1H-13C NMR inverse detection of poly(3-hexylthiophene): characterization of the structural defects

NMR inverse detection was applied to the study of regiochemistry of a highly head to tail (HT)-regioregular poly(3-hexylthiophene) (PHT). It proved to be a valuable tool in the characterization of polymerization defects not directly revealable or assignable by inspection of the one-dimensional 13-C spectrum. Almost all the 13-C chemical shifts of the four configurational triads of PHT were derived by utilizing the aromatic protons, whereas through the alpha-protons of the aliphatic chain only carbons belonging to HT-HT connections were detected, owing to the high regiospecificity of the PHT under study and to the high multiplicity of aliphatic proton signals. The correctness of the model of the interpretation of PHT structure based on the four trimers of 3-hexylthiophene was confirmed.