An Effective Selenium-Based Fluorescence Chemosensor for Selective Recognition of Hg2+ in Aqueous Medium: Experimental and Theoretical Studies.

We introduce a novel selenium-based compound [N-(Phenylcarbamoselenoyl) furan-2-carboxamide] for the optical and fluorimetric detection of Hg in an aqueous medium. The synthesized compound was characterized by different spectroscopic methods. The designed chemosensor FSU has shown a significant fluorescence quenching when Hg2+ ions were added to the sensing medium. Furthermore, Hg2+ ions provoked a 2:1 complex formation with the chemosensor FSU. It is found that the compound offers high selectivity over a variety of cations such as Co2+, Cr3+, Ni2+, Zn2+, Cu2+, Mg2+, Hg2+, Cd2+, Ca2+, Mn2+, Ga3+, Pb2+, Na+, Fe2+ and K+. The detection limit was calculated as 7.35 × 10-7 M. Also, FSU shows appreciable binding affinity towards Hg2+ ions with a binding constant value of 1.413 × 103 M-1. The ICT mechanism of mercury sensing was confirmed with spectroscopic techniques and DFT studies. Density functional theory was also implemented to investigate the structure of the Hg2+ complex and its electronic distribution in the aqueous medium. Finally, an MEP study was also carried out to obtain detailed information about the surface characteristics of the chemosensor FSU. Effectively, we have reported a potent chemosensor for Hg2+ in the aqueous medium.