DC electrical conductivity and conduction mechanism of some azo sulfonyl quinoline ligands and uranyl complexes

Supramolecular coordination of dioxouranium(VI) heterochelates 5-sulphono-7-(4'-X phenylazo)-8-hydroxyquinoline HLn (n = 1, X= CH3; n=2, X= H; n =3, X= Cl; n = 4, X= NO2) have been prepared and characterized with various physico-chemical techniques. The infrared spectral studies showed a monobasic bidentate behavior with the oxygen and azonitrogen donor system. The temperature dependence of the D.C. electrical conductivity of HLn ligands and their uranyl complexes has been studied in the temperature range 305-415 K. The thermal activation energies E-a for HLn. compounds were found to be in the range 0.44-0.9 eV depending on the nature of the substituent X. The complexation process decreased E-a values to the range 0.043-045 eV. The electrical conduction mechanism has been investigated for all samples under investigation. It was found to obey the variable range hopping mechanism (VRH). (C) 2011 Elsevier B.V. All rights reserved.