Details

Autor(en) / Beteiligte

• Zhang, Wenhui
• Yoon, Mi-Kyung
• Meredith, Reagan J
• Zajicek, Jaroslav
• Oliver, Allen G
• Hadad, Matthew
• Frey, Michael H
• Carmichael, Ian
• Serianni, Anthony S

Titel

C-C spin-coupling constants in crystalline C-labeled saccharides: conformational effects interrogated by solid-state C NMR spectroscopy

Ist Teil von

• Physical chemistry chemical physics : PCCP, 2019-10, Vol.21 (42), p.23576-23588

Erscheinungsjahr

2019

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Solid-state 13 C NMR spectroscopy has been used in conjunction with selectively 13 C-labeled mono- and disaccharides to measure 13 C- 13 C spin-couplings ( J CC ) in crystalline samples. This experimental approach allows direct correlation of J CC values with specific molecular conformations since, in crystalline samples, molecular conformation is essentially static and can be determined by X-ray crystallography. J CC values measured in the solid-state in known molecular conformations can then be compared to corresponding J CC values calculated in the same conformations using density functional theory (DFT). The latter comparisons provide important validation of DFT-calculated J -couplings, which is not easily obtained by other approaches and is fundamental to obtaining reliable experiment-based conformational models from redundant J -couplings by MA ′ AT analysis. In this study, representative 1 J CC , 2 J CCC and 3 J COCC values were studied as either intra-residue couplings in the aldohexopyranosyl rings of monosaccharides or inter-residue (trans-glycoside) couplings in disaccharides. The results demonstrate that (a) accurate J CC values can be measured in crystalline saccharides that have been suitably labeled with 13 C, and (b) DFT-calculated J CC values compare favorably with those determined by solid-state 13 C NMR when molecular conformation is a constant in both determinations. Solid-state 13 C NMR reveals differences in O -glycosidic linkage conformation in solution and in crystalline disaccharides. Experimental J CC values in crystalline samples provide a means of validating J CC calculated from density functional theory.