Synthesis and Properties of Cationic Polyelectrolyte with Regioregular Polyalkylthiophene Backbone and Ionic-Liquid Like Side Groups
Abstract
High-regioregular poly{3-[6-(1-methylimidazolium-3-yl)hexyl]thiophene-2,5-diyl bromide}, PMHT-Br, has been prepared by reaction of high-regioregular (above 92%) poly[3-(6-bromohexyl)thiophene-2,5-diyl] with 1-methylimidazole. PMHT-Br is soluble in water and water miscible solvents such as methanol, DMSO and shows solvatochromism; lambda(max) (nm): 423 (H2O); 435 (MeOH); 452 (DMSO).
Increased absorption band broadening observed for aqueous solution as well as NMR spectra in 020 suggests a micelle-like structure of PMHT-Br molecules in these solutions: poly(3-hexylthiophene) core and 1-methylimidazolium bromide shell. Despite the disturbing effect of ionic groups, the solid-state PMHT-Br shows absorption maximum at 520 nm, the band edge at 660 nm (ca. 1.9 eV), and fluorescence emission with maximum at 635 nm, in a good agreement with the polymer regioregularity.