Study on mechanofluorochromism, ink-free writing, and latent fingerprint imaging of the functionalized difluoroboron compounds with methyl and methoxy

Two difluoroboron compounds including amide linkage moiety, compound F-1 with methoxy group and compound F-2 with methyl group, were designed and successfully synthesized. The results indicated that the solid powders of two compounds both displayed mechanofluorochromism phenomena, which originated from phase transformation between the well-ordered microcrystalline and amorphous states, and the intramolecular charge transfer, as well as the mechanofluorochromism of compound F-1 was better than that of compound F-2 due to larger dipole moment change value between the ground and excited states. Additionally, compound F-1 had more twisted molecular spatial conformation, which exhibited aggregation-induced emission in mixtures of THF/water, yet compound F-2 was observed aggregation-caused quenching phenomenon. It was gratified that two compounds had the potential application in the field of ink-free writing owing to their reversibly mechanofluorochromism behaviors, not only that, compound F-1 could be used to latent fingerprint imaging because of its aggregation-induced emission feature. Two difluoroboron compounds including amide linkage moiety, compound F-1 with methoxy group and compound F-2 with methyl group, were designed and successfully synthesized. They possessed reversibly mechanofluorochromism behaviors, and could be applied in the field of ink-free writing. Importantly, compound F-1 could be used to latent fingerprint imaging because of its aggregation-induced emission feature. [Display omitted] •Two difluoroboron compounds with amide bond linkage moiety, compound F-1 with methoxy unit and compound F-2 with methyl group, were synthesized.•Two compounds had a potential application in the field of ink-free writing based on their reversible mechanofluorochromism behaviors.•Compound F-1 could be used to latent fingerprint imaging because of its aggregation-induced emission feature.