Synthesis and Crystal Structure of Hg2+Complex with an S2O2Donor Dipodal Ligand. A Search for New Voltammetric Sensor for Hg2+

Abstract

Heavy metal complexations with host molecules have been received much attention, not only because of prime environmental concern, but also the heavy metal binding is one of fundamental problems of molecular recognition. Based on the optimal requirement of cooperative effect of the mixed coordinating sites via thiaoxa donor set for heavy metals, we have reported the solvent extraction, membrane transport and crystal structures of Ag and Pd complexes with the new system of the cyclic and acyclic ionophores incorporating a potential thiaoxa donor system. Particularly, the acyclic thiaoxa ionophores can be obtained simply and cheaply because there is no need for expensive and timeconsuming steps, such as high dilution or template methods, which is usually required in preparations of cyclic analogues. In the continuing work on the metal complexation, we were recently able to prepare the new Hg complex of the S2O2 dipodal ligand L and have determined its X-ray crystal structure. Although the stability constant for the Hg complex with L is not yet available, this result is enough to motivate the works on the stripping voltammetry by using the modified carbon paste electrode (CPE) as a more sophisticated detection procedure for Hg. Herein, we describe the preparation of the Hg complex of L together with its crystal structure. In addition, the characteristics of the L-modified CPEs are presented in terms of the Hg detection.