THE DIRECT-CURRENT ELECTRICAL-CONDUCTIVITY OF THE CHARGE-TRANSFER COMPLEXES OF SOME THIAZOLES AND BENZOTHIAZOLES WITH CERTAIN DINITROBE AND TRINITROBENZENE DERIVATIVES

The DC electrical conductivity of 2-aminothiazole (I), 2-aminobenzothiazole (II), 2-amino-4-methylbenzothiazole (III) and 2-amino-6-nitrobenzothiazole (IV) and their charge transfer (CT) complexes with the acceptors, 1,3-dinitrobenzene (1), 3,4-dinitrobenzoic acid (2) and picric acid (3) were investigated. The positive temperature coefficients of the electrical conductivity of these thiazoles suggested their semiconducting characteristics. The CT complexes were classified into two main groups. The first group included the complexes I1, I2 and IV1,2,3. All these complexes had negative temperature coefficients of resistance and revealed conventional semiconducting behaviour. Two different activation energies for the complexes I2, IV2 and IV3 indicated the presence of more than one conduction mechanism. The second group contained the complexes I3, II1,2,3 and III1,2,3. The thermal conductivity plots exhibited curves with two inflections and three regions. The slope of the line of a region and also its temperature range were found to depend upon the nature and structure of the complex. No correlation was found between the activation energies of the CT complexes and either the electron affinities of acceptors or the ionization potentials of donors. This was explained by assuming that the geometrical, and not the electronic, structure of the complexes was the determining factor.