Bisnaphthalimide-based fluorescent sensor for detecting alcohol and application in evaluating the liquors

Highlights: • The bisnapthalimide-based fluorescent material (bisNAP) was fabricated. • BisNAP showed enhanced emission in high polar medium via FRET process. • BisNAP can detect alcoholic strength in wide range. • BisNAP can discriminate the liquor products by naked-eye approach. -- Abstract: A fluorescent sensor (bisNAP) was designed to output the light-up signals in alcohols, which was used to detect alcoholic strength of distillate spirit. bisNAP was constructed according to the Först resonance energy transfer (FRET) process with two naphthalimide chromophores. A 4-phenylnapthalimide (NAPP), a bright emitter in wide range of polarity, was chose as the energy donor and a 4-imine naphthalimide (NAPI) was chose as the energy acceptor. The emission band of NAPP clearly overlapped with the absorption band of NAPI that met the maximum of energy transfer efficiency. The polarity-related experiments showed that the emission of bisNAP was enhanced in the high polar solvents, such as alcohols and DMSO. The fluorescent decay experiments were used to explore the nature of above inverse phenomenon. The SEM images were obtained from different solvents and the powder, which could further understand the interaction of fluorescent molecules surrounding by the solvent molecular cages with different polarity. Consideration of its high brightness in alcohols, the bisNAP was used in rapid detecting the alcoholic strength of the spirit products. Furthermore, this work provided an efficient strategy for designing the "turn on" sensors working in the high polar mediums in several fields.