Structural analysis of polymers based on the origin of the NMR chemical shift

Abstract

The 13C chemical shifts of polyolefins were calculated by the combination of the fraction of the gauche conformation calculated on the basis of the Suter-Flory rotational isomeric state model and the 13C NMR γ-gauche effect semi-empirically. The interpretation of 13C NMR spectra is difficult by relying only on experimental data, but the chemical shift calculations make the interpretation easier and the peaks related to higher order stereoregularity could be assigned. The origin of the 1H chemical shift of proteins was also discussed on the basis of semi-empirical chemical shift calculation. The 13C chemical shift contour plots were used to determine the structure of Bombyx mori silk fibroin before spinning (Silk I) together with many other structural data obtained from several solid state NMR spectra.