Synthesis and Electrochromic Properties of Star-Shaped Oligomers with Phenyl Cores.

A series of star-shaped conjugated oligomers, 1,3,5-tri(2'-thienyl) benzene (3TB), 1,3,5-tri(3',4'-ethylenedioxythienyl) benzene (3EB), 1,3,5-tri[5',2"-(3",4"-ethylenedioxy-thienyl)-2'-thienyl] benzene (3ETB), and 1,3,5-tri[5',2"-(3",4"-ethylenedioxy-thienyl)-2'-thienyl]-4-(3',4'-ethylenedioxythienyl)benzene (3TB-4EDOT), were synthesized. The star-shaped polymer, poly(1,3,5-tri[5',2"-(3",4"-ethylenedioxythineyl)-2'-thienyl]benzene) (P3ETB), was also prepared. The electrochemical and electrochromic properties of these conjugated oligomers and polymer were investigated. These oligomer and polymer films showed reversible, clear color changes upon electrochemical doping and dedoping. The color of the P3ETB film reversibly changed from orange to blue under doping and dedoping. The switching times for doping and dedoping were 1.2 and 0.9 s, respectively.