Nematic phase nuclear magnetic resonance studies of the molecular structures of cyclobutanone and methylenecyclobutane

1976 ◽  
Vol 54 (4) ◽  
pp. 657-664 ◽  
Author(s):  
K. C. Cole ◽  
D. F. R. Gilson
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nematic Phase ◽  
Proton Magnetic Resonance ◽  
Molecular Structures ◽  
Coupling Constants ◽  
Magnetic Resonance Studies ◽  
Dipole Coupling ◽  
Nmr Data ◽  
Ring Puckering

The nematic phase proton magnetic resonance spectra of cyclobutanone and methylenecyclobutane have been analyzed and the direct dipole coupling constants corrected for the averaging effects of the ring puckering vibrations. The nmr data have been used in conjunction with microwave spectroscopic results to derive the molecular structures.

Nematic phase nuclear magnetic resonance studies of the structure and orientation of 1,5- and 2,6-naphthyridines

1976 ◽  
Vol 54 (17) ◽  
pp. 2783-2787 ◽  
Author(s):  
Y. P. Lee ◽  
D. F. R. Gilson
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Hydrogen Bond ◽  
Liquid Crystal ◽  
Magnetic Resonance ◽  
Nitrogen Atom ◽  
Nematic Phase ◽  
Proton Magnetic Resonance ◽  
Magnetic Resonance Studies ◽  
Molecular Dimension ◽  
Skeleton Structure

The proton magnetic resonance spectra of 1,5- and 2,6-naphthyridine dissolved in the nematic liquid crystal MBBA have been analysed. The proton geometries do not give good fits to the ring skeleton structure but it appears that the carbon–hydrogen bond lengths are not all of equal length and the bond angles indicate some bending of the C—H bonds toward the adjacent nitrogen atom. The probability functions for orientation of diazanaphthalenes in nematic solvents show that nitrogen atoms in the ring framework affect the direction of principal orientation, which does not follow either the maximum molecular dimension or the inertial axis.

scholarly journals The Molecular Structure of 2,5-Dihydrofuran from the Analysis of the Nematic Liquid Crystal Nuclear Magnetic Resonance Spectrum

1974 ◽  
Vol 52 (2) ◽  
pp. 281-286 ◽  
Author(s):  
K. C. Cole ◽  
D. F. R. Gilson
Keyword(s):  
Molecular Structure ◽  
Nuclear Magnetic Resonance ◽  
Liquid Crystal ◽  
Magnetic Resonance ◽  
Nuclear Magnetic Resonance Spectrum ◽  
Nematic Liquid Crystal ◽  
Nematic Phase ◽  
Resonance Spectrum ◽  
Coupling Constants ◽  
Ring Puckering

The nematic phase n.m.r. spectrum of partially oriented 2,5-dihydrofuran has been analyzed. Corrections to the structure for ring puckering and methylene rocking motions, according to the model due to Malloy, give improved agreement between experimental and calculated direct dipole–dipole coupling constants.

Studies of specifically fluorinated carbohydrates. Part I. Nuclear magnetic resonance studies of hexopyranosyl fluoride derivatives

1969 ◽  
Vol 47 (1) ◽  
pp. 1-17 ◽  
Author(s):  
L. D. Hall ◽  
J. F. Manville ◽  
N. S. Bhacca
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Angular Dependence ◽  
Chemical Shifts ◽  
Relative Orientation ◽  
Coupling Constants ◽  
Pyranose Ring ◽  
Spectral Parameters ◽  
Magnetic Resonance Studies ◽  
Nuclear Magnetic

A detailed study has been made of both the 1H and 19F nuclear magnetic resonance (n.m.r.) spectra of a series of hexopyranosyl fluoride derivatives. Some of the 1H spectra were measured at 220 MHz. The 1H spectral parameters define both the configuration and the conformation of each of these derivatives. Study of the 19F n.m.r. parameters revealed several stereospecific dependencies. The 19F chemical shifts depend upon, (a) the orientation of the fluorine substituent with respect to the pyranose ring and, (b) the relative orientation of other substituents attached to the ring; for acetoxy substituents, these configurational dependencies appear to be additive. The vicinal19F–1H coupling constants exhibit a marked angular dependence for which Jtrans = ca. 24 Hz whilst Jgauche = 1.0 to 1.5 Hz for [Formula: see text] and 7.5 to 12.6 Hz for [Formula: see text] The geminal19F–1H couplings depend on the orientation of the substituent at C-2; when this substituent is equatorial JF,H is ca. 53.5 Hz and when it is axial the value is ca. 49 Hz.

Studies of specifically fluorinated carbohydrates. Part II. Nuclear magnetic resonance studies of pentopyranosyl fluoride derivatives

1969 ◽  
Vol 47 (1) ◽  
pp. 19-30 ◽  
Author(s):  
L. D. Hall ◽  
J. F. Manville
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Nuclear Magnetic Resonance Spectroscopy ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Resonance Spectroscopy ◽  
Magnetic Resonance Studies ◽  
Conformational Model ◽  
Nuclear Magnetic

Detailed studies, by 1H and 19F nuclear magnetic resonance spectroscopy, of a series of fully esterified pentopyranosyl fluorides, show that all such derivatives favor that conformer in which the fluorine substituent is axially oriented. This conclusion is supported by separate considerations of the vicinal and geminal19F–1H and 1H–1H coupling constants, of the long-range (4J) 1H–1H and 19F–1H coupling constants and of the 19F chemical shifts. The limitations of the above conformational model are discussed.

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