Multicolored electrochromism of a poly{1,4-bis[2-(3,4-ethylenedioxy)thienyl]benzene} derivative bearing viologen functional groups

1,4-Bis[2-(3,4-ethylenedioxy)thienyl]-2,5-bis[6-(1'-butyl-4,4'-bipyridyl)hexyloxy]benzene tetrahexafluorophosphate (BEDOT-Ph-2V) was synthesized and electropolymerized to form a viologen bearing conductive polymer [P(BEDOTPh-2V)] film on an electrode surface. This polymer exhibits multicolor electrochronic behavior it is highly transparent light-blue P(BEDOT-Ph-1.7+-2V(2+)) at 1.0 V (vs Ag/Ag+), pale-bisque P(BEDOTPh0.6+-2V(2+)) at 0.1 V, magenta P(BEDOTPh0-2V(2+)) at -0.5 V, purple P(BEDOTPh0-2V(center dot+)) at -0.9 V, and crimson P(BEDOT0-2V(0)) at -1.4 V. Since both the viologen pendant and the polymer backbone have cathodic coloring characteristics and their redox-potential ranges do not overlap each other, the dual electrochromic action provides more plentiful electrochromic colors compared to simple poly(1,4-bis[2-(3,4-ethylenedioxy)thienyl]-2,5-dialkoxybenzene].