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Triphenylamine functionalized salicylaldimine difluoroboron complexes bearing different substituents have been synthesized. The photophysical results showed that these complexes exhibited intramolecular charge transfer (ICT) emission and solvatochromism. The fluorescence of these complexes could be well-tuned by the substituents in the ligands. The introduction of tert-butyl groups causes the complex TST to show obvious aggregation-induced emission (AIE) activity. In particular, the complexes without other substitutions or with the substitutions of bromo, tert-butyl and methoxyl on salicylaldimine moieties displayed reversible mechanofluorochromic (MFC) behaviors. XRD patterns and DSC curves of the complexes in different solid states suggested that the transformation between crystalline and amorphous states was responsible for the MFC properties. The relationship between the molecular structures and MFC properties suggested that the high polarity of the conjugated skeletons in difluoroboron complexes was beneficial for realizing high-contrast performance in mechanofluorochromism. [ABSTRACT FROM AUTHOR]

New D–π–A-type triphenylamine-containing benzimidazoles, benzoxazoles and benzothiazoles have been synthesized. It was found that the introduction of a cyano group in vinyl and methyl in triphenylamine was favorable for producing mechanofluorochromism of the fused heterocyclic derivatives. The single crystal X-ray diffraction data revealed that the intermolecular interactions of the H-bonding formed from the cyano group and the C–H…π interaction formed from the methyl group would rigidify the molecular conformations, leading to strong solid-state emission. Interestingly, the solid-state emission of the synthesized triphenylamine-containing fused heterocycles bearing cyano and/or methyl groups could be tuned by external mechanical forces on account of the transition between crystalline and amorphous states or between a highly ordered crystalline state and a less ordered state. [ABSTRACT FROM AUTHOR]

Cyanostyrene-based D–π–A type conjugated compounds bearing triphenylamine units (G1, G1-N and G2) have been synthesized. By tuning the conjugated skeleton and the electron withdrawing ability of the acceptor, green, orange and red light emitters were achieved. It is interesting that although their emissions in solutions were weak, we observed strong emission in solid states. For example, the ΦF of the dendritic molecule G2 in powder reached 0.67, which was more than 20 times of that in THF. The single crystal X-ray diffraction data revealed that the intermolecular H-bonds of C–H…O, C–H…N and C–H…π led to the increased rigidity of the molecular skeleton, which would restrict the intramolecular rotation, yielding high ΦF in solid states. These AIE compounds may become candidates for emitting materials. [ABSTRACT FROM AUTHOR]