluoroborates Exhibiting Through-Space Couplings. Multinuclear Magnetic Resonance, X-ray Diffraction, and Computational Study

The series of nine 2-benzoylmethylenequinoline difluoroborates have been synthesized and characterized by multinuclear magnetic resonance, X-ray diffraction (XRD), and computational methods. The through-space spin-spin couplings between (19)F and (1)H/(13)C nuclei have been observed in solution. The NMR chemical shifts have been correlated to the Hammett substituent constants. The crystal structures of six compounds have been solved by XRD. For two derivatives the X-ray wave function refinement was performed to evaluate the character of bonds in the NBF(2)O moiety by topological and integrated bond descriptors.

Direct determination of tautomerism in purine derivatives by low-temperature NMR spectroscopy

An investigation of the purine derivatives N,N-dimethyl-N'-(7(9)-H-purin-6-yl)-formamidine, 6-chloropurine and 6-methoxy purine at low temperatures by NMR spectroscopy has been carried out. Low temperature enabled us in two cases to detect the separate NMR signals of N7-H and N9-H tautomers.

Two (E)-2-({[4-(dialkylamino)phenyl]- imino}methyl)-4-nitrophenols

The slow evaporation of analytical NMR samples resulted in the formation of crystals of (E)-2-({[4-(dimethyl­amino)­phenyl]­imino}­methyl)-4-nitro­phenol, C15H15N3O3, (I), and (E)-2-({[4-(diethyl­amino)­phenyl]­imino}­methyl)-4-nitrophenol, C17H19N3O3, (II). Despite the small structural difference between these two N-salicylidene­aniline derivatives, they show different space groups and diverse mol­ecular packing. The mol­ecules of both compounds are close to being planar due to an intra­molecular O-H...N hydrogen bond. The 4-alkyl­amino-substituted benzene ring is inclined at an angle of 13.44 (19)° in (I) and 2.57 (8)° in (II) with respect to the 4-nitro-substituted phenol ring. Only very…

1H,13C,17O NMR and IR spectroscopic study of all methyl chloropropanoates

1 H, 13 C and 17 O NMR chemical shifts, n J(H,H) and n J(C,H) spin-spin coupling constants and IR absorption maxima and intensities for the most characteristic bands of methyl propanoate and all eleven chloropropanoic acid methyl esters are reported

Wasserstoffbrücken-gebundene Analoga von Cavitanden

Conformational and Tautomeric Control by Supramolecular Approach in Ureido-N-iso-propyl,N’-4-(3-pyridin-2-one)pyrimidine

Ureido-N-iso-propyl,N&rsquo

Synthesis, characterization, and thermal behavior of steroidal dendrons

A series of novel dendritic steroidal polyesters of first and second generation has been synthesized in convergent fashion by the use of 2,2-bis(hydroxymethyl)propionic acid as a repeating unit. The first- and second-generation hydroxy-functionalized dendrons with a variety of surface modifications were produced through the use of four bile acids: lithocholic acid (LCA), ursodeoxycholic acid (UDCA), deoxycholic acid (DCA), and cholic acid (CA). The thermal behavior of the steroidal dendrons was characterized by differential scanning calorimetry (DSC) and by thermogravimetric analysis (TGA). Finally, quantum chemical calculation methods were used to study the geometries of the dendrons and t…

Association of 2-acylaminopyridines and benzoic acids. Steric and electronic substituent effect studied by XRD, solution and solid-state NMR and calculations

Abstract Eight single crystal X-ray structures, solid-state NMR spectroscopic, and theoretical studies utilizing QTAIM methodology were used to characterize the 2-acyl (alkyl in acyl = methyl, ethyl, t-butyl, and 1-adamantyl) amino-6-R-pyridine/4-R′-benzoic acid (R,R′ = H or Me) cocrystals. As expected among alkyl groups 1-adamantyl due to its bulkiness has the most significant effect on the relative positions of molecules in cocrystals. In addition, the subtle electronic and steric effects by the methyl substituents were observed. The theoretical calculations with full geometry optimizations are in agreement with the experimental findings (geometry, energy of hydrogen bonds). Based on the …

1H,13C and17O NMR study of chlorovanillins and some related compounds

1H, 13C and 17O NMR chemical shifts and nJ(H,H), 1J(C,H) and 3J(C-6, H-formyl) spin—spin coupling constants of chlorinated vanillins (3-methoxy-4-hydroxybenzaldehydes) were determined. The variation in the long-range 4J(H,H) value between the formyl proton and an ortho-proton suggests that the ortho-substituent strongly forces the formyl group out of the aromatic plane. This can also be observed by considering the 3J(C-6,H-formyl) values and the 13C and 17O NMR chemical shifts. The 17O NMR chemical shifts show a linear correlation with the torsion angle of the formyl group calculated by molecular mechanics. The 13C and 17O NMR chemical shifts of the methoxyl group also possess strong predic…

Mannich Reactions with Amino Alcohols

The condensation of resorcarenes 1 with various amino alcohols and an excess of formaldehyde was studied. The tetrabenzoxazines 2a−e were found as the only products in the reaction with 6-aminohexan-1-ol, 4-aminobutan-1-ol, and 2-aminoethanol, while 3-aminopropan-1-ol forms the tetraoxazine 3 as the main product. In the case of aminoethanols substituted at the 2-position with alkyl groups, the tetraoxazolidines 4 are the preferred reaction products, while 1-methyl aminoethanol (1-amino-propan-2-ol) yields predominantly the tetrabenzoxazine 2f. The structures of all these compounds have been confirmed by NMR spectroscopy and additionally by single-crystal X-ray analysis in the case of 2a and…

Novel two-step synthesis of gold nanoparticles capped with bile acid conjugates

Bile acids and their conjugates are physiologically important molecules. Syntheses and structure elucidation combined with investigation of properties and applications of bile acids and their derivatives are of academic interest. The concept of using bile acids and their conjugates in nanoscience is a novel idea, which opens up fascinating prospects. In this article, an easy and simple route for obtaining N-lithocholyl-L-(cysteine ethyl ester) (3), capable of effectively capping and stabilizing metal nanoparticles, is described. The whole synthetic route needs only two steps giving a moderate to good yield. The gold NPs are characterized by elemental analysis, UV spectroscopy, and TEM. Addi…

Interaction of metal ions with N-glycosylamines: isolation and characterization of the products of 4,6-O-benzylidene-N-(o-carboxyphenyl)-β-D-glucopyranosylamine with different metal ions

Metal-ion complexes of Li+, Na+, K+, Mg2+, Ca2+, Ba2+, Pb2+, Cd2+, Hg2+ with 4,6–O–benzylidene–N–(o–carboxyphenyl)–β–D–glucopyranosylamine were synthesized and isolated as solid products and characterized by analytical means as well as by spectral techniques, such as, 1H and 13C NMR, FTIR, absorption, FAB mass spectrometry, optical rotation and CD. While the alkali metal ions formed ML type of complexes, the other metal ions formed ML2 type complexes. Molecular weights of the complexes of Li+, Na+ and K+ were established based on the molecular-ion peaks in the FAB mass spectra. The saccharide portion remians in the β-anomeric form even after the complexation. The spectral data, as well as t…

Design, synthesis and spectral studies of novel bile acid-arene conjugates: Trans to cis isomerization of azobenzene core controlled by bile acid hydrophobicity

Abstract Four bile acid-arene conjugates, 1,4-bis[dimethyl(3α,7α,12α-trihydroxy-5β-cholan-24-amidoethyl)ammoniomethyl]benzene dibromide ( 1 ), 1,3,5-tris[dimethyl(3α,7α,12α-trihydroxy-5β-cholan-24-amidoethyl)ammoniomethyl]benzene tribromide ( 2 ), bis{4-[dimethyl(3α,7α,12α-trihydroxy-5β-cholan-24-amidoethyl)ammoniomethyl]phenyl}diazene dibromide ( 3 ), and bis{4-[dimethyl(3α-hydroxy-5β-cholan-24-amidoethyl)ammoniomethyl]phenyl}diazene dibromide ( 4 ), have been synthesized in good yields, and their structures have been characterized by 1 H, 13 C, 13 C DEPT-135, PFG 1 H, 13 C HMQC, PFG 1 H, 13 C HMBC, and PFG 1 H, 15 N HMBC NMR spectra. Their molecular weights and elemental compositions have…

Characterization of electronic properties of the Cr(CO)3 group in chromium, tricarbonyl [3-[(η6-aryl)methylene]-Z-1(3H)-isobenzofuranones] using spectral and theoretical methods

Abstract The IR, 13C- and 17O-NMR spectral characteristics of the Cr(CO)3 group in a series of eight chromium, tricarbonyl[3-[(η6-aryl)methylene]-Z-1(3H)-isobenzofuranones] were correlated mutually as well as with theoretical data obtained by optimized MMX force-field and EHT calculations. The net charges on the carbon and oxygen atoms of the CO group and their differences were found as the most appropriate quantitative characteristics for the electronic properties of the Cr(CO)3 group. Using the results of the previously reported linear correlations, the electron-withdrawing effect of the PhCr(CO)3 moiety, weakened by the back-donation effect, was estimated as σα≅0.45 on the scale of Hamm…

GIAO/DFT calculated chemical shifts of tautomeric species. 2-Phenacylpyridines and (Z)-2-(2-hydroxy-2-phenylvinyl)pyridines

1H, 13C and 15N NMR chemical shifts for 28 substituted 2-phenacylpyridines (ketimine forms) and their enolimine tautomers, (Z)-2-(2-hydroxy-2-phenylvinyl)pyridines, were calculated via the GIAO/DFT approach. Among four tested methods at the B3LYP level of theory, the 6–311G, 6–311++G and 6–311G** basis sets gave acceptable result for 13C NMR chemical shifts whereas the 6–311++G** basis set was the minimum needed for reproduction of 15N NMR chemical shifts. Satisfactory reproduction of 13C and 15N NMR chemical shifts for different tautomers revealed that intramolecular hydrogen bonding could be modeled reliably by these calculations when the geometry optimizations were done with the HF/3–21G…

Multinuclear and Solid State NMR of Gels

Over the past six decades, nuclear magnetic resonance spectroscopy has been an integral part of synthetic organic and organometallic chemistry, as well as biochemistry. Beyond solution state experiments, increasing developments have opened new avenues to study materials in their solid state. Between two extremes (i.e., solution and solid), there exist several other forms of materials, especially soft materials such as gels and liquid crystals. Traditionally gels have been studied using solution state NMR spectroscopic methods. However, the viscosity of complex viscoelastic fluids such as gels affects the molecular tumbling, which in turn affects the chemical shift anisotropy and dipolar and…

First Crystallographic Investigation of Complexes of cis-VO2+, cis-MoO22+, and trans-UO22+ Species with Schiff-Base Molecules Derived from 4,6-O-Ethylidene-β-D-glucopyranosylamine

The interaction of Schiff-base ligands derived from 4,6-O-ethylidene-β-D-glucopyranosylamine with cis-VO 2 + , cis-MoO 2 2+ , and trans-UO 2 2+ species have been studied by isolating and characterizing the corresponding products. The structures of one complex of each type of species have been established by single-crystal X-ray diffraction analysis. In all the complexes, the saccharide moiety adopts a chair conformation and has a β-anomeric form. A gradual increase in coordination number (5, 6, and 7) and a gradual variation in the geometry (distorted trigonal-bipyramidal, distorted octahedral, and pentagonal-bipyramidal) are observed on going from the complexes of cis-VO 2 + (mononuclear) …

A statistical study of the additivity of substituent effects on the5J(HH) long-range coupling constant of the formyl proton in substituted benzaldehydes

The additivity of chloro and hydroxy substituent effects on the formyl proton spin-spin coupling constants with the meta ring proton, 5J(HH), has been tested with 15 chlorinated benzaldehydes and hydroxybenzaldehydes by multiple linear regression analysis. No general additivity rule was detected with whole data. Using benzaldehyde as the reference substance, a good correlation was achieved for p-hydroxybenzaldehydes. The same reference compound was not suitable for o-hydroxy derivatives; a much better correlation was observed using o-hydroxybenzaldehyde as a reference compound in the latter case.

Mn(IV) and Co(III)-complexes of –OH-rich ligands possessing O2N, O3N and O4N cores: syntheses, characterization and crystal structures

Mn(IV) and Co(III) complexes of tridentate –OH–rich ligands possessing O2N, O3N and O4N donor sets were synthesized, characterized and their structures were established by single crystal X-ray diffraction, where the binding core is O4N2. In the structurally characterized complexes, the coordination geometry about the metal ion was found to be distorted octahedral.

Four-, five- and six-coordinated Zn-II complexes of OH-containing ligands: Syntheses, structure and reactivity

Four-, five- and six-coordinated complexes of Zn-II with OH-rich molecules possessing an ONO binding core were synthesized, characterized and their structures were established by single-crystal X-ray diffraction, The corresponding metal ion geometries were found to be distorted tetrahedral, square pyramidal and octahedral, respectively. The complexes exhibit interesting lattice structures such as layered and corrugated sheets owing to the presence of a number of weak intermolecular interactions. The five-coordinated, water-bound Zn-II complex was studied because of its putative hydrolysis property towards p-nitrophenyl acetate. (C) Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.

Recent advances in steroidal supramolecular gels

During the last decade or two the interest towards small molecules capable of self-assembly leading to gelation has increased intensively. The investigation of these supramolecular gels aims not only at understanding the fundamental processes underlying gel formation but also at development of new materials with a myriad of applications. Steroids are widely-spread natural products with a large and rigid steroidal nucleus combined with derivatizable functional groups leading to an adjustable polarity profile, which makes them attractive building blocks when designing novel low molecular weight gelators. Due to their unique properties, steroid-based supramolecular gels may find use in applica…

Specificity of 15N NMR chemical shifts to the nature of substituents and tautomerism in substituted pyridine N-oxides

1H, 13C, and 15N NMR chemical shifts have been measured for 2-aminopyridine N-oxide (1), its eleven derivatives (2–10, 13, 14), and 3-Cl and 3-Br substituted 4-nitropyridine N-oxides (11, 12). δ(15N) of pyridine ring nitrogen in 2-acetylaminopyridine N-oxides are 5.9–11.5 ppm deshielded from those in 2-aminopyridine N-oxides. When amino and acetylamino substituents are in 4-position, δ(15N) of ring nitrogen is 21.3 ppm deshielded in the acetylated derivative. The strong resonance interaction between 2-amino and 5-nitro groups reflects in the decrease of amino nitrogen shielding about 5.3–17.9 ppm. Also, 1H and 13C NMR spectral data are in agreement with 15N NMR results reflected as deshield…

N-{4-[(3-Methyl-phen-yl)sulfamo-yl]phen-yl}benzamide.

In the title compound, C20H18N2O3S, the dihedral angle between the central benzene ring and the amide group is 24.1 (3)° and that between this ring and the aromatic ring of the tolyl group is 68.2 (16)°. In the crystal, adjacent molecules are linked by N—H...O hydrogen bonds into a linear chain running along [100]. Weak C—H...O contacts also occur. Extensive weak π–π interactions exist from both face-to-face and face-to-edge interactions occur between the aromatic rings [centroid–centroid distances = 3.612 (2) and 4.843 (2) Å].

Substituent and temperature controlled tautomerism of 2-phenacylpyridine: the hydrogen bond as a configurational lock of (Z )-2-(2-hydroxy-2-phenylvinyl)pyridine

2-Phenacylpyridines substituted in the benzene ring are in equilibrium with (Z)-2-(2-hydroxy-2-phenylvinyl)pyridines when dissolved in chloroform. The substituent affects significantly the tautomeric equilibrium [the amount of the enolimine form stabilized by the intramolecular hydrogen bond is 1 and 92% for R = p-N(CH2)4 and p-NO2, respectively]. The negative logarithm of the tautomeric equilibrium constant, KT, is linearly dependent on the Hammett σ substituent constants. The dependence of KTvs. temperature is exponential in character: the more electron-withdrawing is the substituent, the more distinct is the influence of temperature. Unexpectedly, the tautomer present in the crystalline …

X-ray structures of five variably tert-butoxycarbonyl-substituted adenines and their liquid and solid state NMR investigations

Abstract Adenine reacts selectively with di- tert -butyldicarbonate in THF in the presence of NaOH to give N 9-monoBoc-adenine 1 . The molecular structure and crystal packing of this and four other variably substituted Boc-derivatives of adenine were determined in solid state by means of X-ray diffraction and CP/MAS NMR experiments and characterized in liquid state by 1 H, 13 C, and 15 N NMR spectroscopy as well. Additionally, crystal structure of inclusion compound between N 6 -monoBoc-adenine 5 and CHCl 3 is reported. Tautomeric equilibria of mono- and disubstituted derivatives 4 and 5 in liquid state were studied by VT NMR experiments.

Bile acid-derived mono- and diketals—synthesis, structural characterization and self-assembling properties

Three oxo-derivatives of bile acid methyl esters have been used as starting compounds in the preparation of novel bile acid monoketals with 1,2-benzenediol (catechol) and 2,3-naphthalenediol, as well as mono- and diketals with pentaerythritol. Monoketals of pentaerythritol showed a tendency to form thermoreversible gels in many aromatic solvents and the methyl lithocholate derivative proved to be a supergelator able to form a gel with t-butylbenzene at a concentration as low as 0.5% w/v. Whereas the naphthalenediol ketals formed film-type materials in the studied solvents, the catechol ketals underwent rapid crystallization into X-ray quality single crystals. Single crystal X-ray structures…

Mono-, bi- and polynuclear complexes of dimethyldiphenylsilane, diphenylether and biphenyl with Cr, Co and Ru. Synthesis and 1H, 13C, 17O and 29Si NMR spectroscopic characterization

Abstract Mono- and bimetallic transition metal carbonyls of dimethyldiphenylsilane, Ph 2 Si(CH 3 ) 2 (L1), diphenylether, Ph 2 O (L2) and biphenyl, Ph 2 (L3): Ph 2 Si(CH 3 ) 2 Cr(CO) 3 ( 1 ), Ph 2 Si(CH 3 ) 2 [Cr(CO) 3 ] 2 ( 2 ), Ph 2 Si(CH 3 ) 2 Co 4 (CO) 9 ( 3 ), Ph 2 Si(CH 3 ) 2 [Co 4 (CO) 9 ] 2 ( 4 ), Ph 2 Si(CH 3 ) 2 Cr(CO) 3 Co 4 (CO) 9 ( 5 ), Ph 2 OCr(CO) 3 ( 6 ), Ph 2 OCo 4 (CO) 9 ( 7 ), Ph 2 ORu 6 C(CO) 14 ( 8 ), Ph 2 OCr(CO) 3 Co 4 (CO) 9 ( 9 ) and Ph 2 Ru 6 C(CO) 14 ( 10 ) have been prepared and characterized by means of 1 H, 13 C, 17 O and 29 Si NMR spectroscopy. The same order of the shielding effects induced by the transition metal (Co 1 H NMR chemical shifts of the η 6 -coord…

Subcomponent Self-Assembly A Quick Way to New Metallogels

Subcomponent self-assembly, introduced by the Nitschke group,[1] is a process which allow complex structures to be generated from simple building blocks (generally aldehydes and amines). In this bottom-up approach, the building blocks spontaneously self-assemble around templates (usually metal ions) leading to a simultaneous covalent (C=N) and dative (N– metal) bonds formation. The method has been successfully used to construct well-defined metal-organic macrocycles, helicates, catenanes, rotaxanes, grids,[2] and cages.[3] Our field of interest lies not in building-up of defined structures but in designing gelator molecules for a formation of supramolecular gels as functional nanomaterials.…

E-2-Benzylidenebenzocycloalkanones. IV. Studies on transmission of substituent effects on 13C NMR chemical shifts of E-2-(X-benzylidene)-1-tetralones, and -benzosuberones. Comparison with the 13C NMR data of chalcones and E-2-(X-benzylidene)-1-indanones

Abstract Single substituent parameter (SSP) and dual substituent parameter (DSP) analyses were applied to study the transmission of substituent effects on selected 13C NMR chemical shifts of the cyclic chalcone analogues, E-2-(4′-X-benzylidene)-1-tetralones (2) and E-2-(4′-X-benzylidene)-1-benzosuberones (3). In order to study how the geometry of the cyclic chalcone analogues affects the transmission of substituent effects similar investigations with the respective chalcones (4) were also performed. The results obtained earlier with the five-membered analogue E-2-(4′-X-benzylidene)-1-indanones (1) were also involved in the comparisons. Geometry optimization of the unsubstituted 1a, 2a, 3a a…

Antioxidative succinobucol–sterol conjugates: Crystal structures and pseudosymmetry in the crystals

Abstract An extensive study to attach succinobucol to sterols has provided conjugates which comprise two pharmaceutically important compounds into one entity where the components are expected to have a synergistic effect. The motivation to design these novel conjugates was the need to broaden the armamentarium of current agents used in the treatment of atherosclerotic diseases and type 2 diabetes. In desire for detailed information of these compounds in solid state, which also have an influence to their physiological activity, systematic crystallization experiments were performed and as a result, X-ray quality single crystals were obtained from four succinobucol–sterol conjugates. All of th…

NMR Spectra of Some Chlorinated Diphenyliodonium Salts and Iodobenzenes

Chlorodicyclopentadienyloxoniobium(V) complexes revisited: The origin of the asymmetry in the 1H- and 13C-NMR spectra, X-ray crystal structures and ab initio/HF and DFT/B3LYP calculations

Abstract 1H- and 13C-NMR spectra of chlorodicyclopentadienyloxoniobium(V) complex I and its four 1,1′-dialkyl substituted derivatives II–V have been recorded and assigned based on DQF 1H,1H-COSY and PFG 1H,13C-HMQC and HMBC experiments. Non-equivalences of all cyclopentadienyl protons and carbons in II–V (as reflected by their different 1H- and 13C-NMR chemical shifts) are explained by synchronous and out-of-phase rotations of the substituted cyclopentadienyl rings. A non-equivalence of the methyls in III (1,1′-di-isopropyl) is explained by a detailed inspection of the rotamers of the isopropyl groups. The X-ray structural data show that III and IV (1-methyl-1′-tert-butyl) crystallize in th…

ChemInform Abstract: Ortho-Substituent Effects in N-Arylacetamides. NMR and Molecular Mechanics Investigation.

1H, 13C, 15N and 17O NMR spectra of N-phenylacetamide (acetanilide) and 21 ortho-substituted acetanilides were measured and assigned. The observed NMR parameters are related to the Hammett substituent parameters and conformational characteristics of the acetamido moiety estimated by molecular mechanics calculations. Significant relationships were found for the 13C NMR chemical shifts of C-5 (para to substituent) and the direct spin–spin coupling constant, 1J(C, H), of C-3 (ortho to substituent) with Hammett substituent parameters. For 15N NMR chemical shifts of the amido nitrogen, no general correlation with the Hammett substituent parameters was found. The interactions between functionalit…

1H,13C and15N NMR spectroscopic, x-ray structural andab initio/HF studies on nitramino andN-alkylamino-4-nitro derivatives of pyridineN-oxides and pyridines

The 1H, 13C and 15N NMR spectra in DMSO-d6 were measured for eight nitraminopyridine N-oxides, ten 4-nitropyridine N-oxides, four 2-nitraminopyridines and five 4-nitropyridines. Their chemical shift assignments are based on PFG 1H,X (X = 13C and 15N) HMQC and HMBC experiments. The relative energies for the tautomers of two nitraminopyridine N-oxides were determined by ab initio HF/6–311G** calculations. A single-crystal x-ray structural analysis was made for 4-methyl-2-nitraminopyridine: C6H7O2N3, M = 153.15, triclinic, space group P-1 (No. 2), a = 7.0275(4), b = 6.8034(3), c = 8.6086(5) A, α = 103.620(2), β = 90.309(2), γ = 122.215(3)°, V = 334.11(3) A3, Z = 2. Copyright © 2003 John Wiley …

Complex tauto- and rotamerism of 2-(R-phenyl)-1,2,3,4-tetrahydroquinazolines

Detailed NMR spectral analysis of CDCl3 solutions of 2-(R-phenyl)-1,2,3,4-tetrahydroquinazolines reveals three or four tautomeric forms. Apart from 2-[(benzylideneamino)methyl]aniline, the other chain tautomeric forms are present only in minor quantities. In general, electron-donating substituents increase the contribution of all chain forms. Lowering the temperature of the CDCl3 solution of 2-(R-phenyl)-1,2,3,4-tetrahydroquinazolines decreases the content of the 2-[(benzylideneamino)methyl]aniline form. At the same time, the amount of the ring form increases. Opening of the tetrahydropyrimidine ring in 2-(R-phenyl)-1,2,3,4-tetrahydroquinazolines was found to be an endothermic process espec…

N 2,N 2,N 6,N 6-Tetra­kis(2,3,4,5,6-penta­fluoro­benzo­yl)pyridine-2,6-diamine

The title compound, C33H3F20N3O4, is a highly fluorinated organic imide that was isolated as an unexpected product from the reaction of 2,6-diaminopyridine with 2,3,4,5,6-pentafluorobenzoyl chloride in a 1:2 molar ratio. The molecule is located on a twofold axis and one of its symmetry-independent 2,3,4,5,6-pentafluorobenzoyl groups is disordered over two sets of sites, the occupancy of the major component being 0.773 (3). In the major component, the dihedral angle between the perfluorophenyl groups is 63.64 (10)°, and these groups form dihedral angles of 67.14 (7) and 21.1 (2)° with the pyridine core. Short intermolecular C&#821…

Multinuclear Magnetic Resonance Study of 2,4,6-Triarylpyridines, 1-Methyl-2,4,6-Triarylpyridinium, and 2,4,6-Triarylpyrylium Cations

Abstract The H, 13C, 15N, and 19F NMR spectra of 2,4,6-triarylpyridines, 1-methyl-2,4,6-triarylpyridinium and 2,4,6-triarylpyrylium perchlorates have been studied. The H NMR signals of protons 3(5) in the heteroaromatic ring are deshielded due to the polarization of C-H bonds caused by delocalization of the positive charge in pyridinium and pyrylium cations. Generally, conformational and structural variations affect the 13C NMR chemical shifts of all carbons in the heteroaromatic ring. Those of carbons 3(5) can best be related to the electron-donating or electron-accepting ability of substituents. However, both electronic character of substituents and charge of heteroatom itself are needed …

Novel one-pot synthesis of quaternary ammonium halides: new route to ionic liquids

Treatment of an amide with an alkyl or substituted alkyl halide in the presence of a weak base in a one-pot reaction leads to crystalline quaternary ammonium halides with reasonable chemical yields; some of the compounds show low melting points and a liquid range of over 50–100 °C before decomposition.

Glycosidic juvenogens: derivatives bearing alpha,beta-unsaturated ester functionalities.

Abstract A series of the protected alkyl glycosides 5a / 5b – 12a / 12b was synthesized from the parent isomeric alcohols (insect juvenile hormone bioanalogs; juvenoids), 4-[4′-(2″-hydroxycyclohexyl)methylphenoxy]-3-methyl-but-2-enoic acid ethyl ester ( 1a / 1b – 4a / 4b ; racemic structures) and ( 1a – 4a ; enantiopure structures). Cadmium carbonate was used as a promoter of this Koenigs–Knorr reaction, and the products were obtained in 82–92% yields. Deprotection of the carbohydrate functionality of 5a / 5b – 12a / 12b was carefully performed using ethanolysis in the presence of zinc acetate, due to the presence of another ester functionality in the aglycone part of the molecule of protec…

The tautomerism of nitraminopyridines

1H, 13C and 15N NMR data for nitraminopyridines are discussed in terms of tautomeric equilibria in these compounds. The favoured tautomer is determined mainly from 15N NMR spectroscopy. The chemical shift of the nitrogen atom of the nitro group in nitraminopyridines and N-nitroanilines which cannot tautomerize vary from 28·0 to 35·4 ppm in DMSO solution. 3-Nitraminopyridine and 2-nitramino-3- and -5-nitropyridines behave similarly. In the 15N NMR spectra of nitrimino-1-methyldihydropyridines, used as models, an upfield shift of that atom, different from that observed for 2-nitraminopyridine, indicates the significance of the nitrimino tautomer. In contrast, a downfield shift of the ring nit…

N-Glycosylamines of 4,6-O-ethylidene-alpha-D-glucopyranose: synthesis, characterisation and structure of CO2H, Cl and F ortho-substituted phenyl derivatives and metal ion complexes of the CO2H derivative

A saccharide based ligand suitable for metal binding (HLCOOH) has been synthesized using 4,6-O-ethylidene-alpha-D-glucopyranose (4,6-O-EGP) and anthranilic acid. A few analogous glycosylamines with chloro and fluoro ortho substitutions have also been synthesized and characterised. Complexes of HLCOOH with Na+, K+, Mg2+, Ca2+, Ba2+, Cd2+ and Hg2+ have been isolated and characterised fully. The crystal structures of 4,6-O-EGP, the chloro analogue of HLCOOH and the K+ complex of L-COOH are established. The anomeric nature, orientation of the binding core and the co-ordination aspects of K+ have been derived from these structures.

Tuning the hydrogen bonding strength in 2,6-bis(cycloalkylcarbonylamino)pyridine assemblies by variable flexibility. Association constants measured by hydrogen bonded vs. non-hydrogen bonded protons

International audience; The association of 2,6-bis(cycloalkylcarbonyloamino)pyridines with rigid and non-rigid counterparts was studied in chloroform solution by 1H NMR and computational methods. The angles within the cycloalkyl ring and rotation of these substituents determine the strength of the association via triple hydrogen-bonding. The dimerization and methyl-methyl repulsion have been addressed as mechanisms restricting heterocomplexation of diacetamide. The association constants obtained by the shift changes of hydrogen-bonded protons are in agreement with those of methine protons. This "dual shift" method was proposed as an additional verification of association constants obtained …

Novel Applications of Dynamic NMR in Organic Chemistry

Abstract This review article is oriented on NMR applications in studying various dynamic processes of organic molecules. The topic as a whole is too large to be covered exhaustively in one article or by one author. Therefore, the literature searches are limited mainly for the years 1999–2001. Further, many interesting branches joined essentially with organic chemistry such as supramolecular and organometallic chemistry are left outside this article because there exist recent reviews on these topics. Similarly, the theoretical background of dynamic NMR is not included. The nature of dynamic NMR itself is changing with the recent progress in computational possibilities to estimate the differe…

Synthesis and structural studies on Ni(II) dithiocarbamates : Exploring intramolecular Ni···H-C interactions

Abstract Five new Ni(II) dithiocarbamates with NiS4, NiS2PN and NiS2PCl coordination spheres, viz. [Ni(bupmbzdtc)2] (1), [Ni(bupmbzdtc)(PPh3)(NCS)] (2), [Ni(bupmbzdtc)(PPh3)Cl] (3), [Ni(4-dpmpzdtc)(PPh3)Cl] (4) and [Ni(pbbzbudtc)(PPh3)(NCS)] (5), where bupmbzdtc = N-butyl(p-methylbenzyl)dithiocarbamato anion, 4-dpmpzdtc = 4-(diphenylmethyl)piperazinecarbodithioato anion, pbbzbudtc = N-(p-bromobenzyl)butyl-dithiocarbamato anion and PPh3 = triphenylphosphine, were synthesized and characterized by UV, IR, NMR and single crystal X-ray diffraction methods. Spectral results suggest a square planar geometry around the Ni(II) metal center for all the synthesized complexes. Single crystal X-ray stru…

Succinobucol’s New Coat — Conjugation with Steroids to Alter Its Drug Effect and Bioavailability

Synthesis, detailed structural characterization (X-ray, NMR, MS, IR, elemental analysis), and studies of toxicity, antioxidant activity and bioavailability of unique potent anti-atherosclerotic succinobucol-steroid conjugates are reported. The conjugates consist of, on one side, the therapeutically important drug succinobucol ([4-{2,6-di-tert-butyl-4-[(1-{[3-tert-butyl-4-hydroxy-5-(propan-2-yl)phenyl]sulfanyl}ethyl)sulfanyl]phenoxy}-4-oxo-butanoic acid]) possessing an antioxidant and anti-inflammatory activity, and on the other side, plant stanol/sterols (stigmastanol, β-sitosterol and stigmasterol) possessing an ability to lower the blood cholesterol level. A cholesterol-succinobucol prodr…

4-Fluoroanilines: synthesis and decomposition

Abstract Fourteen N- and/or 2-substituted 4-fluoroanilines were prepared (the series includes N–C2-bridged compounds). Some of them were found to be thermally unstable when dissolved in chloroform. Both 19 F NMR spectra and comparison of GIAO-DFT calculated and experimental 13 C chemical shifts were used to suggest decomposition products of 4-fluoroanilines.

Substituted methyl 5β-cholan-24-oates. I—17O NMR spectral characterization

Methyl esters of four common bile acids, 3α-hydroxy-5-β-cholan-24-oic (lithocholic) acid, 3α, 7α-dihydroxy-5β-cholan-24-oic (chenodeoxycholic) acid, 3α,12α-dihydroxy-5β-cholan-24-oic (deoxycholic) acid and 3α,7α,12α-trihydroxy-5β-cholan-24-oic (cholic) acid, and 14 acetylated, trifluoroacetylated, mesylated and oxo derivatives of methyl 5β-cholan-24-oates were prepared and their 17O NMR spectra recorded. In spite of their relatively high molecular masses and the rigid molecular structure of the steroid skeleton, most of the oxygens included in these structures gave well resolved 17O NMR resonance lines at natural abundance in 0.25–0.5 M acetonitrile solutions at 75°C. In agreement with the …

13C-NMR Based Evaluation of the Electronic and Steric Interactions in Aromatic Amines

Abstract: Chemical shifts of the para carbon atoms, δ(13C-4), in a series of aromatic amines were used to calculate the Ãp, ÃR and ÃOR substituent constants for different amino groups. 1-Pyrrolidino, N,N-di-n-butylamino and N,N-diethylamino groups were found to be the most strong electron-donors. ortho-Substitution decreases the donor properties of the amino group. The amino groups in 2,6-di-i-propylaniline and N,N-2,6-tetramethylaniline have very weak electron-donor properties. The nitrogen atom in benzoquinuclidine and N,N-dimethyl-2,6-di-i-propylaniline have an electron-acceptor character. The calculated substituent constants of the amino groups studied are consistent with the s…

Design, synthesis and stimuli responsive gelation of novel stigmasterol-amino acid conjugates.

Abstract An efficient synthesis of three novel stigmasterol-amino acid (glycine, l -leucine and l -phenylalanine) conjugates as stimuli responsive gelators is reported. The gelation properties of the prepared compounds were investigated in a variety of organic as well as aqueous solvents. The most striking finding of our investigation was that the hydrochloride salts of the prepared conjugates acted as gelators, whereas the neutral conjugates were either non-gelators or formed only a weak gel in anisole. The hydrochloride salts of stigmasteryl glycinate and l -leucinate form gels in n-alcohols (n = 4–10) and in ethane-1,2-diol, and that of stigmasteryl l -phenylalaninate forms gels in aroma…

Substituent effects on the photophysical properties of fluorescent 2-benzoylmethylenequinoline difluoroboranes: A combined experimental and quantum chemical study

Abstract In this study, we demonstrate a successful synergy between theory and experiment and report on the photophysical properties of a recently synthesized series of substituted 2-benzoylmethylenequinoline difluoroboranes with a view towards the effect of substitution on their properties. In general difluoroboranes are known to have a bright fluorescence but for some analogs the properties are not fully understood. Quantum chemistry methods have been applied in order to explain a complex structure of the absorption and emission spectra and to gain an insight into the charge redistribution upon the excitation of the investigated molecules. We demonstrate that the spectra of this important…

1H-, 13C-, and 15N-NMR and ESI-TOF+ MS studies of a supramolecular complex of silver(I) and a cholaphane

A novel application of the mixed anhydride procedure for synthesising lithocholic acid piperazine diamide, an important intermediate in designing bile acid-based supramolecular host molecules, is reported. The synthesis of a thiophene-containing cholaphane with transition metal complexation ability and 1H-, 13C-, and 15N-NMR as well as ESI-TOF+ MS spectral characterisation of the ligand and its Ag(I) complex are included. The coordination of the Ag(I) ion as well as an ability of the cholaphane to recognise Ag(I) ion over alkali metal ions, especially potassium ion, is discussed. The possible medical applications are also presented.

3α,3′α-Bis(n-acetoxyphenylcarboxy)-5β-cholan-24-oic acid ethane-1,2-diol diesters (n = 2-4):13C NMR chemical shifts, variable-temperature and NOE1H NMR measurements and MO calculations of novel bile acid-based dimers

Three novel bile acid-based molecular dimers, 3α,3′α-bis(n-acetoxyphenylcarboxy)-5β-cholan-24-oic acid ethane-1,2-diol diesters (n = 2–4), 1–3, were synthesized from lithocholic acid (3α-hydroxy-5β-cholan-24-oic acid) ethane-1,2-diol diester and isomeric n-acetoxybenzoyl chlorides (n = 2–4). Their cleft type conformational preferences were suggested theoretically by PM3 molecular orbital calculations. Molecular weights determined by the matrix-assisted laser desorption/ionization time-of-flight technique and 13C NMR chemical shifts of the 1–3 are also presented. Copyright © 2000 John Wiley & Sons, Ltd.

Syntheses and structural study of bile acid amidoalcohols.

Preparation, structural and thermoanalytical characterization of fourteen N-hydroxyalkyl 5beta-cholan-24-amides have been performed in this study. The utilized techniques include liquid state and CP-MAS 13C NMR spectroscopy, thermogravimetry, differential scanning calorimetry, and also powder and single crystal X-ray crystallography. The results were discussed and compared to each other and also to previous findings on similar compounds. One pure hydrate form was obtained. Six new single crystal structures were determined, including one hydrated chloroform solvate. Decomposition temperatures were found to correlate with the side chain length, and the number of the hydroxyl groups. The spati…

Synthesis, characterisation and crystal structures of Schiff bases from the reaction of 4,6-O-ethylidene-β-D-glucopyranosylamine with substituted salicylaldehydes

Multiple chemical modifications were carried out on D-glucose to result in the corresponding Schiff bases. Such modifications performed on D-glucose not only helped in increasing the solubility of the products in nonaqueous solvents, but also restricted the anomerisation of the saccharide moiety in solution. NMR study of the products revealed the presence of the β-anomeric form of the saccharide moiety in Me2SO solution. All the compounds were characterised by analytical and spectral methods. The literature is devoid of any crystal structures of saccharide–Schiff base combinations of the type reported in this paper. The crystal structures of these molecules exhibited a tridentate, ONO bindi…

CCDC 1429013: Experimental Crystal Structure Determination

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CCDC 947893: Experimental Crystal Structure Determination

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CCDC 947892: Experimental Crystal Structure Determination

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CCDC 901286: Experimental Crystal Structure Determination

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CCDC 957915: Experimental Crystal Structure Determination

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CCDC 990215: Experimental Crystal Structure Determination

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CCDC 1007104: Experimental Crystal Structure Determination

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CCDC 1014209: Experimental Crystal Structure Determination

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CCDC 947895: Experimental Crystal Structure Determination

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CCDC 957918: Experimental Crystal Structure Determination

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CCDC 957920: Experimental Crystal Structure Determination

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CCDC 841777: Experimental Crystal Structure Determination

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CCDC 996586: Experimental Crystal Structure Determination

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CCDC 990214: Experimental Crystal Structure Determination

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CCDC 996587: Experimental Crystal Structure Determination

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CCDC 922097: Experimental Crystal Structure Determination

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CCDC 1027704: Experimental Crystal Structure Determination

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CCDC 841780: Experimental Crystal Structure Determination

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CCDC 957919: Experimental Crystal Structure Determination

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CCDC 1014211: Experimental Crystal Structure Determination

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CCDC 1422861: Experimental Crystal Structure Determination

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CCDC 957917: Experimental Crystal Structure Determination

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CCDC 957914: Experimental Crystal Structure Determination

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CCDC 996588: Experimental Crystal Structure Determination

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CCDC 1422862: Experimental Crystal Structure Determination

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CCDC 1429012: Experimental Crystal Structure Determination

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CCDC 901285: Experimental Crystal Structure Determination

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CCDC 947894: Experimental Crystal Structure Determination

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CCDC 1429016: Experimental Crystal Structure Determination

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CCDC 1027705: Experimental Crystal Structure Determination

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CCDC 922098: Experimental Crystal Structure Determination

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CCDC 1014210: Experimental Crystal Structure Determination

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CCDC 1429014: Experimental Crystal Structure Determination

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CCDC 1027703: Experimental Crystal Structure Determination

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CCDC 1422860: Experimental Crystal Structure Determination

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CCDC 957921: Experimental Crystal Structure Determination

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CCDC 957916: Experimental Crystal Structure Determination

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CCDC 1429015: Experimental Crystal Structure Determination

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CCDC 1014212: Experimental Crystal Structure Determination

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Antioxidant capacities and antioxidants of strawberry, blackberry and raspberry leaves

The total phenolic content (Folin-Ciocalteu method), free radical scavenging ability expressed as DPPH value, ferric reducing antioxidant capacity (FRAP), and oxygen radical absorbance capacity (ORAC) were determined in water extracts of leaves from Rosaceae family plants (Fragaria vesca L., Rubus fructicosus L., and Rubus idaeus L.). The antioxidant capacities of the extracts (in the order of the above mentioned methods) were 73.6-88.9%, 60.1-71.4%, 49.7-78.0% respectively, and 45.3-66.5% of that of green tea water extract. Further, the presence of 15 compounds (gallic acid, rutin, ellagic acid, caffeic acid, p-coumaric acid, quercetin, kaempferol, myricetin, quercetin-3-d-glucoside, ascor…

Synthesis of Both Ionic Species of Ammonium Dithiocarbamate Derived Cholic Acid Moieties

The reaction of 3-aminopropylamide of cholic acid with CS₂ produced a bile acid derivative of dithiocarbamic acid which further formed an ammonium salt with another molecule of 3-aminopropylamide of cholic acid. The cationic 3-ammonium propylamide of cholic acid did not react further with CS₂ and the formed salt was stable in the reaction mixture, even when excess CS₂ was used. When the reaction was carried out in the presence of aqueous sodium hydroxide, only the bile acid derivative of sodium dithiocarbamate was formed. The dithiocarbamate derivatives were characterized by ¹H- and ¹³C-NMR spectroscopy and ESI-TOF mass spectrometry. peerReviewed

2-Methyl-4-phenyl-3,4-dihydroquinazoline

The title compound, C15H14N2, was formed during the lithiation of 2-methylquinazoline with phenyllithium followed by hydrolysis of the intermediate lithium 2-methyl-4-phenyl-4H-quinazolin-3-ide. NMR spectra as well as single-crystal X-ray structural data indicate that the reaction product to have the same structure in chloroform solution as in the crystalline state. The phenyl substituent is twisted out of the plane of the 3,4-dihydroquinazoline ring system by 86.47 (7)°. In the crystal, intermolecular N-HN interactions connect the molecules into infinite chains. peerReviewed