| Abstract
| - Topological analysis of the electron density profiles and the atomic basin integration data forthe most energetically favorable 4C1 and 1C4 conformers of β-d-glucopyranose, calculated at the B3LYP/6-31+G(d), MPWlPW91/6-311+G(2d,p), and MP2/6-31+G(d) levels, demonstrates that intramolecularhydrogen bonding between adjacent ring OH groups does not occur in glucopyranose, given the need todemonstrate a bond critical point (BCP) of correct (3,−1) topology for such an interaction to be termed ahydrogen bond. On the other hand, pyranose ring OH groups separated by three, rather than just two,carbon atoms are able to form an intramolecular hydrogen bond similar in topological properties andgeometry to that found for propane-1,3-diol. Vicinal, equatorial OH groups in the 4C1 conformer ofglucopyranose are, however, able to form strong bidentate hydrogen bonds with water molecules in acooperative manner, each water molecule acting simultaneously as both hydrogen bond donor and acceptor,and characterized by (3,−1) bond critical points with increased values for the electron density and theLaplacian of ρ(r) compared to an isolated ethane-1,2-diol/water complex.
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