Characterization of d-glucaric acid using NMR, X-ray crystal structure, and mm3 molecular modeling analyses

d-Glucaric acid was characterized in solution by comparing NMR spectra from the isotopically unlabeled molecule with those from d-glucaric acid labeled with deuterium or carbon-13 atoms. The NMR studies provided unequivocal assignments for all carbon atoms and non-hydroxyl protons of the molecule. The crystal structure of d-glucaric acid was obtained by X-ray diffraction techniques and the structure was a close match to the low energy conformation generated from a Monte-Carlo-based searching protocol employing the mm3 molecular mechanics program. The molecule adopts a bent structure in both the crystalline and computationally generated lowest-energy structure, a conformation that is devoid of destabilizing eclipsed 1,3-hydroxyl interactions.

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► We employ NMR and X-ray diffraction techniques to characterize d-glucaric acid in aqueous solution and in the crystalline state, respectively.
► Molecular modeling analyses are employed to evaluate the conformational distribution of d-glucaric acid.
► 1H and 13C NMR assignments of d-glucaric acid are supported by spectral assignments from deuterium and carbon 13 labeled d-glucaric acid.
► Crystalline d-glucaric acid has a sickle conformation.
► The lowest energy computationally generated conformation of d-glucaric acid is a close match to its crystal structure.