Fluorescent difference between two rhodamine-PAHs polystyrene solid-phase sensors for Hg(II) detection based on crystal structure and density functional theory calculation

Two novel rhodamine-polystyrene solid-phase fluorescence sensors PS-RB-2 and PS-R6G-2 with pyrene or naphthalene as fluorophore were synthesized for Hg(II) detection. Their structures were characterized by Fourier transform infrared (FTIR) spectra and scanning electron micrographs (SEM). Sensor PS-RB-2 displayed higher selectivity and sensitivity to Hg(II), with a lower detection limit of 0.065 μM. A detection mechanism involving the Hg(II) chelation-induced spirocycle open of rhodamine was proposed and discussed from theoretic level based on crystal structures and density functional theory (DFT) calculations. Sensor PS-RB-2 with recyclable and environment-friendly performance was successfully employed to fluorescent detection of Hg(II) in real water and fish samples, indicating its good potential in practical application. Its solid phase extraction columns were developed for rapid detection of Hg(II) by observing the color change with the naked eyes.