Search results for "Proton NMR"
showing 10 items of 324 documents
The fluxional behaviour of η6(bicyclo[6.2.0]deca-2,4,6-triene) hexacarbonyl diruthenium (Ru-Ru) by 1H and 13C NMR techniques
1977
Abstract The variable temperature 1 H NMR spectra of [Ru 2 (CO) 6 η 6 -C 10 H 12 )] (C 10 H 12 = bicyclo [6.2.0]-deca-2,4,6-triene) shows that this molecule undergoes the fluxional behaviour previously reported for [M 2 (CO) 6 (η 6 -polyolefin)] complexes (M = Fe, Ru) which have in the solid an asymmetric skew-type structure. The use of 13 C NMR techniques, employed for the first time for a diruthenium complex of the above type, allows a comparison of the mechanism of the fluxional process with that of the diiron analog. Although the observed line shape changes of the carbonyl resonances in the two complexes are somewhat different the process are basically the same. In the case of the dirut…
Supramolecular Adducts of Ferrocene and Five Bile Acid Derived Triolides
1997
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 …
Crystal Structure and Host-Guest Binding Ability of Three Types of Pillar[5]arenes
2015
A systematic research of the structural characterization and the host-guest binding abilities between three types of pillar[5]arenes 3–5 (3 for Structure Type I, 4 for Structure Type II and 5 for Structure Type III) is carried out by 1H NMR measurements and X-ray study. The results show that the configurations or symmetry of their cavities not only have large difference in these three types of pillar[5]arenes, but also have more or less variations even in the same structure type or the same host locked different guests such as crystals of 3a–3b, 4a–4d. On the other hand, the complexation behavior of pillar[5]arenes with 1,4-dibromobutane (DBB) is affected by the different symmetrical struct…
1H-NMR studies on poly(oxyethylene)-bound oligopeptides
1983
Conformational studies on poly(oxyethylene)-bound homo-, oligo-, guest-host, and sequential peptides synthesized according to the liquid-phase method were carried out by means of 1H-nmr spectroscopy. The solubilizing effect of the C-terminal polymeric support allowed a thorough investigation of the secondary structure in solution.
Sterically crowded triazenides as novel ancillary ligands in copper chemistry
2011
Abstract We have synthesized copper salts MN3RR′ derived from the biphenyl- or m-terphenyl-substituted triazenes Tph2N3H (1a) and Dmp(Tph)N3H (1b) (Dmp = 2,6-Mes2C6H3 with Mes = 2,4,6-Me3C6H2; Tph = 2-TripC6H4 with Trip = 2,4,6-i-Pr3C6H2). The homoleptic copper triazenide [CuN3Tph2] (2a) was obtained in high yield from the metallation of 1a with mesityl copper in n-heptane, while the complex [CuN3(Dmp)Tph] (2b) was generated by the same method in situ only. Reaction of 2a with triphenylphosphane gave the 2:1 adduct [CuN3Tph2(PPh3)2] (3a), regardless of the used complex/donor ratio, while reaction of 2a or 2b with a stochiometric amount of t-butylisonitrile afforded the 1:1 adducts [Tph2N3Cu…
1H, 13C and 15N NMR spectral characterization of twenty-seven 1,2-diaryl-(4E)-arylidene-2-imidazolin-5-ones.
2006
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.
Complete 1H and 13C NMR assignments of clerodane diterpenoids of Salvia splendens.
2006
Unambiguous and complete assignments of 1H and 13C NMR chemical shifts for five clerodane diterpenes, four of them isolated from Salvia splendens (salviarin, splendidin and splenolides A and B) and one obtained by acetylation of splenolide A, are presented. The assignments are based on 2D shift-correlated [1H,1H–COSY, 1H,13C-gHSQC–1J(C,H) and 1H,13C-gHMBC-nJ(C,H) (n = 2 and 3)] and nuclear Overhauser effect (NOE) experiments. The conformation of the rings of these compounds is supported by the 3J(H,H) values and NOE results. Copyright © 2006 John Wiley & Sons, Ltd.
Surface Relaxivity of Cement Hydrates
2014
Numerous aspects of the physical chemistry of colloidal systems are conditioned by the solid–liquid interface, and this is also the case for hydrated cement systems. Estimating the surface area is thus essential for studying the kinetics of cement hydration and admixture adsorption. Proton nuclear magnetic resonance (NMR) relaxation techniques have already proven useful for this objective, but, for hydrating cements at early ages, it is necessary to know the surface relaxivities of all of the individual phases present to correctly interpret the relaxation data. This paper reports the results of a comparison of NMR relaxometry and Brunauer–Emmett–Teller gas adsorption measurements on various…
Comparative NMR and IR spectral, X-ray structural and theoretical studies of eight 6-arylidenedibenzo[b,e]thiepin-11-one-5,5-dioxides
2007
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.
Synthesis and antimicrobial screening of tetra Schiff bases of 1,2,4,5-tetra (5-amino-1,3,4-thiadiazole-2-yl)benzene
2014
Abstract In the present study, novel tetra Schiff bases were synthesized by condensation of 1,2,4,5-tetra (5-amino-1,3,4-thiadiazole-2-yl)benzene with different aromatic aldehydes. The chemical structures were confirmed by means of IR, 1 H NMR, 13 C NMR, and elemental analysis. All compounds were screened for antibacterial ( Staphylococcus aureus ATCC-9144, Staphylococcus epidermidis ATCC-155, Micrococcus luteus ATCC-4698, Bacillus cereus ATCC-11778, Escherichia coli ATCC-25922, and Pseudomonas aeruginosa ATCC-2853) and antifungal ( Aspergillus niger ATCC-9029 and Aspergillus fumigatus ATCC-46645) activities by paper disc diffusion technique. The minimum inhibitory concentrations (MICs) of …