Synthesis of methyl 4′-O-methyl-β-d-cellobioside-13C12 from d-glucose-13C6. Part 2: Solid-state NMR studies

Double Quantum (DQ) NMR, which utilizes the magnetic dipole interaction between the 13C atoms, was used for the complete assignment of the 13C NMR resonances to the corresponding carbon ring positions for the monoclinic and triclinic allomorphs of methyl 4′-O-methyl-β-d-cellobioside-13C12(1-13C12), a cellodextrin model compound of cellulose 13C-perlabeled at the cellobiose core. The through-space interactions were used to identify the direct chemical bonds between adjacent carbon atoms in the rings. More importantly, the 13C NMR signals of the carbon sites C1′ and C4 involved in the glycosidic bond were identified. This allowed for the complete 13C chemical shift assignment, that when combined with the X-ray crystallography data provides a complete characterization.