A highly selective fluorescent probe for Cu2+ based on rhodamine B derivative

A new fluorescent probe I for Cu2+ based on a rhodamine B derivative was designed and synthesized. Probe 1 displays high sensitivity toward Cu2+ and about a 37-fold increase in fluorescence emission intensity is observed upon the addition of 10 equiv. Cu2+ in 50% water/ethanol buffered at pH 7.10. Besides, upon binding Cu2+ a remarkable color change from colorless to pink was easily observed by the naked eyes. The reversible dual chromo- and fluorogenic response toward Cu2+ is likely due to the chelation-induced ring-opening of rhodamine spirolactam. The linear response range covers a concentration range of Cu2+ from 8.0 x 10(-7) to 1.0 x 10(-4) mol/L and the detection limit is 3.0 x 10(-7) mol/L. Except Co2+, the probe exhibits high selectivity for Cu2+ over a large number of cations such as alkaline, alkaline earth and transitional metal ions. The accuracy and precision of the method were evaluated by the analysis of the standard reference material, copper in water (1.0 mol/L HNO3). The proposed probe has been used for direct measurement of Cu2+ content in river water samples and imaging of Cu2+ in living cells with satisfying results, which further demonstrates its value of practical applications in environmental and biological systems. (C) 2014 Elsevier B.V. All rights reserved.