Tunable Mechanoresponsive Behaviors of Lewis Adducts via B←N Coordination and Corresponding Application

Although mechanically responsive luminescent materials exhibit substantial potential for information security applications, developing organic systems that combine high contrast ratio, rapid response kinetics, and excellent fatigue resistance remains a formidable challenge. Herein, a Lewis adduct PTBrBA is constructed via B←N coordination, which displays remarkable response under external force. Upon anisotropic grinding and fuming, PTBrBA shows a highly reversible mechanochromic shift from cyan-blue to green. Moreover, under isotropic hydrostatic pressure, it exhibits full-color piezochromic behavior with a continuous redshift from 477 to 668 nm, reaching up to 191 nm. This pronounced redshift results from pressure-induced B←N bond shortening and anisotropic lattice contraction, which cooperatively enhance intra-/inter-molecular charge transfer (CT). At low pressure (<0.4 GPa), the enhanced structural rigidity suppresses non-radiative decay, boosting emission intensity. At higher pressure, the amorphization and stronger π–π stacking promote non-radiative decay, causing emission quenching. Notably, after full pressure release, PTBrBA retains partial structural distortion and long-range disorder, resulting in irreversible optical responses with enhanced intermolecular CT. Finally, PTBrBA shows significant potential in information encryption and anti-counterfeiting applications, enabling vapor-responsive decryption, reversible writing/erasing, and excitation-dependent multicolor patterning. This work offers new perspectives and molecular platforms for designing smart optical systems based on dynamic coordination bonds.