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51.
L. A. Shundrin I. G. Irtegova A. D. Rogachev V. A. Reznikov 《Russian Chemical Bulletin》2005,54(5):1178-1184
The electrochemical reduction of 3,3′-bi(2-R-5,5-dimethyl-4-oxopyrrolinylidene) 1,1′-dioxides (R = CF3, Me, Ph, But), which are cyclic dinitrons with conjugated C=C bond, in acetonitrile is an EE process producing stable radical anions and
dianions, whereas the electrochemical oxidation is an EEC (R = Me, Ph) or EE process (R = But) with formation of radical cations (except for the case of R = CF3) and dications (R = But) stable under standard conditions. Radical cations of the dioxides with R = Me, Ph, and But and radical anions of the whole series of the compounds studied, including R = CF3, were characterized by ESR spectroscopy combined with electrochemical measurements and quantum-chemical calculations. The
electrochemical behavior of the But-substituted dinitron is unique: the EE processes in the region of negative and positive potentials with formation of the
dianion, radical anion, radical cation, and dication stable at T = 298 K were observed for the first time within one cycle of potential sweep in the CV curve measured in MeCN.
__________
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1148–1154, May, 2005. 相似文献
52.
Rigol C Olea-Azar C Mendizábal F Otero L Gambino D González M Cerecetto H 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,61(13-14):2933-2938
Cyclic voltammetry and electron spin resonance (ESR) techniques were used in the investigation of several potential antiprotozoal thiosemicarbazones nitrofurane derivatives. A self-protonation process involving the protonation of the nitro group due to the presence of an acidic proton in the thiosemicarbazone moiety was observed in the first step of a CEE(rev) reduction mechanism of these derivatives. ESR spectra of the free radicals obtained by electrolytic reduction were characterized and analyzed. AM1 methodology was used to obtain the optimized geometries and UB3LYP calculations were performed to obtain the theoretical hyperfine coupling constants. The theoretical study exhibited an unusual assignment of the spin densities showing a free radical centered in the thiosemicarbazone moiety rather than the nitro which are in agreement with the experimental hyperfine pattern. 相似文献
53.
用~(57)Fe穆斯堡尔谱研究了炭载型复合催化剂中铁化学形态随温度的变化,及各活性组分、助剂对铁化学形态的影响;并通过ESR谱考察了复合催化剂中不同活性组分对铁在载体炭表面电子特性的影响。研究结果表明,复合催化剂中各活性组分、助剂和载体炭与铁之间存在着强相互作用。在350~650℃,载体炭可将铁从Fe_2O_3还原到Fe_3O_4、FeO、α-Fe和生成炭化铁。活性组分Cu和助剂K可改变催化剂中铁周围的电子密度,促进铁在载体炭上从高价态向低价态还原。同时还发现催化剂中Na和Cr对铁有很强的助分散作用。 相似文献
54.
Mixed-ligand NiIII complexes with -nitroso--naphthol, -nitroso--naphthol,o-ethylxanthate, andN,N-diethyldithiocarbamate as ligands have been studied by ESR in liquid and frozen solutions. The degrees of symmetry distortion for the first coordination sphere of these complexes have been determined. It is shown that the transition from planar square NiIIL2 complexes to more stable octahedral NiIIIL2L and NiIIILL2 complexes occursvia the radical addition mechanism. A method for trapping short-lived radicals is suggested on the basis of the complex formation scheme.Translted fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1513–1515, August, 1995.The work was financially supported by the Russian Foundation for Basic Research (Project No. 93-03-5050) 相似文献
55.
富勒醇清除OH自由基的ESR研究 总被引:8,自引:0,他引:8
富勒醇清除·OH自由基的ESR研究祝严师,孙大勇,刘桂珍,刘子阳,詹瑞云,刘淑莹(中国科学院长春应用化学研究所应用谱学开放实验室,长春,130022)关键词C_(60),富勒醇,OH自由基,自旋捕捉,ESR生物体内的许多现象均涉及到自由基反应,现已发?.. 相似文献
56.
磷酰化肽链中电子转移的ESR研究 总被引:1,自引:0,他引:1
当前生命科学正以前所未有的速度向前发展,从对核酸的深入研究开始过渡到对蛋白质结构与功能的注意,尤其是近年来基因调控研究的重大进展是发现非组蛋白具有高度的磷酸化的特性[1],研究证明,核内蛋白磷酸化和去磷酸化则是基因表达调控的重要方式之一[2,3],它是酶活性调节、基因表达调控、细胞转化恶变的关键环节;同时在解决肿瘤的发生和治疗、病毒的感染和诊治、辐射损伤、抗衰老等实际问题上有突出意义,如1992年Krebus和Fisher因为在蛋白的可逆磷酸化方面的突出贡献而获得诺贝尔生理和医学奖.而电子转移是一切化学变化的基础… 相似文献
57.
Complexes of a rare-earth element containing only one radical-anion ligand have been synthesized and isolated in pure states for the first time. The LaI2(bpy)(THF)3 complex has been prepared from [LaI2(THF)3]2(C10H8) and 2,2-bipyridyl in DME. The semiquinone complex LaI2(SQ)(THF)3 has been obtained by reaction of lanthanum iodide with 3,6-di-tert-butyl-o-benzoquinone in THF in the presence of lanthanum powder. ESR spectra of the complexes have been studied.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2278–2280, November, 1995.We thank Mr. A. V. Protchenko for magnetic measurements and Dr. L. G. Abakumova for recording IR spectra and helpful discussion.This work was supported by the Russian Foundation for Basic Research (Project No. 95-03-08443a). 相似文献
58.
十二烷基甜菜碱与聚乙烯吡咯烷酮相互作用的研究 总被引:2,自引:0,他引:2
通过表面张力测定和13CNMR、ESR波谱研究了十二烷基甜菜碱(C12BE)与聚乙烯吡咯烷酮(PVP)的相互作用.表面张力测定表明,在pH=6.5及NaCI存在下,C12BE与PVP之间有明显的相互作用,可形成C12BE/PVP复合物,且C12BE-PVP混合溶液的β-lgc曲线出现2个转折点,第一个转折点时C12BE浓度c1(C12BE-PVP开始缔合)低于C12BE的cmc值;而第二个转折点时C12BE浓度c2(C12BE-PVP缔合达饱和)大于cmc值.(c2─c1)与PVP浓度呈线性关系.PVP降低C12BE胶束化标准自由能(△G0)随PVP浓度增加而增大.13CNMR测定表明,PVP骨架上α-CH、β-CH2和吡咯环上与N相连的亚甲基吸附于C12BE胶束表面的碳氢链部位,屏蔽了C12BE胶束表面碳氢链与水的接触.ESR波谱表明,PVP-C12BE聚集体"界面"的粘度高于C12BE胶束"界面"的粘度. 相似文献
59.
The review surveys methods for the synthesis, as well as structures and properties of sulfur-containing iron nitrosyl complexes serving as models of active sites of [Fe—S] nitrosyl proteins, which are potential donors of nitrogen monoxide.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2326–2345, November, 2004. 相似文献
60.
以电化学循环伏安、现场ESR电化学以及现场薄层电化学方法研究了电生Co(I)TPP与溴代五己烷的反机制。在DMF中,Co(Ⅱ)/Co(Ⅰ)的氧化还原有明显的催化溴代环己烷还原的特片,反现场有自由基生成,反应产物之一是Co-C键化合物,可以在1.30V(SCE)-电子还原,当存在CH2-CHCN时,。生成另一种Co-C键化合物,该化合物在-1.10V(SCE)处一电子还原,证明溴代环己烷与Co(I) 相似文献