title: Does intramolecular hydrogen bond play a key role in the stereochemistry of α- and β-D-glucose?
abstract: Four α- and three β-isomers of the d-glucose were optimized in gas phase using ab initio (MP2) and DFT (ωB97X-D) methods, both using the aug-cc-pVDZ basis set. While earlier works suggest that the orientation of the hydroxyl groups is due to intramolecular hydrogen bonds (H-bonds), the present study reveals that most H-bonds forming five-membered rings are either weak or even do not exist. The quantum theory of atoms in molecules (QTAIM) analysis showed only a few cases of H-bond in d-glucose, particularly for those H-bonds forming six-membered rings, while the non-covalent interactions (NCI) analysis indicated that most intramolecular H-bonds are not strong enough to justify the counter-clockwise arrangement of the OH⋯O chains. Natural bond orbital analysis supported the findings obtained from QTAIM and NCI analyses and indicated that the anomeric effect for d-glucose in the gas phase is governed by a balance of steric, electrostatic, and hyperconjugative interactions.
authors: Department of Chemistry, Federal University of Lavras, PO Box 3037, 37200-000 Lavras, MG, Brazil.
authors: Josué M
authors: JM
authors: Silla
authors: Chemistry Institute, State University of Campinas, PO Box 6154, 13083-970 Campinas, SP, Brazil.
authors: Rodrigo A
authors: RA
authors: Cormanich
authors: Chemistry Institute, State University of Campinas, PO Box 6154, 13083-970 Campinas, SP, Brazil.
authors: Roberto
authors: R
authors: Rittner
authors: Department of Chemistry, Federal University of Lavras, PO Box 3037, 37200-000 Lavras, MG, Brazil. Electronic address: matheus@dqi.ufla.br.
authors: Matheus P
authors: MP
authors: Freitas
mesh_terms: D005947:Glucose / Q000737:chemistry*; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008968:Molecular Conformation; D013237:Stereoisomerism; D013816:Thermodynamics
chemical_list: D005947:Glucose
keywords: Hydrogen bond; NBO; NCI; QTAIM; d-Glucose