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991.
D.J. Walton S.S. Phull D. Colton P. Richards A. Chyla T. Javed L. Clarke J.P. Lorimer T.J. Mason 《Ultrasonics sonochemistry》1994,1(1)
This paper describes the previously unreported electrogenerated chemiluminescence (ECL) from the electro-oxidation of several aryl carboxylates at a platinum flag electrode in aqueous, methanolic and acetonitrile solutions using tetramethylammonium hydroxides as a supporting electrolyte. In most cases electrochemiluminescence was markedly enhanced by simultaneous irradiation with ultrasound during electrolysis. Increase in electrochemiluminescence intensity with electrolysis current and carboxylate concentration was observed. Addition of a radical scavenger or purging of the solution with oxygen lowers ECL emission intensity. In contrast the presence of oxygen enhances the intensity of sonoluminescence, which is a concurrent but weaker process occurring under ultrasonic irradiation alone. Ring-substituted phenylacetates almost always produced less electrochemiluminescence than the unsubstituted parent molecule, though within the substituents studied chloro-substituted phenylacetates produced more ECL intensity than either methoxy- or nitro-substituted derivatives. 相似文献
992.
993.
994.
Marcel Gielen Edward R. T. Tiekink Abdeslam Bouhdid Dick de Vos Monique Biesemans Ingrid Verbruggen Rudolph Willem 《应用有机金属化学》1995,9(7):639-648
Crystal structure determinations of {[(F5C6COO)Bu2Sn]2O}2 and {[(4-F-C6H4COO)-Bu2Sn]2O}2 show that the structures are similar and feature central Bu4Sn2O2 units with two Bu2Sn groups connected by bridging oxygen atoms. Each pair of exo- and endo-cyclic tin atoms is linked by an almost symmetrically bridging carboxylate group, with the two remaining groups attached to the exocyclic tin atom only. Crystals of {[(F5C6COO)Bu2Sn]2O}2 are triclinic, space group P1, with unit cell dimensions a = 12.425(3) Å, b = 13.090(5) Å, c = 11.697(3) Å, α = 95.31(3)°, β = 93.28(2)°, γ = 113.01(2)°, V = 1734(1) Å3, Z = 1. Crystals of {[(4-F-C6H4COO)Bu2Sn]2O}2, are also triclinic, space group PI, a = 12.599(6) Å, b= 25.359(4) Å, c = 11.480(4) Å, α = 91.44(3)°, β = 114.77(3)°, γ=97.43(3)°, V=3289(2) Å3, Z=2. The structures were refined to final R= 0.046, Rw = 0.046 for 4312 reflections with I≥ 3.0 σ(l) for {[(F5C6COO)Bu2Sn]2O}2 and R=0.061, Rw=0.068 for 4112 reflections with l≥3.0 σ(l for {[(4-F-C6H4COO)Bu2Sn]2O}2. 相似文献
995.
The dinuclear molecule of [(Me3SiCH2)Cl2Sn]2(CH2)3 adopts an extended conformation and features distorted tetrahedral tin centres, with the greatest distortion manifested in the C? Sn? C angles of approximately 128 °. The distortions are ascribed to the influence of intermolecular Sn···Cl interactions. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
996.
A. Chakrabarti Sk. Kamruddin T. K. Chattopadhyaya A. Roy B. N. Chakraborty K. C. Molloy E. R. T. Tiekink 《应用有机金属化学》1995,9(4):357-364
The preparation and spectroscopic characterization of [R3Sn(O2CCH2SC5H4N-4)], R == Ph, benzyl (Bz), cyclohexyl (c-Hex) and n-Bu, and of [R3Sn(O2CCH2SC4H3N2-2,6)], R == Me, Ph and n-Bu, are reported. The 2-pyrimidyl compounds feature trigonal bipyramidal tin centres with trans-R3SnO2 geometries as was confirmed by X-ray crystallography for [Ph3Sn(O2CCH2SC4H3N2-2,6)]. ¶ By contrast the 4-pyridyl compounds have trigonal bipyramidal geometries in the solid state (arising from intermolecular Sn…N interaction) and tetrahedral geometries in solution. The biocidal activity of these compounds against the fungi Helminthosporium maydis (ITCC 2675) and H. oryzae (ITCC 2675), both of which damage crops such as maize and rice, shows promise. Encouraging is the observation that the compounds show no adverse phytotoxicity at concentrations to 10?3M. 相似文献
997.
998.
High-performance liquid chromatography coupled with graphite furnace atomic absorption spectroscopy (HPLC? GF AA) gives element-specific detection of environmental samples containing trace amounts of organotin or organolead species. The direct GF AA of organotin and organolead species is subject to errors arising primarily from loss of analyte prior to atomization, probably through the formation of refractory carbides and of compounds or complexes that are volatile at low temperatures. Examples abound in the literature of signal suppression in the GF AA of organometallic species in environmental samples, and several furnace tube modifications have been developed to overcome this suppression. Here, the analyte and a modifier are co-pipetted into a conventional furnace tube, from either a solution of analyte or an HPLC effluent. Oxides of transition metals (e.g. chromium, manganese, or tungsten) are shown to enhance both tin and lead signals, whereas chlorides do not, suggesting the low-temperature formation of relatively involatile metal oxides or volatile metal chlorides, respectively. In the absence of modifier, GF AA signal intensities decrease consecutively for equal quantities of mono-, di-, tri- and tetra-butyltin species, but are nearly equal for the first three in the presence of complexing dichromate (Cr2O72?). The lesser signal increase for tetrabutyltin indicates a dissimilar low-temperature complexation chemistry for the fully ligated neutral organometal to that for the ligated ions. similar results are demonstrated in post-column addition of a matrix modifier to effluent containing either organotin or organolead species. 相似文献
999.
1000.
本文简要介绍磷、硫、砷、硅、硼和锡有机化合物在有机合成应用中研究得较活跃的一些例子,并着重讨论应用元素有机化合物合成立体专一性、光学活性和生理活性的化合物。 相似文献