Synthesis of novel Hg²⁺ receptors based on N-benzyloxyamide derivatives and their application to anion-selective electrodes

Novel Hg²⁺ receptors having two N-benzyloxyamide groups are synthesized, and their complexation ability toward metal cations is examined. The structure of the formed complexes was elucidated by ESI-MS and ¹H NMR spectroscopy. Deprotonation of the amide groups allows the receptors to form stable complexes with Hg²⁺. As an application of this neutral Hg²⁺ complex, an anion-selective electrode combined with a cationic additive is prepared, and exhibits an anti-Hofmeister selectivity pattern with enhanced selectivity for the iodide anion. The overall selectivity pattern of the electrode is I^- > ClO₄^- > SCN^- ≈ Br^- > salicylate^- > NO₂^- > Cl^- > NO₃^- ≫ HCO₃^- > SO₄^2- > F^- > H₂PO₄^-.