|Bosma, Wayne - BRADLEY UNIV. CHEM. DEPT.|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: January 15, 2007
Publication Date: March 29, 2007
Citation: Momany, F.A., Willett, J.L., Bosma, W., Schnupf, U. 2007. DFT OPTIMIZATION STUDIES OF ALPHA-MALTOSE: ISO-ENERGETIC AND INTERNAL COORDINATE CONTOUR MAPS UPON ROTATION ABOUT THE GLYCOSIDIC BONDS. Meeting Abstract. xx. Technical Abstract: The disaccharide alpha-maltose is a molecular template for amylose. Our previous DFT work on maltose is expanded to a set of 63 fully optimized (B3LYP/6-311++G**) conformations. All clockwise, and counter clockwise hydroxyl groups, as well as 'kink' and band-slip conformers, are studied. Adiabatic iso-energetic difference maps were calculated (B3LYP/6-31+G*) at 5 deg C intervals around the (phi, psi) = (0,0) position, for many gg/gt/tg-r/c combinations. The results of the maps as well as geometry optimization studies show that the low energy conformations depends strongly on the direction taken by the hydroxyl bridging across the glycosidic bond. It was found that the energy landscape is very flat near the minimum on the iso-energetic contour maps. Deviations in selected internal coordinates as well as deviations in dipole moments are shown as phi-psi difference maps. The global energy minimum for alpha-maltose is a tg-gg-c conformer, with other conformations also of low energy.