Substitution on carbon or sulfer atom of derivatized polythiophenes

Abstract

This research studied the incorporation of substituents on thiophene and polythiophene derivatives. The reactions under investigation were bromination, acylation, S-arylation, and S-methylation. The acylation with acetyl chloride onto thiophene was found to give mostly unseparable and unidentifiable mixture. The 1H NMR spectrum of the mixture indicated some signals that could correspond to protons of acetyl group. The acetylation of polythiohene yielded insoluble brown solid, which could be characterized only by the presence of acetyl carbonyl peak in IR spectroscopy. The bromination using N-bromosuccinimide (NBS) obtained deep red liquid of 2,5-dibromothiophene. The bromination on polythiophene gave insloluble brown solid while the reaction on poly(3-hexylthiophene) successfully gave the 4-subsitututed product. The S-arylation through trapping of benzyne intermediate did not yield the products with all tested substrates. The S-arylation using diphenyliodonium salts on poly(3-hexylthiophene) obtained insoluble black solid with absorption at 700 nm. The S-methylation using methyl iodide on thiophene yielded the desired product verified by 1H-NMR spectroscopy.