A novel Schiff's base conjugate with multicolor changes in multiple states and its multipurpose applications for selective detection of Cu2+ in aggregated state and on silica gel strip

Herein, a pair of Schiff's base conjugates were developed by embellishing benzil hydrazone with 4-dimethylaminobenzaldehyde and 4-(diethylamino)salicylaldehyde, respectively. Particularly, 4-(diethylamino)salicylaldehyde-functionalized Schiff's base featured multicolor changes in multiple states (solution, solid film and aggregation states). To be specific, it displayed the excellent photochromic property in CHCl 3 solution under UV 365nm irradiation, showed solvatochromic phenomena in solid film via CHCl 3 or EtOH solvents/vapours, and exhibited bicolor emission (yellow to cyan) from aggregation-induced emission (AIE) characteristic to aggregation-induced quenching (ACQ) effect in THF/water system. Moreover, it served as a fluorescent probe for sensing Cu 2+ in THF/water mixtures (v/v, 1:1) with the limit of detection (LOD) of 0.2 μ M. Furthermore, the orange silica gel testing strip prepared by immersing silica gel plate in the photochromic CHCl 3 solution, showed high-selectively fluorescent response toward Cu 2+ (6 μ M), which provided an effective strategy to detect metal ions. • A novel Schiff's base conjugate exhibited the photochromism in CHCl 3 solution under UV 365nm irradiation. • The solvatochromic switch was observed in solid film via CHCl 3 or EtOH solvents/vapours. • The bicolor luminescence presented with increasing proportion of water in aggregated process. • Applications for real-time and visual monitoring Cu 2+ .