The Cation Radical Salts of Phenothiazine and Related Compounds

Abstract

Abstract The cation radical salts of phenothiazine bromide, phenothiazine bisulfate monohydrate, and phenothiazine picrate were prepared. The absorption spectra in a dilute hydrochloric acid solution and the solid-state spectra of the salts were examined. The solid-state spectra showed a strong charge-transfer band and blue-shifts of the high-energy bands, unlike the absorption spectra in solution. The magnetic susceptibilities of these salts were measured at room temperature. They were found to be diamagnetic, with values almost corresponding to those of the diamagnetic contribution of the salts, except for that of the picrate. These spectroscopic and magnetic properties were discussed on the basis of the charge-transfer interaction between the phenothiazine cation radicals. The properties of the usual phenothiazine-picric acid charge-transfer complex and the holoquinoid phenothiazine perchlorate were investigated in association with those of the cation radical salts.