Computational Design Strategy for Aggregation-Induced Emission Luminogens: Modulating the S₁/S₀ Minimum Energy...

Aggregation-induced emission (AIE) has become a key focus in luminescent material development, with substituent modulation being a critical strategy for expanding AIE systems. The S₁/S₀ minimum energy conical intersection (MECI) significantly influences molecular photophysical properties, making it essential for understanding the AIE phenomenon. Here, we employ anthracene derivatives, known for their chemical versatility and applications in organic light-emitting diodes (OLEDs), to systematically investigate the effects of substituents on the S₁/S₀-MECI. We select 22 anthracene derivatives with varied electron-donating and electron-withdrawing substituents and explore their impacts on the S₁/S₀-MECI relative energy and molecular structure. Our findings reveal that strong electron-donating or electron-withdrawing groups at the C9-position effectively lower the S₁/S₀-MECI relative energy of the gaseous phase singly substituted anthracene derivatives, thus enhancing the AIE phenomenon of such molecules. Additionally, doubly substituted derivatives on the same ring also slightly reduce the S₁/S₀-MECI relative energy of the isolated molecule. Based on these insights, we propose a novel AIE molecular design strategy focusing on modulating S₁/S₀-MECI through strategic substituent selection, leading to the identification of 24 AIEgens candidates among 81 anthracene derivatives. In summary, our study provides a systematic approach to designing AIE molecules by modulating the S₁/S₀-MECI through a substituent effect. The validity of this strategy is confirmed using the 9-tBu-Ant molecule with quantitative calculations.