Cyclometalated Ir(III) Complexes Involving Functionalized Terpyridine-Based Ligands Exhibiting Aggregation-Induced Emission and Their Potential Applications in CO2 Detection

Synthesis of three novel terpyridine-based donor–acceptor (D-A) ligands (TP1, TP2, TP3) and cyclometalated iridium complexes [Ir(ppy)2TP1]+PF6– (C1), [Ir(ppy)2TP2]+PF6– (C2), and [Ir(ppy)2TP3]+PF6– (C3) [ppy = 2−phenyl pyridine] involving these were described. The ligands and complexes were characterized by spectroscopic studies (1H, 13C, 19F, 31P, ESI-MS, UV-vis, and fluorescence). Crucial role of intermolecular interactions in aggregation-caused quenching (ACQ; C2) and aggregation-induced emission (AIE; C3) was rationalized by X-ray single-crystal analyses. Vital role of restricted intramolecular rotation (RIR) in inducing AIE upon aggregation via π–π interactions in these complexes was scrutinized by various studies. Because of strong intramolecular charge transfer these D−A based AIEgens exhibited solvatochromism. Further, AIE property of the complexes C1 and C3 was exploited toward detection of CO2.