摘要
Thermally activated delayed fluorescence (TADF) emitters with stimuli-responsive behavior hold great potential for applications in dynamic optoelectronics and sensing. Herein, we report the design and synthesis of two novel diboraanthracene (DBA) derivatives incorporating twisted azepine-type donors, iminodibenzyl (IDB) and iminostilbene (ISB), to afford two compounds IDBDBA and ISBDBA. They display orange-to-red TADF, narrow singlet-triplet energy gaps, and high reverse intersystem crossing (RISC) rates, attributed to their rigid donor-acceptor conformations, as confirmed by single-crystal X-ray diffraction (XRD) and theoretical calculations. Notably, ISBDBA demonstrates a mechanically induced enhancement in photoluminescence quantum yield (PLQY), increasing by more than twofold, accompanied by a slightly redshifted emission at 603 nm. The reversible behavior is attributed to crystallinity loss upon grinding, as supported by powder XRD analysis. Our results highlight the effectiveness of twisted azepine donors integrated into the DBA scaffold in promoting TADF activity, offering a promising strategy for developing stimuli-responsive luminescent materials.
•Two azepine donors were employed to construct D-A-D-type diboraanthracene (DBA) derivatives, named IDBDBA and ISBDBA•Both emitters show orange-to-red TADF with narrow ΔEST values (0.04 eV) and high RISC rates up to 6.23 × 106 s−1.•Calculations support their excited-state features, conformational distortion, and rigid solid-state structure.•Neat ISBDBA shows responsive PLQY enhancement upon grinding, attributed to reduced crystallinity confirmed by PXRD.