A novel facilely prepared rhodamine-based Hg2+ fluorescent probe with three thiourea receptors

A novel rhodamine-based turn-on fluorescent probe with three thiourea receptors was designed, synthesized and fully characterized. In acetonitrile/4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid buffer (9/1, v/v, pH = 7.21), the probe showed high selectivity and sensitivity to Hg2+ with a 20-fold fluorescence enhancement at 583 nm. The increase in fluorescence intensity was linearly proportional to the concentration of Hg2+ in the range of 25-200 mu M with a detection limit of 3.04 x 10(-7) M. The probe could work in a nearly neutral pH span of 6.41-8.33 and exhibited excellent interference immunity. Real sample assay showed the probe had good practicability. The results from Job's plot, reversibility experiment, mass and infrared spectra analysis suggested a 1:3 probe/Hg2+ complex with an association constant of 9.88 x 10(11) M-3 and a new interaction way between the probe and Hg2+. (C) 2016 Elsevier Ltd. All rights reserved.