An ESIPT fluorescent dye based on HBI with high quantum yield and large Stokes shift for selective detection of Cys.

We report 3-(4,5-diphenyl-1H-imidazol-2-yl)naphthalen-2-ol (DPIN) as an interesting luminescent material displaying ESIPT with a large Stokes shift of ∼180 nm even in protic/polar solvents. Stable homo-dispersed nanoparticles formed by inter- and intramolecular H-bonds in aqueous media and the corresponding aggregation induced enhanced emission with a high quantum yield up to 0.45 were observed. Factors such as pH value and ions (cations and anions) showed a negligible effect on the fluorescence performance. A probe of 3-(4,5-diphenyl-1H-imidazol-2-yl)naphthalen-2-yl-acrylate (DPIN-A) based on this molecule was designed. The results revealed that it can be used for sensing of Cys with high selectivity and sensitivity.