CC bond enables difluorideboron β-diketonate derivatives with high contrast mechanoresponsive luminescence for reversible writing and information encryption†

Promoting the contrast of mechanoresponsive luminescent materials is of great significance in the application of information storage and encryption. In this work, two D–π–A difluorideboron β-diketonate derivatives were developed by varying the structure of the π-bridge. By incorporating a CC bond into the phenyl π-bridge of BF₂-PhCz, BF₂-PVCz with a phenyl vinyl π-unit achieved bathochromic fluorescence with a higher quantum yield and a higher contrast of mechanoresponsive luminescence (MRL). Theoretical calculations and experimental characterization revealed the CC bond contributed to the enhanced oscillator strength of the molecule and head-to-head molecular packing in the crystal. The applications of reversible writing and information deep-encryption were then realized based on the high-contrast and reversible MRL behavior of BF₂-PVCz.