H-1 and C-13 NMR study of regioregular head-to-tail oligo(octylthiophene)sand poly(octylthiophene)

The H-1 and C-13 signals of the aromatic region of monodisperse regioregula r head-to-tail (HT) oligo(octylthiophene)s ranging from the dimer to the he xamer were assigned in CDCl3 and THF-d(8). The linear dependence of proton chemical shifts on the reciprocal number of thiophenes was demonstrated in both solvents. Weak signals surrounding the main peak in the spectrum of th e regioregular HT poly(octylthiophene) were assigned in CDCl3 and THF-d(8) in the light of results obtained for the hexamer. In particular, the end of chain protons of the polymer could be assigned. Spin-lattice relaxation ti mes (T-1) of aromatic protons of the hexamer were measured in CDCl3 and THF -d(8). We observed that T-1 depended on the position of the proton along th e main chain. This result was interpreted in terms of molecular motions. Co pyright (C) 2001 John Wiley & Sons, Ltd.