Pressure-Induced Emission Enhancement through a Synergistic Effect between Suppression of Excimer Formation and Activation of Aggregation-Induced Emission

Abstract

Conventional organic π-systems usually suffer from pressure-induced emission quenching due to enhanced π–π stacking, which leads to the formation of dark-state excimer and impedes their high-pressure applications. Herein, we present a new anthracene derivative, 9-(2,2-di([1,1'-biphenyl]-4-yl)vinyl)anthracene (QP-AN), which exhibits significant pressure-induced emission enhancement (PIEE) at 2.49 GPa. Single-crystal analysis reveals a unique π–π dimer packing motif characterized by an exceptionally small interplanar distance (Dπ–π = 3.280 Å) and a minimal overlap area (Sπ–π = 9.57%). Under high pressure, this motif not only suppresses excimer formation by preventing π-plane slippage but also amplifies the aggregation-induced emission (AIE) effect by restricting the motion of the biphenyl rotors in QP-AN. By comparing QP-AN with a control anthracene derivative that exhibits excimer formation and pressure-induced emission quenching, we propose that the synergy between excimer suppression and AIE activation is key to achieving PIEE. Our findings underscore the critical role of modulating excimer formation in AIE system for achieving PIEE.