ISSN:
0749-1581
Keywords:
1H NMR
;
2D EXSY NMR
;
mixing time
;
complete lineshape analysis
;
double-fit method
;
barriers to restricted rotation
;
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
A procedure for the estimation of the mixing time between the last two 90° pulses in the classic three-pulse sequence NOESY/EXSY is proposed and tested and some considerations for the treatment of the two-dimensional (2D) 1H NMR exchange spectra are given. The rate constants are thus obtained with reasonable precision. This procedure was followed to obtain the 2D spectra of the model compound α-[bis(dimethylamino)methylene]-4-nitrophenylacetonitrile, which represents a four-site exchange system. The barriers to restricted rotations found in this compound were also determined from one-dimensional (1D) 1H NMR spectra, which were processed with the iterative complete lineshape analysis (CLSA) method. The double-fit approach was incorporated in the CLSA method. It is shown that the results from the 2D dynamic NMR spectral studies corroborate those obtained by the CLSA double-fit method.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/mrc.1260330909
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