2-(2′-Hydroxyphenyl)-4(3H)-quinazolinone derivatives based fluorescent probes for mercury(II) via an intramolecular proton transfer mechanism

2-(2′,5′-Dihydroxy-phenyl)-4(3H)-quinazolinone (DHPQ), a new fluorescent dye that exhibits excited state intramolecular proton transfer (ESIPT) reaction and possesses good photophysical properties, is synthesised and used as fluorescent probe for detection of Hg2+. Mercuric ions can be detected and quantitated by measuring the fluorescent intensity decrease of the probe. The decrease of fluorescence intensity of DHPQ upon the addition of Hg2+ was attributed to the blocking of ESIPT reactions of DHPQ and quenching its fluorescence. The analytical performance characteristics of the proposed Hg2+ probe were investigated. The probe can be applied to the quantification of Hg2+ with a concentration range covering from 8.0 × 10−7 to 2.0 × 10−4 mol L−1, with a working pH range of 5.5–6.5. It shows excellent selectivity for Hg2+ over other transition metal cations. The proposed method was testified for the Hg2+ assay in river water samples with satisfying recoveries.