Chemistry Seminars

The Selective Recognition of Mercury (II) Ion by a 1,3-Dibenzimidazole Calixarene Derivative

Abstract: This paper describes calixarene molecules that can selectively recognize mercury (II) ion in an aqueous solution, and provide a way to measure the amount of Hg²⁺ present. Calixarene are a class of organic molecules that can bind small ions. With the attachment of chains containing functional groups to the rim of the calixarene, there is an increase in the selectivity towards a specific ion. This research determined that an amide-linked lower rim 1,3-dibenzimidazole derivative of calix[4]arene could selectively detect Hg²⁺ over eleven other divalent cations. To confirm the binding of Hg²⁺ to the calixarene derivative the researchers performed fluorescence titration, absorption spectral studies, ¹H NMR, and ESI MS. After determining the selective binding of Hg²⁺ to the calixarene derivative, the researcher used fluorescence titration to test five control molecule. The results from this study concluded that the entire synthesized ligand was necessary for the selective binding of the Hg²⁺. The researchers determined the ratio of ligand-Hg²⁺ to be 1:1 based on mole-ratios, a Job's plot and ESI MS. ¹H NMR spectroscopy was used to determine the Hg²⁺ binds to the benzimidazole portion of the calixarene derivative