A theoretical study of α- and β-d-glucopyranose conformations by the density functional theory

A theoretical investigation of stable conformations of d-glucopyranose was carried out using the density functional theory (DFT). Solvation effects were also evaluated with polarization continuum model (PCM) calculations. The 6-311++G(2d,2p) basis sets were appropriate. The estimated populations of gg, gt, and tg hydroxylmethyl rotamers were 53, 46, and 1 for α-d-glucopyranose and 48, 51, and 1 for β-d-glucopyranose. Estimated ratios of α- to β-anomers were 26 and 74, respectively. These populations are in good agreement with the NMR experiments. The first calculations of the vibrational circular dichroism (VCD) spectra of d-glucopyranose were also performed.