Preparation and spectroscopic properties of pure tetrabenzoporphyrins

Abstract

Cadmium tetrabenzoporphyrin, tetrabenzoporphyrin, and the bispyridine complex of magnesium tetrabenzoporphyrin were synthesized. As judged from the visible absorption spectra these compounds are not contaminated with porphyrin-like impurities. 100-MHz ¹H Fourier-transform n.m.r. spectra of the above mentioned compounds are presented. From the low-temperature e.s.r. spectra it can be concluded that the lowest triplet state of biligated magnesium tetrabenzoporphyrin exhibits a static Jahn–Teller distortion resulting in a loss of four-fold molecular symmetry.