Ex-situ study by X-ray absorption near-edge spectroscopy of the topography of complexing cavities immobilized in an electronically conducting polymer

In this paper we have undertaken an ex-situ X-ray absorption near-edge spectroscopic (XANES) study of electrodes modified (ME) by polypyrrole films containing the metallic ions Cu(I) or Co(II), chelated, in each case, by two dpp units (dpp = 2,9-diphenyl-1,10-phenanthroline) immobilized in the polypyrrole matrix. From these XANES studies, we have evaluated the topography of the complexing cavities as a function of the oxidation state of the metallic centres which is modulated ex-situ electrochemically. The spectroscopic results obtained show that the potential topographic changes of the ligand set are strongly dependent on the number of covalent links between the coordinating core and the polypyrrole matrix. If the complexing cavities are strongly connected to the polymer network, any modifications of their topography and of the oxidation state of the metallic ions are observed after the ex-situ electrochemical polarization. (C) 1998 Elsevier Science S.A. All rights reserved.