Metallopolymer electrochromic film prepared by oxidative electropolymerization of a Fe(II) complex with arylamine functionalized terpyridine ligand

• A chemistry–electrochemistry approach for synthesis of the D–A metallopolymer
• Non-diffusional redox process in the well-adhered polymer film
• With good stability, tunable thickness and granularly 3D morphology
• The anodic de-coloration behavior associated with Fe(III)/Fe(II) interconversion

The oxidative electropolymerization of [Fe(L)2](PF6)2 {L = 4′-{[p-(N-butyl-N-phenyl)amino]-phenyl}-2,2′:6′,2″-terpyridine} has been conducted by continuous cycling of the working electrode potential from 0 to 1.8 V in 0.1 mol·L− 1 Bu4NClO4/CH3CN solution containing 5.0 × 10− 4 mol·L− 1 monomer. The purple hybrid polymer film exhibits a non-diffusional charge transfer behavior of Fe(III)/Fe(II) couple and an irreversible redox process of phenylamine moiety on the Pt working electrode, as well as high stability in monomer-free electrolytic solution. The film thickness is easily tuned by controlling the number of potential sweeping cycle, and the AC impedance of as-formed film increases with cycling number. Morphological characterization of the film on indium tin oxide (ITO) has been provided by scan electron microscopy (SEM). The donor–acceptor (D–A) polymer film on ITO shows a broad and red-shifted 1MLCT wave in the UV–vis spectrum and a clearly electrochromic behavior from purple to pale yellow with the times of 1.1 s for the coloration step and 2.2 s for the bleaching step, the optical contrast of 20.3% and the coloration efficiency of 164 C− 1·cm2.

D–A metallopolymer film: The arylamine functionalized Fe(II)–terpyridine complex has been electrochemically deposited on ITO electrode to form a polymer film containing in-chain metal centers, which shows a clearly electrochromic behavior from purple to pale yellow.Figure optionsDownload as PowerPoint slide