Photophysical and electrochemical properties of oligothiophene in non-polymeric and polymeric solvents

Effect of different solvents on emission behaviour of oligothiophene (OT) has been explored in this article. OT was synthesized using a modified cationic surfactant assisted polymerization technique. The average molecular weight was 1006 (which indicated an addition of 12 thiophene units) with a wider distribution (solid state crystallinity of 26% from X-ray crystallography). A gradient solubility of OT was obtained in N, N-dimethyl sulphoxide (95%), ethanol (82%) and chloroform (65%) due to descending solvochromatic interaction. A higher emission intensity (blue) and fluorescent quantum yield (11%) was obtained in DMSO than in ethanol (quantum yield 7%) due to a lower HOMO-LUMO transition energy. Conversely, excitation in a high molecular weight solvent like poly (vinyl alcohol) displayed a low emission intensity and fluorescent quantum yield (3%) despite lower HOMO-LUMO transition energy mainly due to quenching effect. Instead, such a system was suited for a capacitative action as demonstrated through cyclic voltametric measurement. (C) 2018 Elsevier B.V. All rights reserved.