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Conformational studies of polymorphic N-octyl-D-gluconamide with N-15 (labeled) C-13 (natural abundance) REDOR spectroscopy

Sack, I. ; Macholl, S. ; Fuhrhop, J. H. ; Buntkowsky, G. (2000):
Conformational studies of polymorphic N-octyl-D-gluconamide with N-15 (labeled) C-13 (natural abundance) REDOR spectroscopy.
In: Physical Chemistry Chemical Physics, 2 (8), pp. 1781-1788. [Article]

Abstract

Magnetic dipolar couplings between the N-15 atom (labeled) and neighboring C-13 atoms (natural abundance) in three solid modifications of N-octyl-d-gluconamide are measured with rotational echo double resonance (REDOR). A unique spectral assignment of C-13 resonances is possible by means of their dipolar dephasing. While in the monolayer crystal and in the fiber modification the assignment is amenable to the solution spectra, in the bilayer crystallites a different assignment is found. The dipolar couplings in the range 45 to 1220 Hz are converted into CN distances. These distances are employed in conjunction with the C-13 chemical shieldings of the CP-MAS spectra to determine sets of possible torsion angles, which define the molecular conformation in the neighborhood of the amide group. In contrast to the monolayer crystal, for the fiber and bilayer crystallite modifications a gauche bend at the C2-C3 bond is found, giving the molecules the shape of a (2)G sickle.

Item Type: Article
Erschienen: 2000
Creators: Sack, I. ; Macholl, S. ; Fuhrhop, J. H. ; Buntkowsky, G.
Title: Conformational studies of polymorphic N-octyl-D-gluconamide with N-15 (labeled) C-13 (natural abundance) REDOR spectroscopy
Language: English
Abstract:

Magnetic dipolar couplings between the N-15 atom (labeled) and neighboring C-13 atoms (natural abundance) in three solid modifications of N-octyl-d-gluconamide are measured with rotational echo double resonance (REDOR). A unique spectral assignment of C-13 resonances is possible by means of their dipolar dephasing. While in the monolayer crystal and in the fiber modification the assignment is amenable to the solution spectra, in the bilayer crystallites a different assignment is found. The dipolar couplings in the range 45 to 1220 Hz are converted into CN distances. These distances are employed in conjunction with the C-13 chemical shieldings of the CP-MAS spectra to determine sets of possible torsion angles, which define the molecular conformation in the neighborhood of the amide group. In contrast to the monolayer crystal, for the fiber and bilayer crystallite modifications a gauche bend at the C2-C3 bond is found, giving the molecules the shape of a (2)G sickle.

Journal or Publication Title: Physical Chemistry Chemical Physics
Journal volume: 2
Number: 8
Uncontrolled Keywords: double-resonance nmr echo double-resonance rotational-echo amphiphilic properties amide linkages
Divisions: 07 Department of Chemistry
07 Department of Chemistry > Physical Chemistry
Date Deposited: 27 Oct 2014 20:48
Official URL: http://apps.webofknowledge.com/full_record.do?product=WOS&se...
Additional Information:

302QH Times Cited:17 Cited References Count:30

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