Search results for "MOLECULE"
showing 10 items of 5162 documents
2D Bimetallic Oxalate‐Based Ferromagnets with Inserted [Fe(4‐Br‐sal 2 ‐trien)] + and [Fe(3‐R‐sal 2 ‐trien)] + (R = Br, Cl and CH 3 O) Fe III Spin‐Cro…
2012
The syntheses, structures and magnetic properties of the compounds of formula [FeIII(4-Br-sal2-trien)][MnIICrIII(ox)3]0.67Cl0.33·CH3OH_solvate (1), [FeIII(3-Br-sal2-trien)][MnIICrIII(ox)3]·(CH3CN)2 (2), [FeIII(3-Cl-sal2-trien)][MnIICrIII(ox)3]·(CH3OH)2·(CH3CN)2 (3) and [FeIII(3-CH3O-sal2-trien)][MnIICrIII(ox)3]·(CH3OH)·(H2O)1.5·(CH2Cl2)0.5 (4) are reported. The four structures present a 2D honeycomb anionic layer formed by MnII and CrIII ions linked through oxalate ligands and a cationic layer of the FeIII complexes intercalated between the 2D oxalate network. The main differences compared with previous 2D oxalate-based structures are the presence of double layers of cations in compounds 1,…
Spectroscopic studies and crystal structure of bis(N-2-pyridinylcarbonyl-2-pyridinecarboximidato) manganese(II) monohydrate: Zero-field splitting par…
1990
Abstract The X-ray crystal structure of bis(N-2-pyridinylcarbonyl-2-pyridinecarboximidato)manganese(II) monohydrate, Mn(BPCA)2·H2O, has been determine
Progress in Understanding of the Interactions between Functionalized Polyolefins and Organo-Layered Double Hydroxides
2013
The dispersion of organo-layered double hydroxides (O-LDH) in functionalized polyolefins (POs) is investigated. Two different polyethylene matrices (maleic anhydride (MAH) and diethyl maleate functionalized) are tested and a hydrogenated fatty acid modified LDH is used. The attention is focused on evidencing the interaction between the functional groups of the polymer and the O-LDH through FT-IR. Moreover, a combination of solvent fractionation, morphological, and rheological characterizations enables to gain a deeper insight into the structure of these composites. In particular, the formation of bridging bonds between the particles and MAH functionalized macromolecules is assumed, possibly…
Competing salt effects on phase behavior of protein solutions: tailoring of protein interaction by the binding of multivalent ions and charge screeni…
2014
The phase behavior of protein solutions is affected by additives such as crowder molecules or salts. In particular, upon addition of multivalent counterions, a reentrant condensation can occur; i.e., protein solutions are stable for low and high multivalent ion concentrations but aggregating at intermediate salt concentrations. The addition of monovalent ions shifts the phase boundaries to higher multivalent ion concentrations. This effect is found to be reflected in the protein interactions, as accessed via small-angle X-ray scattering. Two simulation schemes (a Monte Carlo sampling of the counterion binding configurations using the detailed protein structure and an analytical coarse-grain…
A Polar18F-Labeled Amino Acid Derivative for Click Labeling of Biomolecules
2014
This work describes the synthesis and 18F-labeling of an amino acid based prosthetic group that is able to participate in copper(I)-catalyzed cycloadditions. The prosthetic group can be used for 18F labeling of biomolecules under mild conditions. The synthesis started with L-serine methyl ester, which was derivatized by introducing an alkyne moiety and a leaving group for 18F labeling. Subsequently, 18F labeling as well as deprotection conditions were screened, which resulted in an overall radiochemical yield (RCY) of around 28 %. Furthermore, the 18F-labeled prosthetic group was treated with an azido cyclic Arg-Gly-Asp (cRGD) peptide as a model system in very high RCY of 98 %.
Unexpected formation of chroman-4-ones during the synthesis of 4-hydroxymethyl-2H-chromenes from 4-aryloxybut-2-yn-1-ols
1986
Abstract The unexpected formation of chroman-4-ones by refluxing 4-aryloxybut-2-yn-1-ols in diethylaniline has been studied, 4-hydroxymethyl-2H-chromene and chroman-4-carboxaldehyde derivatives being established as intennediates.
Cyclocondensation reaction of 1,2-diamino-4-methylbenzene andp-substituted acetophenones
1993
1,2-Diamino-4-methylbenzene 1 reacts in the presence of sulphuric acid with 4-substituted acetophenones 2a-e yielding 2,4-diaryl-2,3-dihydro-2,8-dimethyl-1H-1,5-benzodiazepines 3a-e and as minor component 2,4-diaryl-2,3-dihydro-2,7-dimethyl-1H-1,5-benzodiazepines 4a-e. The ratio 3:4 is in the range of 7:3. The structure determination of the regioisomers was performed by NOE measurements.
Synthesis and pharmacological evaluation of enantiomerically pure endo-configured KOR agonists with 2-azabicyclo[3.2.1]octane scaffold
2021
Conformationally restricted bicyclic KOR agonists 10 with an endo configured amino moiety were synthesized to analyze the bioactive conformation of conformationally flexible KOR agonists such as 2-5. A seven-step, chiral pool synthesis starting with (S)-configured 4-oxopiperidine-2-carboxylate 13 was developed. cis and trans configured diesters 12 were obtained in a 3:1 ratio via hydrogenation of the α,β unsaturated ester 14. After establishment of the bicyclic scaffold, a diastereoselective reductive amination of ketone 11 provided exclusively the endo configured bicyclic amines 10a,b. The 3:1 mixtures of enantiomers were separated by chiral HPLC, respectively, leading to enantiomerically …
Chemoenzymatische „Chiral-Pool”-Synthese von (+)-exo-Brevicomin aus Kohlenhydraten mit Fructose-1,6-diphosphat-Aldolase
1990
Chemoenzymatic “Chiral-Pool” Synthesis of (+)-exo-Brevicomin from Carbohydrates Using Fructose 1,6-Diphosphate Aldolase Fructose-1,6-diphosphate aldolase (EC 4.1.2.13) catalyzes the stereospecific aldol reaction between 1,3-dihydroxyacetone phosphate (4) and 5-oxohexanal (3) or its 5-dithiane-protected analog 8. The products of the aldol reactions are dephosphorylated with acid phosphatase (EC 3.1.3.2). Whereas the aldol adduct of 3 cyclizes spontaneously to give the bicyclic brevicomin precursor 3, the adduct of 8 first has to be deprotected with sulfuryl chloride and wet silica gel. The resulting bicyclic α-hydroxy ketone 3 is reduced with LiAlH4 to form the 1,2-diol 14 which is then deox…
Double Diastereoselection in Aldol Reactions Mediated by Dicyclohexylchloroborane between Chiral Aldehydes and a Chiral Ethyl Ketone Derived from l-E…
2005
Both matched and mismatched diastereoselections have been observed in the aldol reactions of a range of chiral aldehydes with the dicyclohexylboron enolate of a chiral ethyl ketone related to l-erythrulose. As was previously observed in the corresponding aldol reactions with l-erythrulose derivatives, the Felkin−Anh model provides an adequate explanation for the stereochemical outcome of reactions with chiral α-methyl aldehydes. However, a satisfactory account of the results observed with α-oxygenated aldehydes was only possible with the Cornforth model. As a practical application of the methodology described herein, a C1−C9 fragment of the structure of the antifungal macrolide soraphen A1α…