Regiochemistry and conformation of poly (3-hexylthiophene) via the synthesis and the spectroscopic characterization of the model configurational triads

The four model configurational triads of poly(3-hexylthmophene) (PHT) were synthesized by cross-coupling of the appropriate stannyl and bromo 3-hexylthiophene derivatives, catalyzed by Pd[(C6 H5)3P]4. The comparison of 1H and 13C NMR chemical shifts of the triads with those of PHT allows the unambiguous assignment of the regiochemistry of the polymer. The NMR data of the triads, in conjunction with the results of force field MMP2 calculations, also give information on the conformational properties of PHT samples of different regiochemistry.