New Schiff base chromophores composed of salicylaldehyde and naphthalimide derivatives for ion sensor application

New Schiff base chromophores with salicylaldehyde and naphthalimide structures were synthesized and characterized by using IR, 1H NMR, 13C NMR and HRMS. They all exhibited the obvious solid-state fluorescence features because of their inherent twisted structure, and some of them showed high selectivity and sensitivity for Mg2+ detection due to the dual contribution of excited-state intramolecular proton transfer and aggreation-induced emission effect. It was found that, for these new Schiff base chromophores, by adjusting the substituents with different electronic properties on the salicylaldehyde unit could fine-tuning their range of emission wavelengths and photophysical properties. Also, changing chain length based on -N-N=C- structure could influence their response to metal ions. The research results provided valuable information and thinking on the molecular design of novel fluorescence materials and related specific applications.