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

Abstract

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 CHCl3 solution under UV365nm irradiation, showed solvatochromic phenomena in solid film via CHCl3 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 Cu2+ in THF/water mixtures (v/v, 1:1) with the limit of detection (LOD) of 0.2 μM. Furthermore, the orange silica gel testing strip prepared by immersing silica gel plate in the photochromic CHCl3 solution, showed high-selectively fluorescent response toward Cu2+ (6 μM), which provided an effective strategy to detect metal ions.