Benzo[g]quinoxaline-Based Complexes [Ir(pbt)₂(dppn)]Cl and [Ir(pt)₂(dppn)]Cl: Modulation of Photo-Oxidation Activity and Light-Controlled Luminescence

Abstract

Based on benzo[i]dipyrido[3,2-a:2′,3′-c]phenazine (dppn) with photo-oxidation activity, complexes [Ir(pbt) 2 (dppn)] Cl (1) and [Ir(pt) 2 (dppn)]Cl (2) have been synthesized (pbtH = 2-phenylbenzothiazole, and ptH = 2-phenylthiazole), with two aims, including studying the influence of the cyclometalating ligands (pbt − in 1, pt − in 2) on the photo-oxidation activity of these complexes and exploring their photo-oxidation-induced luminescence. Both 1 H nuclear magnetic resonance (NMR) and electrospray (ES) mass spectrometry indicate that the benzo[g]quinoxaline moiety in complex 1 can be oxidized at room temperature upon irradiation with 415 nm light. Thus, this complex in CH 2 Cl 2 shows photo-oxidation-induced turn-on yellow luminescence. In contrast, complex 2 reveals significant structural decomposition during the process of photo-oxidation due to incorporating a cyclometalating ligand pt − instead of pbt − in complex 1. In this paper, we report the photo-oxidation behaviors and the related luminescence modulation in 1 and 2 and discuss the relationship between structure and photo-oxidation activity in these complexes.