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11.
D A Richards 《Journal of chromatography. A》1979,175(2):293-299
Electrochemical detection of tryptophan metabolites following separation on a reversed-phase high-performance liquid chromatography column was compared with other means of detection. Of 29 compounds studied, 26 could be detected at a sensitivity comparable to that of fluorescence derivatisation procedures. Response was linear over a wide range of concentrations and selectivity was shown to be superior to ultraviolet detection when analysing urine. Additionally, it was possible to control selectivity so that only those tryptophan metabolites from the tryptophan hydroxylase pathway were detected. This is of particular value in the study of distrubances of serotonin metabolism and is unique to this type of detector. 相似文献
12.
Hogarth G Holman KT Pateman A Sella A Steed JW Richards I 《Dalton transactions (Cambridge, England : 2003)》2005,(16):2688-2695
The iodine(III) reagent, PhI[double bond, length as m-dash]NTs, acts as a source of the nitrene fragment NTs, which undergoes facile insertion into the metal-sulfur bonds of a range of dithiocarbamate complexes. Addition of two equivalents of PhI=NTs to [M(S(2)CNR2)2] affords sulfido-amido complexes [M{SC(NR2)SNTs}2](M=Ni, Cu), which insert two further nitrene fragments to afford zwitterionic tetraamido complexes [M{TsNSC(NR2)SNTs}2](M=Co, Ni, Cu). Crystallographic studies have been carried out on both types of complex allowing possible resonance hydrids of the new ligand types to be assessed. 相似文献
13.
Addition of palladium acetate to 2-(dicyclohexylphosphino)-phenylferrocene gave palladacycle 16 that is a very effective precatalyst for the Suzuki cross-coupling of aryl chlorides at room temperature (1 mol% 16) or 60 degrees C (> or = 0.01 mol% 16). 相似文献
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15.
Stewart N. Anderson David L. Hughes Raymond L. Richards 《Transition Metal Chemistry》1985,10(1):29-30
Summary The compoundtrans-[MoCl2(PMe2Ph)4] has been prepared by the reduction of MoCl5 (by Mg) or of [MoCl3(PMe2Ph)3] (by LiBun) in the presence of PMe2Ph in tetrahydrofuran (THF). It has eff=2.84 B.M. and crystallises in space group P1 witha=11.591(3),b=12.931(3),c=12.703(3) Å, = 95.28(2), =105.97(2), =103.54(2)°. Refinement of the structure gave R=0.036. The Mo-Cl and Mo-P distances average 2.443(6) and 2.534(8) Å, respectively.Low-valent phosphine complexes of the Group VI metals continue to attract much attention because of their involvement in studies of the catalytic activation of dinitrogen(1), dihydrogen(2, 3), alkenes and alkynes(4). As a by-product during our studies of dinitrogen(1) and hydride(2) complexes of molybdenum and tungsten, we obtainedtrans-[MoCl2- (PMe2Ph)4] as yellow, paramagnetic crystals (eff= 2.84 B.M.). We first obtained the compound during the attempted synthesis ofcis-[Mo(N2)2(PMe2Ph)4] by reduction of MoCl5 with Mg in the presence of PMe2Ph (see Experimental). Upon identification of the compound we found that it could be readily synthesised by treatment of [MoCl3(PMe2Ph)3](5) with LiBun in THF in the presence of PMe2Ph (experimental).The complex was shown to have thetrans structure by x-ray analysis (Figure). Analogues oftrans-[MoCl2(PMe2Ph)4] have been prepared, namely [CrCl2(Me2PCH2CH2PMe2)2](6),trans- [MoCl2(PMe3)4](7), [WCl2(PMe2Ph)4](8) and [WCl2(PMe3)4](4), of which onlytrans-[MoCl2(PMe3)4] has been examined by X-rays(7). Its principal structural parametersi.e. d(Mo-Cl)= 2.420(6), d(Mo-P)av=2.496(3) Å(6) are close to those found here fortrans-[MoCl2(PMe2Ph)4]. 相似文献
16.
Evidence is given that, when solutions of diene monomers and anthracene in tetrahydrofuran are reacted with alkali metal and subsequently titrated with linking agents such as alkyl dihalides, copolymers are formed; they contain the 9,10-dihydroanthracene adduct and the diene in the same proportion as in the original solution. The structures of these copolymers have been elucidated by NMR spectroscopy and the mechanism of formation is discussed. 相似文献
17.
M P Richards 《Journal of chromatography. A》1989,482(1):87-97
Reversed-phase high-performance liquid chromatography (RP-HPLC) was used to separate metallothionein (MT) isoforms and on-line atomic absorption spectrophotometric (AAS) detection was used to quantitatively determine their metal content. With this coupled system (HPLC-AAS), it was possible to determine the zinc, cadmium and copper content of individual horse kidney MT isoforms. When rabbit liver MT and the purified isoforms (MT-1 and MT-2) were subjected to RP-HPLC and the zinc-containing peaks of the MT sample to MT-1 or MT-2. HPLC-AAS was used to identify zinc-induced MT in heat-treated cytosol from turkey hen liver, thereby demonstrating its application to the analysis of crude tissue extracts. A standard curve was established using turkey liver MT for the quantitative determination of the zinc content of MT isoforms. There was excellent linear correlation between the micrograms of zinc bound to MT injected onto the column (ranging from 0.34 to 3.43 micrograms of MT-bond zinc) and the integrated peak area of the atomic absorbance for zinc. Using this standard curve, it was possible to quantitate the amount of MT-bound zinc in cytosol extracts of cultured turkey embryo hepatocytes exposed to varying levels of supplemental zinc in the culture medium. 相似文献
18.
P.A. Bates E.J. Ditzel M.P. Hartshorn Huong Tuong Ing K.E. Richards W.T. Robinson 《Tetrahedron letters》1981,22(24):2325-2328
Dinitration of 2,4,5-tribromo-3,6-dimethylphenol(1) gives either the tribromodinitro-compound(2) or its acyloin rearrangement product(3), depending on the reaction conditions: X-ray crystal structure analyses are reported for compounds (2) and (3). 相似文献
19.
20.
An experimental thermal pulse combustor and a differential equation model of this device are shown to exhibit chaotic behavior under certain conditions. Chaos arises in the model by means of a progression of period-doubling bifurcations that occur when operating parameters such as combustor wall temperature or air/fuel flow are adjusted to push the system toward flameout. Bifurcation sequences have not yet been reproduced experimentally, but similarities are demonstrated between the dynamic features of pressure fluctuations in the model and experiment. Correlation dimension, Kolmogorov entropy, and projections of reconstructed attractors using chaotic time series analysis are demonstrated to be useful in classifying dynamical behavior of the experimental combustor and for comparison of test data to the model results. Ways to improve the model are suggested. (c) 1995 American Institute of Physics. 相似文献