Near-IR electrochromism of the electropolymerization film prepared from a cyclometalated dinuclear Pt(II) complex

The cyclometalated dinuclear platinum acetylide with a 9,9-dioctylfluorene spacer and two terminal triphenylamine groups has been successfully synthesized and characterized by 1H NMR, 13C NMR and MALDI-TOF MS. The active triphenylamine groups efficiently trigger the oxidative electropolymerization process to form a reddish-orange film on the working Pt and ITO electrodes by cyclic voltammetry. The compact film shows a polyaniline-like AC impedance behavior and an inverse dependence of AC impedance on its thickness. As a result of switching of the MLCT/ICT and dication absorption transitions between 0 and +1.8 V, this metallopolymer film exhibits the near-IR electrochromism with significant optical contrast ratio (ΔT%=78.3% at λ=775nm), comparative response time (3.8s for the coloration step and 11.0s for the bleaching step) and high anodic coloration efficiency (CE=208.3C−1·cm2).