TOWARDS UNDERSTANDING (13)C-N.M.R. CHEMICAL SHIFTS OF CARBOHYDRATES IN THE SOLID STATE. THE SPECTRA OF D-MANNITOL POLYMORPHS AND OF DL-MANNITOL

Article abstract of DOI:10.1016/0008-6215(90)84128-H

The cross-polarization, magic-angle spinning (13)C-n.m.r. spectra of solid DL-mannitol and of three polymorphs of D-mannitol have been recorded and assigned.Recrystallization of D-mannitol from several solvents under different conditions gave either one of the three known pure polymorphs or mixtures containing two or more of these polymorphs.The (13)C-chemical shifts from the four species in the solid state were all less than the solution values.Conformations in deuterium oxide and di((2)H3)methyl sulfoxide solutions were obtained from the vicinal proton coupling constants that resulted from analysis of the (1)H-n.m.r. spectra.The major cause of the differences between solid-state and solution chemical shifts is that there are significant populations of one of the gauche rotamers and the anti O-C-C-C rotamer about the terminal C-C bonds in solution.Other effects on solid-state (13)C-chemical shifts are discussed.