Electrical and spectral studies of modified solid semiconductors

Abstract

Diazoaminobenzene shows semiconducting properties and a phenomenon of phase transition. The semiconducting properties arise as a result of high molecular resonance induced by intramolecular hydrogen bonding at the cliazo linkage. The phase transition is probably a consequence of thermal rotation into resolved cis and trans configurations; the frans form conducts electricity with a lower activation energy assisted by the molecular resonance. Thermal rotation into the more thermally stable cis form reduces the molecular resonance so that the resultant form conducts electricity with a higher activation energy. Unexpectedly, chelation with the favoured d-block element, Cu, reduces the electrical conductivity which is evidenced by a reduced electric dipole moment. Chelation appears to proceed favourably at the cis form, since the resultant complex conducts electricity with a similar high activation energy, a result of prohibited proton exchange. Restricted rotation in the Cu chelate explains conduction via a single phase. Consistent data from ¹H-NMR, i.r. and u.v.—visible spectra do confirm the proposed structural interpretation.