Electropolymerization of Silver(I) Helicate into Conductive Metallopolymer: Structural and Functional Insights

A novel luminescent dinuclear helicate silver(I) complex has been synthesized via a complexation reaction with a N₄-donor ligand containing two triphenylamine (TPA) moieties. The structure of the complex has been confirmed by X-ray diffraction analysis and it revealed the presence of argentophilic interactions. The photophysical studies confirmed that ligand L, as well as the Ag(I) complex, is luminescent in the solid state. The Ag(I) complex exhibited a sharp emission band in the blue region from ligand molecules and broad emission band in the range 475 nm-700 nm assigned to ligand-to-metal charge transfer transition (LMCT) perturbed by the presence of argentophilic interactions. Both free ligand L and its Ag(I) complex undergo electropolymerization, leading to the formation of thin films. Moreover, electropolymerization of the Ag(I) complex occurred more easily compared with ligand L. The resulting polymer exhibited distinct spectroelectrochemical properties, enhanced stability, and 2-step color change from greenish yellow via orange to blue upon redox switching with fast coloration/bleaching times (2.7 s). These investigations demonstrate that the silver(I) helicate complex can serve as an effective electrochromic material and can be used in electrochromic devices. It was also shown that the presence of Ag(I) ions facilitates the formation of a thin layer of polymer on the electrode surface and improves the electrochromic performance of the polymer.