A rhodamine B-based “turn-on” fluorescent sensor for detecting Cu2+ and sulfur anions in aqueous media

Abstract

A novel selective fluorescent chemosensor L based on rhodamine B derivative has been designed and synthesized to optically detect Cu2+ and S2− in aqueous buffer solution. The fluorescence of L was excited by Cu2+ with a 1 : 1 binding ratio, and could be used as a “turn-on” type sensor. Otherwise, the emission band would undergo a slight red-shift. Once binding with Cu2+, the copper complex can exhibit high selectivity for S2−. Upon addition of Cu2+, the color of the chemosensor L changes from colorless to pink. Additionally, the resulting pink solution changes to colorless immediately upon the addition of S2−. However, no phenomenon change could be observed in the presence of other anions. Conclusively, the color changes suggest that sensor L could serve as a “naked-eye” sensor for Cu2+ and S2−.