Strategies towards functionalised electronically conducting organic copolymers

Here we describe the synthesis and electrochemical polymerisation of 2,5-di (2-thienyl)-3-(3-cyanopropyl)pyrrole, 2,5-di(2-thienyl)-3-(3-cyanopropyl)fu ran, and 3'-(3-cyanopropyl)-2,2':5',2 "-terthiophene. We report a synthetic methodology to these important conducting polymer precursor compounds that is facile, convenient and flexible. The key precursor to this study is the functionalised diketone 1,4-bis(2-thienyl)-2-(3-cyanopropyl)butane-1,4-dio ne. This molecule undergoes convenient ring closure to the terthiophene and dithienylpyrrole and dithienylfuran derivatives, all of which are, to our knowledge, new compounds. Importantly, this approach provides a flexible ro ute to a range of heterocyclic polymer precursors because the cyanoalkyl fu nctionality is grafted to the diketone before ring closure. Subsequently th e nitrile group provides synthetic utility either by reduction to the amine , or hydrolysis to the carboxylic acid. The new compounds described here un dergo electrochemical polymerisation leading to fixed ratio copolymers of f unctionalised pyrrole, thiophene and furan with thiophene itself. We descri be the characterisation of these polymers using FT-IR and X-ray photoelectr on spectroscopies.