Three Multifunctional Difluoroboron Fluorescent Dyes with Five Member N-Heterocyclic Ring for Mechanofluorochromic Behaviors, the Ink-Free Writing and Latent Fingerprints Imaging

Abstract

To further develop multifunctional fluorescent dyes, three difluoroboron compounds (F-1, F-2, and F-3) containing five member N-heterocyclic ring groups acting as the electron-withdrawing units were synthesized. It was found that compounds F-1 with 1,2,4-trizole segment and F-3 with 1,2,3-trizole portion displayed aggregation-induced emission activities, which was endowed with latent fingerprints imaging. But compound F-2 with pyrazole unit exhibited aggregation-caused quenching phenomenon. Meanwhile, three compounds possessed mechanofluorochromic behaviors, among them, the emission spectra of compound F-1 only about 5 nm shift after grinding, compounds F-2 was red-shifted from 475 to 501 nm, compound F-3 was red-shifted from 482 to 507 nm. And compounds F-2 and F-3 could be used in ink-free writing, nevertheless, the prepared safety paper by compound F-2 was once-only use due to its irreversible mechanofluorochromic behavior, that of compound F-3 was rewritable owing to reversible mechanofluorochromic behavior. It provided a foundation for exploration multifunctional difluoroboron compound with 1,2,3-trizole moiety.

Keywords: difluoroboron compounds, five member N-heterocyclic ring, mechanofluorochromic, aggregation-induced emission, ink-free writing, latent fingerprints imaging