A difluoroboron compound with latent fingerprint detection and inkless writing based on aggregation-induced emission enhancement and mechanofluorochromic behavior

A novel pyridine-based difluoroboron compound containing a triphenylamine moiety was designed and synthesized. It exhibited intramolecular charge transfer features and aggregation-induced emission enhancement (AIEE) activity, as well as reversible mechanofluorochromic behavior upon grinding–fuming. The photophysical properties in solutions were explained by molecular simulation, and the results of XRD patterns and X-ray single crystal analyses illustrated that the switching of crystalline–amorphous states and the planarization of the molecular conformation in the solid state upon grinding gave rise to mechanofluorochromic behavior. Additionally, under 365 nm UV light, this compound was successfully used for latent fingerprint visualization testing due to its excellent AIEE activity, and inkless writing testing due to its solid-state color with high brightness and contrast upon grinding–fuming.