Synergistic regulation of AIE property by J-/H-aggregates and TICT in a cationic iridium complex.

The photophysical properties of phosphorescent iridium complexes are intricately governed by the interplay between intermolecular packing and intramolecular processes. In this work, we report a cationic iridium complex whose aggregation-induced emission (AIE) property is synergistically regulated by the formation of J- or H-aggregates and the twisted intramolecular charge transfer (TICT) effect inherent to its donor-acceptor ligand. The emission characteristics exhibit a pronounced dependence on the water fraction in THF/water mixtures. Through a combination of single-crystal analysis, AFM/HR-TEM, and TD-DFT calculations, we elucidate that specific non-covalent interactions dictate the molecular packing, while the TICT process, active in solution, is effectively suppressed upon aggregation. Additionally, solvation of the counter anion at elevated water fractions is identified as a critical factor contributing to emission quenching. This study provides deep insights into the cooperative roles of TICT and distinct aggregate types in manipulating the luminescence of iridium complexes, establishing a strategic guideline for the design of advanced AIE-active materials with highly promising practical applications in areas such as latent fingerprint identification and environmental stimuli-responsive smart sensors.