High-contrast mechanofluorochromism of two AIE-active D-A-π-D′ deep red-emitting triphenylamine-based dicyanodiaryl derivatives

作者：Hanrong Liu, Baobei Liu, Huizhuan Zhu, Jiakun Bai, Huijuan Zhang, Junhui Jia · 发表于：Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy · 年份：2025 · DOI：10.1016/j.saa.2025.126666 · 被引用次数：6 · 研究领域：Luminescence and Fluorescent Materials、Molecular Sensors and Ion Detection、Photochromic and Fluorescence Chemistry

In this study, we successfully constructed two AIE-active D-A-π-D' red-emitting triphenylamine-based dicyanodiaryl derivatives, namely (E)-2-(1-(4-(diphenylamino)phenyl)-3-(4-hydroxyphenyl)allylidene)malononitrile (p-DPHAM) and (E)-2-(1-(4-(diphenylamino)phenyl)-3-(3-hydroxyphenyl)allylidene)malononitrile (m-DPHAM). A comprehensive photophysical characterization combined with theoretical calculations elucidated their non-planar, twisted molecular conformations, donor-acceptor frameworks, and notable solvatochromic properties. Both compounds demonstrated pronounced AIE behavior in THF-water mixtures. These two derivatives displayed remarkable mechanofluorochromic behavior with a red-shift for p-DPHAM (52 nm) and m-DPHAM (41 nm), respectively. Powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC) and field-emission scanning electron microscopy (FESEM) analyses indicated that the reversible mechanofluorochromism originates from crystalline-to-amorphous phase transitions. Single-crystal structural analysis revealed that external mechanical force disrupted specific intramolecular interactions, leading to a transformation in stacking pattern. It is anticipated that this work offers valuable perspectives for the design of high-contrast mechano-responsive luminescent materials.