title: A Thiophene-Containing Conductive Metallopolymer Using an Fe(II) Bis(terpyridine) Core for Electrochromic Materials.
abstract: Three Fe(II) bis(terpyridine)-based complexes with thiophene (Fe(L1)2), bithiophene (Fe(L2)2), and 3,4-ethylenedioxythiophene (Fe(L3)2) side chains were designed and synthesized for the purpose of providing two terminal active sites for electrochemical polymerization. The corresponding metallopolymers (poly-Fe(Ln)2, n = 2 or 3) were synthesized on indium tin oxide (ITO)-coated glass substrates via oxidative electropolymerization of the thiophene-substituted monomers and characterized using electrochemistry, X-ray photoelectron spectroscopy, UV-vis spectroscopy, and atomic force microscopy. The film poly-Fe(L2)2was further studied for electrochromic (EC) color-switching properties and fabricated into a solid-state EC device. Poly-Fe(L2)2films exhibit an intense MLCT absorption band at 596 nm (ε = 4.7 × 104M-1cm-1) in the UV-vis spectra without any applied voltage. Upon application of low potentials (between 1.1 and 0.4 V vs Fc+/Fc), the obtained electropolymerized film exhibited great contrast with a change of transmittance percentage (ΔT%) of 40% and a high coloration efficiency of 3823 cm2C-1with a switching time of 1 s. The film demonstrates commonplace stability and reversibility with a 10% loss in peak current intensity after 200 cyclic voltammetry cycles and almost no loss in change of transmittance (ΔT%) after 900 potential switches between 1.1 and 0.4 V (vs Fc+/Fc) with a time interval of 0.75 s. The electropolymerization of Fe(L2)2provides convenient and controllable film fabrication. Electrochromic behavior was also achieved in a solid-state device composed of a poly-Fe(L2)2film and a polymer-supported electrolyte sandwiched between two ITO-coated glass electrodes.
authors.affiliation: Department of Chemistry, The University of Texas at Austin , 105 E. 24th Street, Stop A5300, Austin, Texas 78712-1224, United States.
authors.forename: Yawei
authors.initials: Y
authors.lastname: Liang
authors.affiliation: Department of Chemistry, The University of Texas at Austin , 105 E. 24th Street, Stop A5300, Austin, Texas 78712-1224, United States.
authors.forename: Daniel
authors.initials: D
authors.lastname: Strohecker
authors.affiliation: Department of Chemistry, The University of Texas at Austin , 105 E. 24th Street, Stop A5300, Austin, Texas 78712-1224, United States.
authors.forename: Vincent
authors.initials: V
authors.lastname: Lynch
authors.forename: Bradley J
authors.initials: BJ
authors.lastname: Holliday
authors.affiliation: Department of Chemistry, The University of Texas at Austin , 105 E. 24th Street, Stop A5300, Austin, Texas 78712-1224, United States.
authors.forename: Richard A
authors.identifier: http://orcid.org/0000-0003-4174-6530
authors.initials: RA
authors.lastname: Jones
keywords: Fe bis(terpyridine) complexes; conducting metallopolymer; electrochemical polymerization; electrochromic device; electrochromic polymer