Ru(III)-pseudohalide complexes with alkynyl functionalized salicylaldimine ligand and heterocyclic coligand: Synthesis, characterization, electrochemical and luminescence properties

Abstract

A new series of hexa-coordinated Ru(III) complexes of the type [Ru(L)(phen)X2] (1a-3a) and [Ru(L)(bipy)X2](1b-3b) [where, X = NCS, N3, CN] have been prepared by the reaction of RuCl3·H2O with 2-((E)-(4-(2-(4-methoxyphenyl)ethynyl)phenylimino)methyl)-4-(2-(4-methoxy phenyl)ethynyl)phenol (L) in presence of 1,10-phenanthroline (phen) or 2,2′-bipyridine (bipy) as a ligand. The molecular structure of ligand L was confirmed by single crystal X-ray diffraction. All complexes were characterized on the basis of elemental analysis, magnetic moment, TGA, IR, UV–Vis, EPR and mass spectral studies. The EPR spectral data and magnetic susceptibility measurement showed octahedral geometry around Ru(III). The electrochemical properties of all complexes indicate quasireversible redox behaviour corresponding to Ru(III)/Ru(IV) and Ru(III)/Ru(II) couple and are variable to π-acidic character of phen and bipy. All complexes exhibit strong emissions from lowest energy ILCT state with some LMCT character in DMF (10-4 M) at room temperature indicating that alkynyl functionality on salicylaldimine ligand enhances the emission property of the complexes and varies considerably with quenching ability of pseudohalides.