New iridium complexes(III) bearing 2-phenylimidazo[4,5-f][1,10]-phenanthroline ligand: Synthesis, characterization, electrochemical and photoluminescence studies

Abstract

Iridium complexes bearing 2-phenylimidazo[4,5-f]-[1,10]-phenanthroline with different substituents (CH3, -CH(CH3)(2), -OCH3, -C6H5) were synthesized and characterized. The effects of different substituents and solvents on the photoluminescence properties of the complexes with [Cl] and [PF6] counter anions have been investigated. The synthesized complexes show high photoluminescence quantum yield due to the extension of the pi-electron conjugation of 2-phenylimidazo[4,5-f][1,10]-phenanthroline ligands. The results indicate that the choice of counter anions ([CI] and [PF6]) has an important influence on the quantum yield of the complexes. In toluene, the compound 4 with phenyl substituent exhibits excimer emission with increasing solution concentrations in the presence of [Cl] counter anion. The linear correlation was observed between the redox potentials of the complexes and Hammett Substituent Constants. The linear correlation can allow the prediction of the effects of substituents on electrochemical studies. (C) 2020 Elsevier B.V. All rights reserved.