SUBSTITUENT EFFECTS IN THE ELECTROREDUCTION OF PORPHYRINS AND METALLOPORPHYRINS

被引:254
作者
GIRAUDEAU, A
CALLOT, HJ
JORDAN, J
EZHAR, I
GROSS, M
机构
[1] UNIV LOUIS PASTEUR,CHIM ORGAN BIOL LAB,STRASBOURG,FRANCE
[2] PENN STATE UNIV,DEPT CHEM,UNIVERSITY PK,PA 16802
关键词
D O I
10.1021/ja00508a024
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
Electron affinities and electron transfer reactivities of selected mesotetraphenylporphyrin (TPP) moieties have been investigated by controlled potential coulometry, polarography, and cyclic voltammetry. The effect of β-pyrrole substituents (OEt, Cl, Br, SCN, CN, NO2) on the electroreduction of TPP was remarkably large, accounting for polarographic half-wave potential (E½) shifts as great as 0.35 V per substituent, which correlated linearly with Hammett's σp-. Polysubstitution of cyano groups had an additive effect on E½ shifts, but polysubstitution of bromine did not. Insertion of electroreducible cations, such as Mn(III), Fe(III), and Co(II), did not affect the magnitude of the substituent shifts observed on TPP per se. Substituent effects on the E½ of the inserted metal were invariably smaller. Thus, the effect of β substitution on metalloporphyrins provides a simple diagnostic criterion for distinguishing between electron transfer implicating the central cation vs. electrons inserted into the porphyrin ligand. © 1979, American Chemical Society. All rights reserved.
引用
收藏
页码:3857 / 3862
页数:6
相关论文
共 39 条