Effects of Iodine Addition on the Electrical and Optical Properties of the Semiquinoid Phenothiazine Bromide

The electrical resistivity and the electronic and vibrational spectra of the semiquinoid phenothiazine bromide have been found to be drastically modified by the addition of iodine. The resistivity minimum lies around the mole ratios of 0.25 to 0.30, while the value in this composition range is from 4 to 5 ohm cm. The combined spectroscopic data indicate three different stages in the intermolecular interactions in this system; the first around a mole ratio of 0.25, the second near 0.5, and the third above 1.00. The higher the iodine content, the less conductive the adducts appear to be. Iodine addition was attempted also to the p-phenylenediamine bromide; however, no pronounced effect on the physical properties could be found in this system.