A Novel Chemosensor Based on Rhodamine Derivative for Colorimetric and Fluorometric Detection of Cu in Aqueous Solution.

A new rhodamine-based reversible chemosensor ( 2) was synthesized, which exhibits high sensitivity and selectivity for Cu but no significant response toward other competitive metal ions in aqueous solution. Upon the addition of Cu, the spirolactam ring of 2 was opened and the solution color changed from colorless to red. Strangely, an unexpected fluorescence quenching was observed, which is contrary to the fluorescence turn-on of the most rhodamine-based chemosensors. The likely novel sensing mechanism has been proposed. [ABSTRACT FROM AUTHOR]