1,8-Naphthalimide-Cu(ІІ) ensemble based turn-on fluorescent probe for the detection of thiols in organic aqueous media.

A 1,8-naphthalimide-Cu(II) ensemble was rationally designed and synthesized as a new turn-on fluorescent probe utilizing the 'chemosensing ensemble' method for detections of thiols (Cys, Hcy and GSH) with high selectivity over other α-amino acids at pH 7.4 in organic aqueous media (EtOH/HEPES, v/v=9:1). The recognition mechanism was attributed to the remove Cu(II) from the 1,8-naphthalimide-Cu(II) ensemble by thiols and the release of flurescence of ligand 1. Remarkable fluorescence enhancements were therefore observed in the sensing process of thiols by the 1,8-naphthalimide-Cu(II) ensemble. Furthermore, the 1,8-naphthalimide-Cu(II) ensemble was successfully applied to the fluorescence imaging of thiols in CHO cells with high sensitivity and selectivity.