One- and two-electron reduction of aluminum and tin pyridylporphyrins. A kinetic spectrophotometric study
One- and two-electron reduction of aluminum and tin pyridylporphyrins. A kinetic spectrophotometric study
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铝和锡吡啶基卟啉的一电子和二电子还原。
DOI：
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发表时间：
1984
期刊：
影响因子：
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通讯作者：
P. Neta
中科院分区：
文献类型：
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作者：
S. Baral;P. Hambright;P. Neta
Al/sup III/TPyP（TPyP =四-4-吡啶基卟啉），Al/sup III/TMPyP（TMPyP =四（N-甲基-4-吡啶基）卟啉）、Sn/sup IV/TMPyP、Sn/sup IV/TPP（TPP =四苯基卟啉），Sn/sup IV/TPMMPyP（TPMMPyP =三苯基单（N-甲基-4-吡啶基）卟啉），和Sn/sup IV/TPMPyP用稳态和脉冲辐解分光光度法研究了三苯基单-4-吡啶基卟啉（TPMPyP）在中性和碱性水溶液及甲醇溶液中的显色反应。这两种铝卟啉（Al/sup III/P），在中性和碱性甲醇，进行单电子还原，形成瞬态物种，表现出最大吸收波长分别在700和740 nm，因此其特征在于作为配体自由基（Al/sup III/P/sup -/）。这些物种通过反硝化作用衰变，二级速率常数约为10/sup 8/-10/sub 9/。最终产物取决于卟啉和介质的性质，但主要是根皮素（Al/sup III/PH/sub 2/或Al/sup III/PH/sup -/）。讨论了影响最终产品形成的因素。吡啶基卟啉锡（IV）形成单电子还原物种（Sn/sup IV/P/sup -/），其在碱性水溶液和甲醇溶液中稳定。这些产物可以进一步还原得到根皮素。在中性或酸性溶液中，1 e-还原产物迅速歧化成根皮素和卟啉。Sn/sup IV/TPP表现出不同的行为，因为1 e-还原的物种的寿命不是很长，2 e-还原产物主要是二氢卟酚而不是佛林。20参考文献，更多» 7图，2表。«少
Al/sup III/TPyP (TPyP = tetra-4-pyridylporphyrin), Al/sup III/TMPyP (TMPyP = tetrakis(N-methyl-4-pyridyl)porphyrin), Sn/sup IV/TMPyP, Sn/sup IV/TPP (TPP = tetraphenylporphyrin), Sn/sup IV/TPMMPyP (TPMMPyP = triphenylmono(N-methyl-4-pyridyl)porphyrin), and Sn/sup IV/TPMPyP (TPMPyP = triphenylmono-4-pridylporphyrin) were studied by steady-state and pulse radiolysis spectrophotometric techniques in neutral and alkaline aqueous and methanolic solutions. Both aluminum porphyrins (Al/sup III/P), in neutral and basic methanol, undergo one-electron reduction to form transient species which exhibit absorption maxima at 700 and 740 nm, respectively, and are thus characterized as ligand radicals (Al/sup III/P/sup -/). These species decay by disproportionation with second-order rate constants of approx.10/sup 8/-10/sub 9/. The final products depend on the nature of the porphyrin and the medium but are mainly phlorins (Al/sup III/PH/sub 2/ or Al/sup III/PH/sup -/). Factors which influence the formation of final products are discussed. The tin(IV) pyridylporphyrins form one-electron-reduced species (Sn/sup IV/P/sup -/) which are stable in alkaline aqueous and methanolic solutions. These products can be further reduced to give the phlorin. In neutral or acidic solutions the 1e-reduction products disproportionate rapidly into phlorin and porphyrin. Sn/sup IV/TPP exhibits a different behavior in that the 1e-reduced species in not very long-lived and the 2e-reduction product is mainly a chlorin rather than a phorin. 20 references,more » 7 figures, 2 tables.« less