Yunnan Key Laboratory of Metal-Organic Molecular Materials and Device, School of Chemistry and Chemical Engineering, Kunming University, Kunming, P.R. China.
Chromatographic Analysis Center, Dali Institute for Food Control, Dali, P.R. China.
Luminescence. 2024 Apr;39(4):e4729. doi: 10.1002/bio.4729.
To further explore the relationship between aryl substituents and mechanofluorochromic (MFC) behaviors, four salicylaldimine-based difluoroboron complexes (ts-Ph BF, ts-Ph-NA BF, ts-2NA BF, and ts-triphenylamine [TPA] BF), including aromatic substituents with different steric hindrance effects, were designed and successfully synthesized. Four complexes with twisted molecular conformation displayed intramolecular charge transfer and aggregation-induced emission properties. Under external mechanical stimuli, the as-synthesized powders of ts-Ph BF, ts-Ph-NA BF, and ts-TPA BF exhibited redshift fluorescence emission behaviors, and ts-Ph BF and ts-TPA BF could be recovered to original shifts by fuming, but ts-Ph-NA BF displayed irreversible switching. ts-2NA BF had no change during the grinding and fuming processes. The results indicated that the MFC behaviors could be attributed to the phase transformation between the well-defined crystalline and disordered amorphous states by X-ray diffraction measurement. Further research illustrated that ts-TPA BF with the most significant MFC phenomenon could be applied in data security protection in ink-free rewritable paper.
为了进一步探索芳基取代基与机械变色（MFC）行为之间的关系，设计并成功合成了四种基于水杨醛亚胺的双氟硼配合物（ts-Ph BF、ts-Ph-NA BF、ts-2NA BF 和 ts-三苯胺[TPA] BF），包括具有不同空间位阻效应的芳基取代基。四种具有扭曲分子构象的配合物表现出分子内电荷转移和聚集诱导发射性质。在外部机械刺激下，合成的 ts-Ph BF、ts-Ph-NA BF 和 ts-TPA BF 粉末表现出红移荧光发射行为，并且 ts-Ph BF 和 ts-TPA BF 可以通过冒烟恢复到原始位移，但 ts-Ph-NA BF 表现出不可逆的切换。ts-2NA BF 在研磨和冒烟过程中没有变化。结果表明，MFC 行为可归因于 X 射线衍射测量中明确的结晶和无序非晶态之间的相转变。进一步的研究表明，具有最显著 MFC 现象的 ts-TPA BF 可应用于无墨可重写纸上的数据安全保护。
