A Novel Fluorescent Sensor for Detecting Ag and Hg ions: A Combination of Theoretical and Experimental Studies.

A new fluorescent sensor based on diethylaminosalicylaldehyde-thiosemicarbazide (DST) was studied using a combination of density functional theory calculations and experimental investigations. DST was able to detect the metal ions Ag and Hg in the presence of various competing metal ions and anions, with detection limits of 0.45 and 0.34 µM, respectively. The DST sensor could operate in a fully aqueous environment and within a wide pH range from 5 to 9. Density functional theory studies supported the experimental findings in determining the stable structures of the DST sensor and the complexes between DST and the Ag and Hg ions, as well as elucidating the fluorescence ON-OFF mechanism in the DST sensor and the complexes.