Preparation of poly(2,6-quinoxaline)s having alkyl groups and their optical and electrochemical properties

Abstract

Poly(2,6-quinoxaline)s having methyl (P(2,6-Qx(Me)) and ethyl (P(2,6-Qx(Et)) substituents in 3-position have been prepared by organometallic dehalogenation polycondensation of the corresponding dichloro monomers in high yields. P(2,6-Qx(Et)) gives an [η] value of 3.38 dl g -1 . These polymers exhibit π-π * absorption peaks at a longer wavelength by above 20 nm compared with that of non-substituted P(2,6-Qx). Films of the polymers give rise to an electrochemically active cycle in the reduction region in an acetonitrile solution, and they show a reduction (n-doping) peak in the range of -1.83 through -2.03 V vs. Ag/Ag + . The n-doping levels of P(2,6-Qx(Me)) and P(2,6-Qx(Et)) are 0.33 and 0.28, respectively. The electrochemical n-doping of the film of P(2,6-Qx(Et)) is accompanied by changes in its UV-vis spectrum (electrochromism), and new absorption peaks emerge in the range of 504 to 793 nm by the n-doping. The polymers are also electrochemically active in acidic aqueous media.