Some Physico-Chemical Studies on Molecular Semiconductors Based on Charge Transfer Complexes of Substituted Phenothiazines with Iodine

Abstract The synthesis, chemical and structural characterizations, and thermal, spectral, electrical, and magnetic properties of six molecular semiconductors based on the charge transfer complexes of substituted phenothiazines namely; phenothiazine, 2-chlorophenothiazine, 2-(trifluoromethyl)phenothiazine, 2-acetylphenothiazine, N-acetylphenothiazine, and N-benzoylphenothiazine with molecular iodine have been reported in this paper. These complexes have been found to have 2 : 3 stoichiometries. X-Ray diffraction data show that first three complexes have orthorhombic structure whereas the other three are amorphous. Thermal analysis shows that the complexes are thermally stable upto 120 °C. The existence of monomeric and dimeric cationic species of phenothiazines has been proposed on the basis of spectral data. These complexes have been found to be molecular semiconductors having moderately high electrical conductivities and activation energies. The segregated stacking of phenothiazine and iodine moieties has been proposed to be responsible for high conductivity values and a mixed conductivity mechanism accounts for temperature dependence of electrical conductivities of these complexes.