Binding of Imidazoles and Pyridines to the Atropisomers of Zinc Tetra(ο-pivalamidophenyl)porhyrin

概要

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Complex formation of four atropisomers of zinc tetra(ο-pivalamidophenyl)porphyrin with imidazoles (imidazole, 1-methylimidazole, 2-methylimidazole, and benzimidazole) and pyridines (pyridine, 3,5-dimethylpyridine, and 2,6-dimethylpyridine) was studied. The ratios of the absorbance of the βband to the αband in the adducts tended to be in the order of αααα>ααββ≧αααβ>αβαβ. This order, which is the same as that of "electronic effect" on the physical properties of the four atropisomers of tetra(ο-pivalamidophenyl)porphyrin, indicates the presence of "electronic effect" in the zinc derivatives of the porphyrin. Among the four isomers, the equilibrium constants of N-base binding tended to be in the order of αβαβ>αααα≧αααβ>ααββ, suggesting the relatively greater importance of "steric effect" of the bulky pivalamido groups rather than "electronic effect" for the coordination of the N-bases. The differences in the equilibrium constants among the atropisomers are attributable to the contributions of both the steric effect and the electronic effect.
社団法人日本薬学会の論文
1986-05-25