Selective electrochemical recognition of ions in solution and at self-assembled monolayers

Quinone-functionalized calix[4]arenes having carboxylic acid groups or thio l groups were prepared and their spontaneous adsorption on silver and gold surfaces, respectively, was studied. Since the cavity-like structure of cal ixarenes was immobilized on the noble metal electrodes, they exhibited a se lective affinity towards specific hard metal ions in aqueous media. Voltamm etric and spectroscopic studies showed the well-ordered deposition of organ ic receptors and entrapment of metal ions. It also was found that the repea ted capture and removal of metal ions reversibly with chelating agents such as ethylenediaminetetraacetic acid (EDTA) was possible. This is the first example, to our knowledge, of voltammetric detection of hard metal ions in aqueous media using a chemically modified electrode with redox-active macro cyclic receptors. (C) 2001 Elsevier Science B.V. All rights reserved.