Secondary isotope multiplet NMR spectroscopy of partially labeled entities. Carbon-13 SIMPLE NMR of carbohydrates
/sup 13/C NMR measurements have been made in dimethylsulfoxide-d/sub 6/ solutions of some carbohydrates (methyl ..cap alpha..-D-gluco- and galactopyranosides, melibiose, maltose, and ..beta..-cyclodextrin) in which exchangeable protons have been partially deuterated. Signals from single carbon atoms are observed as a series of multiplets (singlets to octets) with intensity ratios that vary quantitatively with OH:OD ratios. Partial deuteration of exchangeable protons in molecules permits direct observation of the different isotopomers measured under conditions of slow exchange and the resonance line separations can be analyzed in terms of the two-bond (..beta..) and three-bond (..gamma..) istope effects that contribute to the deuterium-induced secondary isotope shift. Magnitudes of ..beta.. and ..gamma.. effects are found to vary with configuration of carbon atoms, and substitution and hydrogen bonding of hydroxyl groups. Signal multiplets and magnitudes of isotope effects are used to assign the spectra of carbohydrates as shown for both ..cap alpha..- and ..beta..-forms of the ..cap alpha..1-..-->..6-linked (melibiose) and ..cap alpha..1..-->..4-linked (maltose) reducing disaccharides. The method also confirms the presence and direction of intramolecular hydrogen bonding in ..cap alpha..1..-->..4 glucosides (i.e., C2'-O2'...H-O-C3) by observation of an isotope effect on C2' transmitted through a hydrogen bond. Measurements by NMR spectroscopy of secondary isotope multiplets of partially labeled entities (SIMPLE NMR) have widespread application for signal assignment and for studying isotope effects in molecules. 5 figures, 4 tables.
- Research Organization:
- Birkbeck Coll., London, England
- OSTI ID:
- 5614563
- Journal Information:
- J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 105:15; ISSN JACSA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400301 -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
400302 -- Organic Chemistry-- Isotope Effects-- (-1987)
400303* -- Organic Chemistry-- Isotope Exchange & Isotope Separation-- (-1987)
CARBOHYDRATES
DATA
DEUTERIUM
EXPERIMENTAL DATA
HYDROGEN ISOTOPES
INFORMATION
ISOTOPE EFFECTS
ISOTOPES
ISOTOPIC EXCHANGE
LABELLING
LIGHT NUCLEI
MAGNETIC RESONANCE
NUCLEAR MAGNETIC RESONANCE
NUCLEI
NUMERICAL DATA
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
RESONANCE
SPECTRAL SHIFT
STABLE ISOTOPES
STRUCTURAL CHEMICAL ANALYSIS