Aggregation-induced emission of triphenylamine substituted cyanostyrene derivatives

Cyanostyrene-based D-p-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 Phi(F) 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 center dot center dot center dot O, C-H center dot center dot center dot N and C-H center dot center dot center dot pi led to the increased rigidity of the molecular skeleton, which would restrict the intramolecular rotation, yielding high Phi(F) in solid states. These AIE compounds may become candidates for emitting materials.