Structural characterization and Zn²⁺-responsive properties of a carbazole schiff base: Fluorescence energy transfer-driven white-light emission and information encryption

A carbazole-based Schiff-base small molecule ( FG ) was developed, with its molecular structure characterized by 1 H NMR, 13 C NMR, HRMS-ESI, IR spectroscopy and DFT calculations to confirm the presence of key functional groups and spatial configuration. This compound exhibited remarkable fluorescence enhancement upon coordination with Zn 2+ , and the FG–Zn²⁺ complex efficiently transferred energy to four fluorophores—Rhodamine 6 G ( RH6G ), Eosin Y, Acridine Red, and Nile red. Notably, white-light emission was achieved at a 60:1 molar ratio of FG–Zn²⁺ to RH6G , with CIE coordinates (0.30, 0.34), close to the standard white-light point (0.33, 0.33). Additionally, FG can be mixed with polyvinyl alcohol ( PVA ) to form a writable gel that reveals hidden patterns under UV light, showing promise for information encryption and secure data storage.