Their Properties (their + property)

Distribution by Scientific Domains

Selected Abstracts

Synthesis of Some Trifluoromethylated Cyclodextrin Derivatives and Analysis of Their Properties as Artificial Glycosidases and Oxidases

Jeannette Bjerre
Abstract Cyclodextrin derivatives containing trifluoromethyl groups at C6 of the A and D rings were synthesized for the purpose of creating artificial enzymes. The compounds were synthesized by perbenzylation of ,-cyclodextrin followed by selective A,D-debenzylation according to Sina˙. Subsequent oxidation to dialdehyde with Dess,Martin periodinane followed by addition of CF3 by using Arduengo carbene and TMSCF3 led to the C6 -bistrifluoromethylated alcohols. These were either deprotected by hydrogenolysis or subjected to another round of oxidation to provide the corresponding ketones that were deprotected. The trifluoromethylated alcohols were found to be weak artificial enzymes catalysing hydrolysis of nitrophenyl glycosides at neutral pH with a kcat/kuncat of up to 56. It is proposed that this catalysis is analogues to the catalysis performed by related cyanohydrins. The trifluoro ketones were likewise weak articial enzymes catalysing oxidation of amines to nitro derivatives or alcohols to ketones with a kcat/kuncat of up to 133. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

4,4-Dialkyl-Substituted N-Methylmorpholinium 3,5-Dicyano-6-oxo-1,4,5,6-tetrahydropyridine-2-thiolates and Some of Their Properties.

CHEMINFORM, Issue 20 2004
V. D. Dyachenko
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

Barium Ferrite Powders Prepared by Microwave-Induced Combustion Process and Some of Their Properties.

CHEMINFORM, Issue 13 2004
Yen-Pei Fu
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

Benzo[b]phosphole-Containing ,-Electron Systems: Synthesis Based on an Intramolecular trans -Halophosphanylation and Some Insights into Their Properties

Aiko Fukazawa Dr.
Abstract The intramolecular trans -halophosphanylation of 2-(aminophosphanyl)phenylacetylenes mediated by PBr3 followed by the oxidation with H2O2, produces 3-bromobenzo[b]phosphole oxide derivatives. This cyclization is also used for the synthesis of a 3-iodo derivative by conducting the reaction in the presence of LiI. Based on this synthetic method, various benzophosphole-containing ,-conjugated compounds, including a phosphoryl and methylene-bridged stilbene 10, 2,3,6,7-tetraphenylbenzo[1,2- b:4,5- b,]diphosphole- P,P, -dioxides 11, and their phosphine sulfide derivatives 12, are synthesized. The study of the structure,property relationships in a series of the bridged stilbenes, including a bis(methylene)-bridged stilbene 10, and a bis(phosphoryl)-bridged stilbene, reveals that as the contribution of the phosphoryl groups increased, the absorption and emission maxima substantially shift to longer wavelengths. The intrinsic substituent effects of the phosphoryl group in this skeleton are to decrease the oscillator strength of the electronic transition and thus decrease the radiative decay rate constants from the singlet excited state. Nevertheless, these compounds maintain high fluorescence quantum yields (,F>0.8) owing to the significantly retarded nonradiative decay process. In the study of the benzodiphosphole derivatives 11 and 12, their cyclic voltammetry revealed that both of the phosphoryl and phosphine sulfide derivatives have low reduction potentials (,1.7 to ,1.8,V vs ferrocene/ferrocenium couple) with the high reversibility of the redox waves. These compounds also showed high thermal stabilities with the high glass transition temperatures of 147,159,°C, indicative of their potential utilities as amorphous materials. [source]