POLY(ALKYL THIOPHENE-3-CARBOXYLATES) - SYNTHESIS AND CHARACTERIZATION OF POLYTHIOPHENES WITH A CARBONYL GROUP DIRECTLY ATTACHED TO THE RING

Polythiophenes with electron-withdrawing ester groups attached at the 3-position, namely poly(hexyl thiophene-3-carboxylate) (1a) and poly(octyl thiophene-3-carboxylate) (1b), have been synthesized using the Ullmann reaction with copper powder in DMF. Characterization of the polymers includes IR, H-1 and C-13 NMR, and UV-vis spectroscopy as well as TGA and molecular weight studies. The polymers also show red-orange and red fluorescence, respectively. The same polymers prepared using Ni(0) instead of Cu gave polymer with comparable molecular weights but higher polydispersity, which was not as uniform as shown by NMR spectroscopy and which had shorter conjugation lengths, as shown by blue-shifted UV-vis absorption and fluorescence maxima.