Electrochemical, Spectroelectrochemical, and Dielectric Properties of Metallophthalocyanines Bearing Redox Active Cobalt and Manganese Metal Centers
By Uzunmehmeto?lu, Hilal Zengin; Yenilmez, H. Yasemin; Kaya, Kerem; Koca, At?f; Alt?ndal, Ahmet; Bay?r, Zehra Altunta?
Published in Inorganica Chimica Acta
2017
Abstract
Abstract We report herein the synthesis of symmetrical metallophthalocyanines having cobalt, zinc, and manganese as the metal ions, and having tetrakis(4-phenyl-1,3-thiazole-2-thiolate) groups substituted at the peripheral positions of the phthalocyanine. Electrochemical responses of the complexes were determined with voltammetric and in situ spectroelectrochemical measurements. Cobalt and ?-oxo manganese phthalocyanines (CoPc and ?-oxo MnPc) illustrated metal-based electron transfer reactions in addition to the Pc based reactions. ?-oxo-manganese phthalocyanine exhibited completely different redox properties than those of the monomeric manganese phthalocyanine. Thiazole substituents of the complexes caused oxidative electropolymerisation of the complexes on the working electrode. Electropolymerised ?-oxo manganese phthalocyanine catalyzed oxygen evolution reaction (OER) in basic aqueous solution. The ac behaviour of the tetrasubstituted metallophthalocyanines was studied by impedance spectroscopy technique over a temperature range of 300-450 K and frequency of 100 Hz.-13 MHz. The results show that the new compounds exhibit abnormally high dielectric constants even at room temperature. It was concluded that Maxwell-Wagner polarisation is an appropriate model to explain the behaviour of the dielectric function at low frequencies. Frequency dependent measurements revealed that the compounds exhibits non-Debye type relaxation behaviour.