Electronic Spectra and Electrical Resistivities of the Molecular Complexes of Benzidine and Its Derivatives

The electronic structures of about sixty polycrystalline molecular complexes of benzidine and its derivatives have been examined on the basis of the vibrational and electronic spectra. The complexes show a strong tendency to be non-ionic, in spite of the low ionization potentials of the electron donors. Several non-ionic complexes exhibiting resistivities of the order of 103–105 ohm cm have been found. The optical and electrical properties of the complexes consisting of donor molecules with amino groups and of acceptor molecules with carbonyl groups are distinctly different from those of the others. The first charge-transfer absorption band of the solid complex in the former group appears at an energy considerably lower than that of the corresponding complex in chloroform. Moreover, the activation energy for semiconduction seems to be appreciably reduced by the formation of a hydrogen bond.