A Rhodamine Derivative Based Chemosensor with High Selectivity and Quick Respond to Cr 3+ in Aqueous Solution.

In this paper, a new kind of colorimetric chemsensor aiming at detecting Cr3+ has been synthesized, and it is based on the "Off-On" effect of a rhodamine derivative. Comparing with other metal irons (Na+ , K+ , Ni2+ , Hg2+ , Fe3+ , Mn2+ , Co2+ , Cd2+ , Cu2+ , Pb2+ , Zn2+ , Mg2+ , Ba2+ , Ag+ , Fe2+ , Ce3+ ), the chemsensor has a quick and accurate response to Cr3+ in H2 O-EtOH solution (4/1, v/v). There is an obvious change in color, from colorless to bright pink when Cr3+ is detected. According to the fitting curve based on Benesi-Hildebrand equation and working curve of absorption strength in UV-vis spectrum, the binding pattern of Cr3+ and the rhodamine derivative follows a 1:1 stoichiometry. The chemsensor shows great potential in monitoring Cr3+ in the aqueous medium with high efficiency, which is supposed to complete the recognition in the minimum as 5.2 × 10-7  mol/L within 5 min.