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The chemical processes of tryptophan (Trp), tyrosine (Tyr) and a dipeptide Trp-Tyr, which are induced by UV radiation and one-electron oxidation of SO.
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–, have been investigated in aqueous solution by KrF (248 nm) laser flash photolysis. On the basis of optical studies, the photoionization of Trp and Tyr produces the tryptophan indolyl radical and tyrosine phenoxyl radical, respectively, and these are different from the intermediates resulting from interaction of Trp and Tyr with SO.
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–. In the case of Trp, SO.
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– would attack the indole moiety to produce a C(2)-yl sulphate radical adduct, and Tyr is oxidized to produce mainly the corresponding one-electron oxidized radical, which deprotonates rapidly to form the phenoxyl radical in neutral solution, and a possible sulphate radical adduct. From transient absorption spectra of photoionization of Trp-Tyr, an intramolecular electron transfer, Trp/N.-Tyr Trp-Tyr/O., has been observed, but there was no observation of the process of one-electron oxidation of Trp-Tyr by SO.
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–. 相似文献
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用高时间分辨电子自旋共振(TRESR)波谱仪, 研究对苯醌(PBQ)在不同的介质中光解苯半醌自由基的化学诱导动态电子自旋极化(CIDEP)。实验结果指出, 在乙二醇溶液中得到苯半醌自由基(PBQH)和以碳为中心的自由基R(OH)2。在乙二醇/水溶液中, 得到以PBQH的六条峰为主的谱线图, 然后在该体系中随着加入表面活性剂TX-100, AOT的浓度增加, 苯半醌负离子基(PBQ^-)的谱线强度增加, 而PBQH的谱线减弱直至消失。本文从自由基所处微环境性质出发, 讨论其极化传递机理和有关物理化学性质。 相似文献
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Wen Li 《Research on Chemical Intermediates》2004,30(3):311-316
Time-resolved transient absorption spectra have been obtained first for mesitylene by 355 nm laser flash photolysis at ambient temperature. Mono- and biradicals were observed in the experiment, in which the transient absorption peak at about 370 nm was assigned to the biradical and the peak at about 580 nm to the monoradical; the biradical has a longer lifetime than the monoradical. According to the representative value of the C-H bond dissociation energy for aromatic compounds monoradical formation might be a single-photon process. For comparison with the absorption spectra the time-resolved fluorescence spectra were obtained and also the biradical was assigned to about 393 nm. 相似文献
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芳环取代的俘精酸酐的合成及光致变色反应研究 总被引:1,自引:0,他引:1
本文报道四个芳环取代的俘精酸酐:2-亚异丙基-3-[1-(4-甲氧苯基)-亚乙基]-丁二酸酐(BF1); 2-亚异丁基-3-[1-(4-甲氧苯基)-亚乙基]-丁二酸酐(BF2);2-亚异丙基-3-[1-(α-萘基)-亚乙基]-丁二酸酐(NF1); 2-亚异丙基-3-[1-(β-萘基)-亚乙基]-丁二酸酐(NF2)的合成及其光致变色性质。测定了它们在不同溶剂中光致变色前后的吸收光谱。利用纳秒级激光闪光光解技术研究了它们的光致变色过程, 并讨论了其光致变色机理。结果表明, 这类芳环取代的俘精酸酐的光致环合反应是经过激发单重态进行的快速过程。 相似文献
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UV Irradiation of cyclohexane solution of bicyclo[2.2.2]octenediones led to facile extrusion of carbon monoxide to give substituted dihydrobiphenyls along with the dehydrogenated products. The inseparable mixtures on DDQ oxidation afforded the biphenyl derivatives. Isolation of an intermediate arising from the initial monodecarbonylation lends support to a proposed mechanistic rationalization. 相似文献
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本文对硫代苯甲酸-S-苯酯类化合物的敏化光解反应进行了研究, 以图扩大其光谱响应范围。工作表明硫代苯甲酸-S-苯酯能与芘、北等敏化剂发生电子转移反应, 并进而促使硫代苯甲酸-S-苯酯分子裂解, 产生各种分解产物; 气相色谱-质谱联用仪分析结果表明, 敏化光解产物主要为苯甲醛和二苯基二硫醚,在此基础上对标题化合物敏化光解的机制提出了看见。此外, 从该光敏体系能引发甲基丙烯酸甲酯聚合进一步表明, 硫代苯甲酸-S-苯酯能与适宜的电子给体组成光敏引发体系, 使该体系的光敏引发可用波长扩展到400nm以上。 相似文献