A Novel Fluorescent Sensor for Detecting Ag⁺ and Hg²⁺ 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 Hg²⁺ 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 Hg²⁺ ions, as well as elucidating the fluorescence ON-OFF mechanism in the DST sensor and the complexes.