Formation of an emissive telluroxide promoted by Hg2+ in aqueous environment: A new naked-eye and ratiometric rhodamine dimer fluorescent mercury(II) probe

摘要

A new chemosensor based on tellurium-rhodamine B (TRB) for the fast and selective detection of Hg2+ in aqueous medium was designed and synthetized in only two steps from a symmetrical organic telluride and rhodamine B. The structure of TRB was determined by RMN, HRMS and IR and its photophysical properties were determined in MeCN/H2O 75:25 v/v. TRB is able to detect Hg2+ in solutions diluted until 1.71 mu mol/L and containing until 75% of water in it. In the presence of Hg2+, TRB presents an intense pink color with maximum absorption in 558 nm (log epsilon = 4.93) and a strong fluorescence emission with maximum intensity in 582 nm (Phi = 0.17). The detection of Hg2+ by TRB occurs by the oxidation of the tellurium promoted by Hg2+, where a redox mechanism was proposed. Even the detection of Hg2+ occurring by the oxidation of tellurium, TRB presented a high selectivity for Hg2+, even when several ROS (H2O2, KNO2, NaOCl, NaONOO e KO2) were submitted to the screening.