Accession Number:

AD0702359

Title:

THE PROTON RELAXATION AND OVERHAUSER EFFECT IN THE NUCLEAR MAGNETIC RESONANCE SPECTRA OF SOME AMIDES,

Descriptive Note:

Corporate Author:

NATIONAL RESEARCH COUNCIL OF CANADA OTTAWA (ONTARIO) DIV OF APPLIED CHEMISTRY

Personal Author(s):

Report Date:

1969-06-19

Pagination or Media Count:

15.0

Abstract:

The relaxation behavior of some amides was investigated in their high resolution spectra by the direct saturation-recovery and Overhauser effect methods. The recovery curves and steady-state Overhauser effects were obtained for solutions of dimethylformamide with double- and triple-resonance irradiations. The results were analyzed for 3- and 4-spin systems and the values of relaxation parameters were calculated. It was shown that for dimethylformamide the one-exponential recovery curve approximation gives the T1 values with a precision better than experimental error plus or minus 2. The observed difference in relaxation times for methyl group protons was explained by different correlation times and more restricted rotation of 1 of the groups. The correlation times for dipole-dipole interactions of methyl groups with the formyl proton were also evaluated with some reasonable assumptions. The change of the relaxation rate of N-methyl protons in C6H6 and C6D6 solutions was explained by formation of the collision complex with amide molecules and specific intermolecular dipole-dipole proton interaction. This effect could be useful for determination of the cis- and trans-conformations in N-methyl substituted amides and peptides as an absolute method because it does not require measurements on both isomers. Author

Subject Categories:

  • Atomic and Molecular Physics and Spectroscopy

Distribution Statement:

APPROVED FOR PUBLIC RELEASE