Towards understanding 13C-N.M.R. chemical shifts of carbohydrates in the solid state. The spectra of d-mannitol polymorphs and of dl-mannitol
1990; Elsevier BV; Volume: 197; Linguagem: Inglês
10.1016/0008-6215(90)84128-h
ISSN1873-426X
AutoresT. Bruce Grindley, Michael S. McKinnon, Roderick E. Wasylishen,
Tópico(s)Protein Structure and Dynamics
ResumoThe cross-polarization, magic-angle spinning 13C-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 13C-chemical shifts from the four species in the solid state were all less than the solution values. Conformations in deuterium oxide and di(2H3)methyl sulfoxide solutions were obtained from the vicinal proton coupling constants that resulted from analysis of the 1H-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 13C-chemical shifts are discussed.
Referência(s)