A Facile Preparation of a New Water-Soluble Acridine Derivative and Application as a Turn-off Fluorescence Chemosensor for Selective Detection of Hg2+

A new acridine-based chemosensor was prepared, characterized and investigated for quantitative detection of Hg2+ ions in aqueous solutions. DFT and TD-DFT calculations showed that formation of a coordination bond between Hg2+ and the thiolate-sensor accounts for the fluorescence quenching, forming [HgLSCl2](2-) as the most stable species. Limit of detection and limit of quantification were as low as 4.40 and 14.7 mu mol L-1, respectively (R-2 = 0.9892, least squares method), and a linear concentration range of 14.7-100 mu mol L-1. Benesi-Hildebrand and Job formalisms are in accordance with the formation of a stable complex with a 1:1 (metal ion/sensor) ratio, and a determined binding constant of 5.14 x 10(3) L mol(-1). Robustness was verified based on the variation of several analytical conditions. In addition, the method presented maximum relative standard deviation of 4.6%, and recovery results was (90.3 +/- 4,6)% from distilled water, with no effect of interfering ions. Analytical figures of merit showed that the sensor can be an attractive low cost alternative for detection of Hg2+.