Many structurally complex glycoconjugates take part in numerous biological processes, such as cell–cell interactions, cell–matrix interactions, etc. Some glycoconjugates may exhibit a complicated conformational equilibrium in solutions due to their structural arrangements.
The present analysis deals with the glycoconjugate constituted by two glucopyranoses (Glc) linked with quinazolinone structure. The structure of the investigated compound has been analysed by high-resolution NMR and DFT calculations in two solvents, dimethylsulfoxide (DMSO) and water. NMR data indicated that two stable forms are present in solution at room temperature in both solvents and that the difference in the conformational equilibrium is not considerably affected by the solvent. These two forms differ one another in geometry at the glycosidic linkages connecting the aromatic rings and the glucose residues. DFT calculations, at the ωB97XD/6-311++G(2d, 2p) level of theory and applying two solvent models (explicit and the smd), enabled detailed description of both forms present in solution. Theoretical data indicated that strong-hydrogen bond network stabilize these two distinct solution forms and that DFT-computed spin-spin coupling constants and NOEs agree well with the experimental data.