Computational NMR of carbohydrates: 1. Glucopyranoses.

A high-level calculation of H and C NMR chemical shifts of α- and β-d-glucopyranoses is carried out at the DFT level with taking into account their conformational composition to reveal the most effective computational protocols. A number of dedicated DFT functionals in combination with Jensen's pcS-n (n = 0-4) family of basis sets were applied to evaluate the most reliable combination. It was found that BHandHLYP/pcS-2 provided the most accurate and reliable computational protocol. Based on the performed calculations, the established computational protocol is generally recommended for the calculation of H and C NMR chemical shifts of a wide series of carbohydrates.