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

Abstract

Synthesis of three novel terpyridine-based donor−acceptor (D-A) ligands (TP1, TP2, TP3) and cyclometalated iridium complexes [Ir(ppy) 2 TP1] + PF 6 − (C1), [Ir(ppy) 2 TP2] + PF 6 − (C2), and [Ir(ppy) 2 TP3] + PF 6 − (C3) [ppy = 2−phenyl pyridine] involving these were described. The ligands and complexes were characterized by spectroscopic studies ( 1 H, 13 C, 19 F, 31 P, 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 CO 2 .

Intermolecular hydrogen bonding-assisted aggregation induced emission in quinolone–quinazoline conjugates and their potential use in acidochromism

“…Cautiously designed push-pull type systems with low energy gap between the ground and excited states together with well separated highest occupied (HOMO) and lowest unoccupied molecular orbitals (LUMO) are beneficial in this regard. 22 Moreover, the detection of volatile acid vapours is crucial in addressing both the industrial and environmental issues. 23 In this direction, methods based on liquid/gas chromatography and near-infrared spectroscopy have drawn special attention.…”

“…Cautiously designed push–pull type systems with low energy gap between the ground and excited states together with well separated highest occupied (HOMO) and lowest unoccupied molecular orbitals (LUMO) are beneficial in this regard. 22…”