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21.
Françoise Arnaud-Neu Suzanne Cremin Des Cunningham Stephen J. Harris Patrick McArdle M. Anthony McKervey Maureen McManus Marie-José Schwing-Weill K. Ziat 《Journal of inclusion phenomena and macrocyclic chemistry》1991,10(3):329-339
Treatment ofp-t-butyltetrahomodioxacalix[4]arene with ethyl bromoacetate yields a tetraester derivative (4) whose crystal and molecular structure have been determined and whose ion binding properties have been assessed by phase transfer and stability constant measurements. Colorless transparent triclinic crystals (obtained from methoxyethanol) C62H84O14,a = 10.347(2),b = 11.583(2),c = 13.448(3) Å, = 72.04(2), = 86.50(2)°, = 81.23(2)°, space group
,Z = 1, MoK
radiation = 0.70930 Å. Refinement was carried out using 2221 reflections withI > 1.5(I). The complexation properties resemble those of calix[6]arene hexaester (6), although weaker, with a preference for the larger alkali cations. Ca2+ and Ba2+; though not extracted, are more strongly complexed than alkali cations. Eu3+ is better complexed than Na+.Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82106 (22 pages) and at the Cambridge Crystallographic Data Centre, University Chemical Laboratory, Lensfield Road, Cambridge CB2 9EW, U.K. 相似文献
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The first examples of the application of phase transfer catalysis to orthometalation are described. 相似文献
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The kinetics of the stoichiometric phase-transfer carbonylation of benzyl bromide by the cobalt carbonyl anion have been investigated. Pseudo first order constants vary linearly with the amount of tetrabutylammonium chloride present. The effect of the solvent is partly due to its ability to extract the ion pair Bu4N+Co(CO)4? into the organic phase. This ion pair is barely soluble in water and the amount of Co(CO)4? anion in the organic phase is kept constant by a simple anion exchange mechanism without migration of the tetrabutylammonium cation. 相似文献
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Basha MT Chartres JD Pantarat N Ali MA Mirza AH Kalinowski DS Richardson DR Bernhardt PV 《Dalton transactions (Cambridge, England : 2003)》2012,41(21):6536-6548
The iron coordination and biological chemistry of a series of heterocyclic dithiocarbazate Schiff base ligands is reported with regard to their activity as Fe chelators for the treatment of Fe overload and also cancer. The ligands are analogous to tridentate heterocyclic hydrazone and thiosemicarbazone chelators we have studied previously which bear NNO and NNS donor sets. The dithiocarbazate Schiff base ligands in this work also are NNS chelators and form stable low spin ferric and ferrous complexes and both have been isolated. In addition an unusual hydroxylated ligand derivative has been identified via an Fe-induced oxidation reaction. X-ray crystallographic and spectroscopic characterisation of these complexes has been carried out and also the electrochemical properties have been investigated. All Fe complexes exhibit totally reversible Fe(III/II) couples in mixed aqueous solvents at potentials higher than found in analogous thiosemicarbazone Fe complexes. The ability of the dithiocarbazate Schiff base ligands to mobilise Fe from cells and also to prevent Fe uptake from transferrin was examined and all ligands were effective in chelating intracellular Fe relative to known controls such as the clinically important Fe chelator desferrioxamine. The Schiff base ligands derived from 2-pyridinecarbaldehyde were non-toxic to SK-N-MC neuroepithelioma (cancer) cells but those derived from the ketones 2-acetylpyridine and di-2-pyridyl ketone exhibited significant antiproliferative activity. 相似文献
25.
Ján Stariat Petra Kovaříková Jiří Klimeš Danuta S. Kalinowski Des R. Richardson 《Analytical and bioanalytical chemistry》2010,397(1):161-171
This study was focused on a liquid chromatography/tandem mass spectrometry (LC/MS/MS) method development for quantification
of a novel potential anticancer agent, 2-benzoylpyridine 4-ethyl-3-thiosemicarbazone (Bp4eT), in aqueous media. Solid Bp4eT
was found to consist predominantly of the Z isomer, while in aqueous media, both isomers coexist. Sufficient separation of both isomers was achieved on a Synergi 4u
Polar RP column with a mobile phase composed of 2 mM ammonium formate, acetonitrile, and methanol (30:63:7; v/v/v). The photo diode array analysis of both isomers demonstrated different absorption spectra which hindered UV-based quantification.
However, an equal and reproducible response was found for both isomers using an MS detector, which enables the determination
of the total content of Bp4eT (i.e., both E− and Z− isomeric forms) by summation of the peak areas of both isomers. 2-Hydroxy-1-naphthylaldehyde 4-methyl-3-thiosemicarbazone
(N4mT) was selected as the internal standard. Quantification was performed in selective reaction monitoring using the main
fragments of [M+H]+ (240 m/z for Bp4eT and 229 m/z for N4mT). The method was validated over 20–600 ng/ml. This procedure was applied to a preformulation study to determine
the proper vehicle for parenteral administration. It was found that Bp4eT was poorly soluble in aqueous media. However, the
solubility can be effectively improved using pharmaceutical cosolvents. In fact, a 1:1 mixture of PEG 300/0.14 M saline markedly
increased solubility and may be a useful drug formulation for intravenous administration. This investigation further accelerates
development of novel anticancer thiosemicarbazones. The described methods will be useful for analogs currently under development
and suffering the same analytical issue. 相似文献
26.
The asymmetric synthesis of both enantiomers of cis-lauthisan (3) is achieved in only six steps from diethyl pimelate (4), the key steps being the diastereodivergent reduction of beta-ketosulfoxide 7 and the highly cis-stereoselective Et(3)SiH/TMSOTf-promoted reductive cyclization of enantiopure hydroxy sulfinyl ketones (S)-14 and (R)-14. 相似文献
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Multi-dimensional spherically symmetric spacetimes are of interest in the study of higher-dimensional black holes (and solitons) and higher-dimensional cosmological models. In this paper we shall present a comprehensive investigation of solutions of the five-dimensional spherically symmetric vacuum Einstein field equations subject only to the condition of separability in the radial coordinate (but not necessarily in the remaining two coordinates). A variety of new solutions are found which generalize a number of previous results. The properties of these solutions are discussed with particular attention being paid to their possible astrophysical and cosmological applications. In addition, the four-dimensional properties of matter can be regarded as geometrical in origin by a reduction of the five-dimensional vacuum field equations to Einstein's four-dimensional theory with a non-zero energy-momentum tensor constituting the material source; we shall also be interested in the induced matter associated with the new five-dimensional solutions obtained. 相似文献
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