A new rhodamine derivative (RhB-Im) was synthesized as an‘‘on-off’’chemosensor for Cu2þ in an
acidic aqueous solution. RhB-Im exhibited chemically reversible and highly selective and sensitive
fluorescence response toward Cu2þ in aqueous acetate-buffer/DMF solution (pH3.6)over other
competitive metal ions.Upon addition of Cu2þ, RhB-Im displayed remarkable fluorescence quenching
accompanied by a clear color change from pink to red. Based on the analysis of Stern–Volmer plots,a
static quenching mode was proposed to be primarily responsible for the fluorescence quenching event
when the concentration of Cu2þ was low,but,the energy-and electron-transfer processes can not be ruled out.