ESR and Phosphorescence Spectra of the Triplet States of Phenyl s-Triazines and Phenyl Benzenes

ESR and optical measurements have been made on the lowest triplet state of a series of phenyl s-triazines and polyphenyl benzenes. The features of the phosphorescence spectra and the value of the zero-field splitting parameters of these azines and their hydrocarbon analogs leads to the assignment of the lowest triplet state of the phenyl triazines as (π, π*). The effect of nitrogen substitution is discussed.