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.

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.