Ferrocenylmethylthio-maleonitrile for selective recognition of Hg(II) ion

A new ferrocene based receptor 1,2-bis(ferrocenylmethylthio)-maleonitrile (FcMNT) was synthesized and characterized by elemental analysis, FTIR, NMR and X-ray single crystal diffraction. The ligand showed a high selection for Hg2+ in DMF or DMF/H2O mixed solution. Upon addition of Hg2+ in DMF, the receptor showed an obvious color change and significant UV–vis spectroscopic response. Electrochemical titrations revealed that the receptor sensed Hg2+ in high selectivity with an anodic shift of 307 mV. The 13CNMR titrations confirmed that the Hg2+ interacted with the S atoms of FcMNT when the amount of Hg2+ was under 1.0 equiv.; the Hg2+ interacted with CC and CN groups when the amount of Hg2+ was above 1.0 equiv.