A new 1,2,3-triazole and its rhodamine B derivatives as a fluorescence probe for mercury ions.

A newly synthesized compound, 5-methyl-1-phenyl-1H-1,2,3-triazole-4- carboxylic acid (MPC) was analyzed for its quantum chemical parameters and theoretical spectrum by computational chemistry. The calculated spectrum was in accord with the experimental measurements in a great degree. Then MPC was successfully designed and synthesized to a novel rhodamine B derivative RMPC. The RMPC exhibited about a 4000-fold increase in fluorescence intensity in the presence of Hg2+ ions over most other competitive metal ions. The triazole appended colorless chemodosimeter RMPC turns to pink upon the complex formation only with Hg2+ ions as a 1: 2 M ratio and enables naked-eye detection. The coordination mechanism of turning on/off fluorescence for Hg2+ ions were well proposed by explaining Hg2+ inducing the ring-opened rhodamine B moiety. The fluorescence imaging experiments of Hg2+ in HeLa cell demonstrated that the probe was labeled and it could be used in biological systems.