Computational Prediction of Pressure-Responsive Luminescence of a D-π-A Compound with Boron–Nitrogen Motifs

Abstract

Under pressure, organic luminescent materials typically display peculiar and fascinating photoluminescence behaviors. Elucidating the luminescence mechanism under pressure is the key to the rational design of piezochromic materials. Here, we carried out an in-depth theoretical investigation of the pressure-responsive behaviors of a highly twisted donor-π-acceptor (D-π-A)-type organoboron compound (FMesB-Cz) by combining dispersion-corrected density functional theory (DFT-D) crystalline-structure simulations, hybrid quantum mechanics/molecular mechanics (QM/MM) calculations, and thermal vibration correlation function formalism. The results reveal that external pressure efficiently suppresses nonradiative decay channels, further elevating its fluorescence quantum yield and producing a moderate pressure-induced emission enhancement (PIEE) effect. Upon compressive loading, FMesB-Cz crystals display distinctive spectral behavior: the absorption band undergoes a redshift, whereas the emission band is blue-shifted, along with intensified vibrational features and disrupted spectral symmetry. Aggregation-induced blue-shifted emission (AIBSE) represents an intriguing photoluminescence phenomenon. An in-depth understanding of its intrinsic mechanism is essential for the development of novel high-performance stimuli-responsive luminescent materials. Through systematic investigation and interpretation of the pressure-dependent luminescent properties of the FMesB-Cz compound, this work uncovers the underlying structure–property relationship in stimuli-responsive systems and offers theoretical guidance for the rational design of pressure-sensitive optoelectronic functional materials.