Green-to-Black Electrochromic Copper(I)-Based Metallo-Supramolecular Polymer with a Perpendicularly Twisted Structure

A Cu(I)-based metallo-supramolecular polymer with a perpendicularly twisted structure was synthesized by a 1:1 complexation of tetrakis(acetonitrile)copper(I) triflate with the π-conjugated dibenzoeilatin ligand. Stepwise complexation behavior of Cu(I) with the ligand was revealed by titrimetric ultraviolet–visible (UV–vis) spectroscopic analysis. Formation of a high-molecular-weight polymer (Mw = 1.21 × 105 Da) was confirmed by a size-exclusion chromatography–viscometry–right-angle laser light scattering study. A bundle structure of the polymer chains was observed by scanning electron microscopy. A cyclic voltammogram of the polymer film showed reversible redox waves at a negative potential. A device consisting of indium tin oxide (ITO) glass coated with a film of the polymer exhibited reversible green-to-black electrochromism upon alternate application of −3 and +1 V.