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Molecular Compounds (molecular + compound)
Selected AbstractsHomo- and Heteroleptic Hypersilylcuprates , Valuable Reagents for the Synthesis of Molecular Compounds with a Cu,Si BondEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 18 2003Karl W. Klinkhammer Abstract Unsolvated hypersilanides MHyp [Hyp = Si(SiMe3)3] of the heavier alkali metals (MI = Na, K, Cs) react with copper tert -butoxide in toluene to yield crystalline heteroleptic cuprates [MI(toluene)][tBuOCuHyp]. These cuprates proved to be valuable sources for pure hypersilylcopper and other cuprates bearing hypersilyl ligands such as the di(hypersilyl)- cuprates MI[CuHyp2]. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Fate of 14C-acrylamide in roasted and ground coffee during storageMOLECULAR NUTRITION & FOOD RESEARCH (FORMERLY NAHRUNG/FOOD), Issue 5 2008Matthias Baum Abstract Acrylamide (AA) is formed during heating of carbohydrate rich foods in the course of the Maillard reaction. AA has been classified as probably carcinogenic to humans. Storage experiments with roasted coffee have shown that AA levels decrease depending on storage time and temperature. In the present study the fate of AA lost during storage of roasted and ground (R&G) coffee was studied, using 14C-labeled AA as radiotracer. Radiolabel was measured in coffee brew, filter residue, and volatiles. In the brew, total 14C-label decreased during storage of R&G coffee, while activity in the filter residue built up concomitantly. [2,3- 14C]-AA (14C-AA) was the only 14C-related water extractable low molecular compound in the brew detected by radio-HPLC. No formation of volatile 14C-AA-related compounds was detected during storage and coffee brewing. Close to 90% of the radiolabel in the filter residue (spent R&G coffee, spent grounds) remained firmly bound to the matrix, largely resisting extraction by aqueous ammonia, ethyl acetate, chloroform, hexane, and sequential polyenzymatic digest. Furanthiols, which are abundant as aroma components in roasted coffee, have not been found to be involved in the formation of covalent AA adducts and thus do not contribute substantially to the decrease of AA during storage. [source] Hartree,Fock exchange fitting basis sets for H to Rn ,JOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 2 2008Florian Weigend Abstract For elements H to Rn (except Lanthanides), a series of auxiliary basis sets fitting exchange and also Coulomb potentials in Hartree,Fock treatments (RI-JK-HF) is presented. A large set of small molecules representing nearly each element in all its common oxidation states was used to assess the quality of these auxiliary bases. For orbital basis sets of triple zeta valence and quadruple zeta valence quality, errors in total energies arising from the RI-JK approximation are below ,1 meV per atom in molecular compounds. Accuracy of RI-JK-approximated HF wave functions is sufficient for being used for post-HF treatments like Møller,Plesset perturbation theory, MP2. Compared to nonapproximated treatments, RI-JK-HF leads to large computational savings for quadruple zeta valence orbital bases and, in case of small to midsize systems, to significant savings for triple zeta valence bases. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2008 [source] Speciation of oxidation states of elements by capillary electrophoresisJOURNAL OF SEPARATION SCIENCE, JSS, Issue 11 2003Marek Trojanowicz Abstract Progress made in the last five years in the application of capillary electrophoresis methods to chemical speciation of elements is reported on the basis of over 100 literature references. The main trends observed include development of new on- and off-capillary derivatization methods, application of new detection methods, and especially coupling of CE separation systems to powerful atomic spectroscopy and mass spectrometry instruments with various ionization techniques, providing either a sensitive element-specific detection method or a third dimension for high performance separation. Besides numerous CZE and MEKC capillary electrophoresis methods only very few examples of CE speciation with capillary electrochromatography can be found. Concerning the chemical forms of elements determined, the new procedures developed are mostly focused on redox speciation of various oxidation states of elements, metal-bound high molecular compounds, and organometallic species. [source] Anticandidal low molecular compounds from higher plants with special reference to compounds from essential oils,MEDICINAL RESEARCH REVIEWS, Issue 2 2006A. Pauli Abstract The most active low molecular weight compounds from higher plants against Candida species are compiled from a database of antimicrobials (Amicbase) to find out new hints on their mechanism of action. The selected compounds possess strong inhibitory activities in vitro against Candida species either in the agar diffusion test, bioautography, agar dilution test, serial dilution test, or activity in the vapour phase. The test conditions are listed thoroughly and aspects of the different methods and recent developments in the testing of anticandidal drugs are discussed. The anticandidal spectra of drugs, antiseptics, and disinfectants licensed on the major markets are given for comparision of activities with compounds from natural sources. So far known mechanisms of action are described and some new structure,activity relationships are deduced from relationships between biological activities and chemical and physical parameters. Main specific targets of natural anticandidals are the ergosterol pathway, respiratory chain, and chitin biosynthesis. © 2005 Wiley Periodicals, Inc. Med Res Rev [source] | ||||||||||