A highly efficient and selective turn-on fluorescent sensor for Hg2+, Ag+ and Ag nanoparticles based on a coumarin dithioate derivative.

Based on chelation-enhanced fluorescence, a new fluorescent coumarin derivative probe 3(1-(7-hydroxy-4-methylcoumarin)ethylidene)hydrazinecarbodithioate for Hg(2+), Ag(+) and Ag nanoparticles is reported. Fluorescent probe acts as a rapid and highly selective "off-on" fluorescent probe and fluorescence enhancement by factors 5 to 12 times was observed upon selective complexation with Hg(2+), Ag(+) and Ag nanoparticles. The molar ratio plots indicated the formation of 1:1 complexes between Hg(2+) and Ag(+) with the probe. The linear response range covers a concentration range 0.1 × 10(-5) -1.9 × 10(-5) mol/L, 0.1 × 10(-5) -2.3 × 10(-5) mol/L and 0.146 × 10(-12) -2.63 × 10(-12) mol/L for Hg(2+), Ag(+) and Ag nanoparticles, respectively. The interference effect of some anions and cations was also tested.