A rhodamine-based fluorescent probe for Cu(II) determination in aqueous solution.

An 'off-on' rhodamine-based fluorescence probe for the selective detection of Cu(II) has been designed, exploiting the guest-induced structure transform mechanism. This system shows a sharp Cu(II)-selective fluorescence enhancement response in an aqueous system under physiological pH, and possesses high selectivity against a background of environmentally and biologically relevant metal ions. Under optimum conditions, the fluorescence intensity enhancement of this system is linearly proportional to the Cu(II) concentration from 50 nM to 6.0 μM with a detection limit of 29 nM.