Synthesis of Fluorescence Chemodosimeters for Detection of Hg2+Based on Desulfurization of Thiocarbonyl Rhodamine B Derivatives and the Influence of Molecular Hydrogen Bond

Based on the irreversible desulfurization of thiocarbonyl promoted by mercury ions, two kinds of chemodosimeters of Rhodamine B derivatives as fluorescent probe respectively containing propylene acyl thiourea group and the propenyl thiourea group (RhBHA and RhBCH) were synthesized. They were used for the detection of Hg ions in aqueous solutions with high selectivity and high sensitivity. According to the fluorescence emission spectra and the colorimetric analysis under visible light, the influence of the chemical environment of thiocarbonyl groups on the desulfurization by mercury ions was studied. The results showed that there was no influence between the ring “open-close” transformation and the intramolecular hydrogen bond. The intramolecular hydrogen bonds increased the susceptibility of RhBHA toward desulfurization by mercury ions. With the molecular ring “open-close” transformation, the color change can be observed by the naked eye. In addition, we also studied the influence of the solvent intermolecular hydrogen bonding on the rate of desulfurization. By trace of the fluorescence intensity changes of RhBHA for Hg at different time interval, it was found that the formation of intermolecular hydrogen bond between the solvents and RhBHA could make the desulfurization rate slow-down.