A new fluorescent probe of rhodamine B derivative for the detection of copper ion.

A new fluorescent probe, rhodamine B hydrazide oxalamide (RBHO), which shows very weak fluorescence, was synthesized, and its fluorescence could be substantially enhanced by the addition of copper ion. The probe shows a high selectivity and sensitivity to copper ion by forming a 1:1 complex in acetonitrile, and the chelating is reversible. Limit of detection for copper ion in acetonitrile was found to be 3.7x10(-8)mol L(-1). It was also found that copper ion could catalyze the hydrolysis of the probe in 50% (v/v) buffered (10mM Tris-HCl, pH 7.0) water/acetonitrile giving a highly fluorescent product, and the fluorescence detection of copper ion was developed in this neutral buffered media with a detection limit of 6.4x10(-7)mol L(-1). Determination of copper ion in water and synthetic samples in the presence of different interfering metal ions was successfully carried out with the new probe RBHO.