REDOX CHEMISTRY OF METALLOPORPHYRINS IN AQUEOUS-SOLUTION
REDOX CHEMISTRY OF METALLOPORPHYRINS IN AQUEOUS-SOLUTION
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DOI：
10.1021/j150642a038
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发表时间：
1983-01-01
影响因子：
--
通讯作者：
NETA, P
中科院分区：
文献类型：
--
作者：
HARRIMAN, A;RICHOUX, MC;NETA, P
合成了一系列水溶性金属卟啉化合物，并利用电化学和脉冲辐解技术研究了它们的氧化还原化学。所有的金属卟啉都表现出相当强的吸收跃迁（upper = ca. 2 × 10/sup 4/ dm/sup 3/ mol/sup-1/ cm/sup-1/）和430 nm附近的强吸收（上吸收=（2-7）× 10/sup 5/ dm/sup 3/ mol/sup-1/ cm/sup-1/）。循环伏安法表明，化合物进行明确的还原和氧化步骤，虽然氧化过程是不可逆的。对于抗磁性金属卟啉，对于特定化合物，添加和去除电子之间的E/sub 1/2/的差为2.05 +/-0.20 V，而添加一个和两个电子之间的E/sub 1/2/的差为0.28 +/-0.12 V。pi..该体系比去除第一个电子的体系高0.25 +/-0.10V，这与中心金属离子对卟啉只产生诱导作用的结果一致。pi..程度.用脉冲辐解方法记录了单电子还原和氧化产物的吸收光谱。这两种产品都表现出跨越整个可见光和近红外区域的宽吸收跃迁。还原产物经鉴定为。pi..-自由基阴离子，并且在许多情况下，这些自由基阴离子对于反离子化是不稳定的。氧化产物经鉴定为。pi..-自由基阳离子，这些在水溶液中也不稳定，但衰变途径仍然不清楚。参考文献44篇，图6幅，表3张。
A series of water-soluble metalloporphyrins has been prepared and the redox chemistry investigated by electrochemical and pulse radiolytic techniques. All of the metalloporphyrins exhibit reasonably intense absorption transitions (upsilon = ca. 2 x 10/sup 4/ dm/sup 3/ mol/sup -1/ cm/sup -1/) in the visible region and a strong absorption (upsilon = (2-7) x 10/sup 5/ dm/sup 3/ mol/sup -1/ cm/sup -1/) around 430 nm. Cyclic voltammetry showed that the compounds undergo well-defined reduction and oxidation steps, although the oxidation processes were not really reversible. For diamagnetic metalloporphyrins, the difference in E/sub 1/2/ between addition and removal of an electron for a particular compound was 2.05 +/- 0.20 V while the difference in E/sub 1/2/ between addition of one and two electrons was 0.28 +/- 0.12 V. Similarly, E/sub 1/2/ for the removal of a second electron from the porphyrin ..pi.. system was some 0.25 +/- 0.10 V higher than that for removal of the first electron. These findings are consistent with the central metal ion exerting only an inductive effect upon the porphyrin ..pi.. levels. The absorption spectra of the one-electron reduction and oxidation products were recorded by pulse radiolysis methods. Both products exhibit broad absorption transitions stretching across the entire visible and near-IR regions. The reduction products were identified as ..pi..-radical anions and, in many cases, these were unstable with respect to disproportionation. The oxidation products were identified as ..pi..-radical cations and these were also unstable in aqueous solution but the decay route remains obscure. 44 references, 6 figures, 3 tables.