Some Environmental Effects on the shf Lines in the ESR Spectra of Vanadyl Tetraphenylporphin

The ESR spectra of vanadyl tetraphenylporphin (VOTPP) have been studied in a number of organic matrices, with special attention paid to the resolution of the nitrogen shf lines. The matrices were classified into three groups according to their effects on the resolutions of the vanadium hf lines and of the nitrogen shf lines. In the A-group matrices, the spectra of VOTPP displayed well-resolved hf lines, accompanied by shf splittings; in the B-group matrices, the spectra gave rise to well-resolved hf lines, but without shf splittings, and in the C-group matrices, the hf lines were resolved only poorly. It is suggested that a high dispersion of VOTPP molecules is required for the higher resolution of spectra.