Titre du document / Document title
DFT study of α-and β-D-allopyranose at the B3LYP/6-311++G** level of theory
Auteur(s) / Author(s)SCHNUPF Udo
WILLETT J. L.
BOSMA Wayne B.
MOMANY Frank A.
Résumé / Abstract
One hundred and two conformations of α- and β-D-allopyranose, the C-3 substituted epimer of glucopyranose, were geometry optimized using the density functional, B3LYP, and the basis set, 6-311++G**. Full geometry optimization was performed on different ring geometries and on the hydroxymethyl rotamers (gg/gt/tg). Analytically derived Hessians were used to calculate zero point energy, enthalpy, and entropy. The lowest energy and free energy conformation found is the α-tg(g-)-4
-c conformation, which is only slightly higher in electronic (∼0.2 kcal/mol) and free energy than the lowest energy α-D-glucopyranose. The in vacuo calculations showed a small (∼0.3 kcal/mol) energetic preference for the α- over the β-anomer for allopyranose in the 4
conformation, whereas in the 1
conformation a considerable (∼1.6 kcal/mol) energetic preference for the β- over the α-anomer for allopyranose was encountered. The results are compared to previous aldohexose calculations in vacuo. Boat and skew forms were found that remained stable upon gradient optimization although many starting boat conformations moved to other skew forms upon optimization. As found for glucose, mannose, and galactose the orientation and interaction of the hydroxyl groups make the most significant contributions to the conformation/energy relationship in vacuo. A comparison of different basis sets and density functionals is made in the Discussion section, confirming the appropriateness of the level of theory used here.
Revue / Journal TitleCarbohydrate research
Source / Source
2007, vol. 342, no
2, pp. 196-216 [21 page(s) (article)]
Langue / Language
Editeur / Publisher
Elsevier, Oxford, ROYAUME-UNI
Mots-clés d'auteur / Author Keywords
Localisation / Location
INIST-CNRS, Cote INIST : 12339, 35400015933170.0070
Nº notice refdoc (ud4) : 18458948