Secondary isotope multiplet NMR spectroscopy of partially labeled entities. Carbon-13 SIMPLE NMR of carbohydrates

Christofides, John C.; Davies, David B.

doi:10.1021/ja00353a040

Cited by 99 publications

(69 citation statements)

References 4 publications

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“…Among them, HO(2c) of T-x-x are most sensitive (Dd(OH)/DT between À 7.1 and À 7.4 ppb/K) and slightly more so than HO(2c) of T-x (Dd(OH)/DT between À 6.7 and À 6.8 ppb/K). This agrees with the weakly persistent interchain O(6c)ÀH´´´O(2c*) H-bond that will enhance the acidity of HO(2c) of T-x-x, and thereby the interaction with (D 6 SIMPLE 1 H-NMR Experiments [41] allow to detect strongly persistent intramolecular H-bonds between OH groups (see [39] [42] and refs. cit.…”

supporting

confidence: 71%

Oligosaccharide Analogues of Polysaccharides, Part 20 , NMR Analysis of Templated Cellodextrins Possessing Two Parallel Chains: A Mimic for Cellulose I?

Bernet

Vasella

2000

HCA

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Für Albert, den Meister des Komplexen an sich Naphthalene-1-ethanol and naphthalene-1,8-diethanol carrying one or two glycosidically bonded cellodextrin chains, T-x and T-x-x, resp. (x 1 ± 4, 8) were analyzed by NMR spectroscopy. For solutions in (D 6 )DMSO and (D 5 )pyridine, analysis was based on a comparison of chemical shifts, coupling constants, temperature dependence of OH signals, and ROESY spectra of the singly and doubly substituted T-x and T-x-x. The characteristic strong intrachain inter-residue O(3)ÀH´´´O(5') H-bond of celluloses was detected in the singly and doubly substituted naphthalenes. Also detected was a weakly persistent flip-flop H-bond between HO(2') and HO(6). Weak interchain interactions were, however, observed only for the units closest to the link of T-x-x in (D 6 )DMSO and for parallel units of T-1-1 and T-3-3 in (D 5 )pyridine. Interchain interactions in T-x-x are stronger in (D 5 )pyridine than in (D 6 )DMSO and decrease with increasing distance from the link. The solidstate CP/MAS 13 C-NMR spectra of T-x-x were compared with those of T-x and of celluloses. The spectrum of T-8 and, surprisingly, also of T-8-8 strongly resembles that of cellulose II and not that of cellulose I b , evidencing that a flexible template possessing parallel cellodextrin chains does not impose sufficient constraints on the structure of supramolecular assemblies to mimic cellulose I b , but leads to a valuable mimic of cellulose II.Introduction. ± There are at least four polymorphs of celluloses, namely cellulose I ± IV [2 ± 4]. The two most common polymorphs are cellulose I, the native form, and cellulose II, the mercerised or regenerated form. Cellulose II is the most stable polymorph. There are two allomorphs of cellulose I. Cellulose I a predominates in algal celluloses [5] [6] and cellulose I b in plant celluloses. Cellulose I b is more stable than cellulose I a [7]. Common to all celluloses is the 4 C 1 conformation of all 1,4-linked b-dglucopyranosyl moieties and the intrachain inter-residue O(3)ÀH´´´O(5') H-bond 2 ). Alternating glucopyranosyl units are rotated by ca. 1808 relative to each other; thus, cellobiosyl moieties are the repeating unit of celluloses. Current three-dimensional structures of celluloses are mainly based on limited X-ray-diffraction data of polycrystalline samples (a few tens of reflections) and computer modeling. Additional models for cellulose II are derived from the crystal structure of b-cellotetraose hemihydrate and from a neutron-diffraction analysis of deuteriated cellulose II fibres (see below).

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confidence: 71%

Oligosaccharide Analogues of Polysaccharides, Part 20 , NMR Analysis of Templated Cellodextrins Possessing Two Parallel Chains: A Mimic for Cellulose I?

Bernet

Vasella

2000

HCA

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“…Another method for confirming that the two carbon resonance signals crossed and also to unambiguously assign them is to use H/D isotope effects (23)(24)(25). It has been demonstrated (25) that carbons directly bonded to an amino group (that is, a two-bond isotope effect) experience a low frequency shift of approximately 0.055-0.097 ppm/deuteron while carbons two bonds from an amino group (a three-bond isotope effect) experience a low frequency shift of approximately 0.025-0.051 ppm/deuteron.…”

Section: Assignment Of 13c and 'H Resonances Of The P-alanyl Groupmentioning

confidence: 99%

A ¹H and ¹³C nuclear magnetic resonance study of carnosine

Friedrich¹,

Wasylishen²

1986

Can. J. Chem.

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The proton and carbon-13 resonance signals of carnosine (β-alanyl-L-histidine) were unambiguously assigned using a variety of nmr techniques including proton–carbon chemical shift correlations, titrations of nmr chemical shifts, coupling constants, and isotope shifts. From the 13C nmr titration, carnosine's three pKa values were estimated to be 2.7, 7.1, and 10.6, and it was found that the imidazole ring existed predominantly as the 3-H tautomer in basic solution. Conformational information about the Cα—Cβ bond and about the N—Cα bond was deduced from observed 3J(C,H) and 3J(H,H) values. The 13C nmr spectrum of carnosine in solution is also compared with that obtained for a solid sample.

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“…Moreover, most of the published data available are contradictory. [3][4][5][6][7][8][9][10][11][12] Part of the published data is from selectively protected sugars, for example, sugars methylated at the anomeric center to hinder mutarotation and so enabling assignment of the a-and b-anomerically pure saccharides separately with less overlapping signals. The 13 C chemical shifts of some anomerically locked glucosyl glucosides have been determined using dynamic NMR, and they have also been compared with those of the monomer D D-glucose.…”

Section: Introductionmentioning

confidence: 99%

Complete assignments of the 1H and 13C chemical shifts and JH,H coupling constants in NMR spectra of d-glucopyranose and all d-glucopyranosyl-d-glucopyranosides

Roslund

Tähtinen

Niemitz

et al. 2008

Carbohydrate Research

209

119

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Secondary isotope multiplet NMR spectroscopy of partially labeled entities. Carbon-13 SIMPLE NMR of carbohydrates

Cited by 99 publications

References 4 publications

Oligosaccharide Analogues of Polysaccharides, Part 20 , NMR Analysis of Templated Cellodextrins Possessing Two Parallel Chains: A Mimic for Cellulose I?

Oligosaccharide Analogues of Polysaccharides, Part 20 , NMR Analysis of Templated Cellodextrins Possessing Two Parallel Chains: A Mimic for Cellulose I?

A ¹H and ¹³C nuclear magnetic resonance study of carnosine

Complete assignments of the 1H and 13C chemical shifts and JH,H coupling constants in NMR spectra of d-glucopyranose and all d-glucopyranosyl-d-glucopyranosides

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Secondary isotope multiplet NMR spectroscopy of partially labeled entities. Carbon-13 SIMPLE NMR of carbohydrates

Cited by 99 publications

References 4 publications

Oligosaccharide Analogues of Polysaccharides, Part 20 , NMR Analysis of Templated Cellodextrins Possessing Two Parallel Chains: A Mimic for Cellulose I?

Oligosaccharide Analogues of Polysaccharides, Part 20 , NMR Analysis of Templated Cellodextrins Possessing Two Parallel Chains: A Mimic for Cellulose I?

A 1H and 13C nuclear magnetic resonance study of carnosine

Complete assignments of the 1H and 13C chemical shifts and JH,H coupling constants in NMR spectra of d-glucopyranose and all d-glucopyranosyl-d-glucopyranosides

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A ¹H and ¹³C nuclear magnetic resonance study of carnosine