|French, Alfred - Al|
Submitted to: Journal of Carbohydrate Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/17/2001
Publication Date: 5/20/2002
Citation: Styron, S.D., French, A.D., Friedrich, J.D., Lake, C.H., Kiely, D.E. 2002. MM3(96) CONFORMATIONAL ANALYSIS OF D-GLUCARAMIDE AND X-RAY CRYSTAL STRUCTURES OF THREE D-GLUCARIC ACID DERIVATIVES - MODELS FOR SYNTHETIC POLY(ALKYLENE D-GLUCARAMIDES). Journal of Carbohydrate Chemistry. 21:27-51. Interpretive Summary: This work provides basic molecular shape properties for potential new, large-scale uses of agricultural materials, a nylon-like polymer. The molecules of long-chain glucaramides are not like most long agricultural molecules because the individual sugars do not take the ring forms usually found. Instead, the individual building blocks are said to be acyclic. There was little available information on the shapes of such carbohydrate-based molecules, so an extensive study was undertaken that involved both computerized prediction of the molecular shape and experimental determination by x-ray crystallography. They were also studied with Nuclear Magnetic Resonance Spectroscopy. Because there were no rings to help determine the molecular shapes, extensive calculations were needed for the computerized predictions. In all, 19,683 different molecular shapes were proposed and tested for the computerized prediction and the ones predicted to be most likely were essentially similar to the experimental structures. This information is of interest to scientists.
Technical Abstract: An exhaustive conformational analysis of D-glucaramide was carried out using MM3(96) [MM3(96). Molecular Mechanics Software used with permission from N.L. Allinger; University of Georgia]. Nine torsion angles were each driven in increments of 120 degrees, generating 19,683 starting conformations. Each conformation was then fully energy-minimized using MM3's block diagonal/full matrix optimization option at dielectric constants of both 3.5 and 6.5. Conformer populations were calculated based on the modeling results and calculated theoretical average 1H vicinal coupling constants were compared to experimental values obtained in D2O solution. Crystal structures of three acyclic D-glucaric acid derivatives (N.N -dimethyl-D-glucaramide, dispotassium D-glucarate, and sodium potassium D-glucarate) are reported. These structures and that of previously reported monopotassium glucarate correspond closely with model conformations that were within one kcal/mol of the global minimum.