Nitroxide radical as a probe for molecular conformation. Part I. 13C NMR study of the interaction of N,N-dimethylamides with nitroxide radical
✍ Scribed by Iwona Wawer; Dieter Ströhl; Erich Kleinpeter
- Publisher
- John Wiley and Sons
- Year
- 1993
- Tongue
- English
- Weight
- 487 KB
- Volume
- 31
- Category
- Article
- ISSN
- 0749-1581
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✦ Synopsis
Abstract
^13^C NMR contact shifts induced by the 2,2,6,6,‐tetramethylpiperidine nitroxide radical (TMPN) were measured for N,N‐dimethyl‐para‐substituted benzamides and N,N‐dimethyl‐β‐bromo‐ and ‐α,β‐methylacrylamides. The shifts were linear functions of radical concentration, c~r~. It was found that N‐methyl group anti to the carbonyl group is a better acceptor site than the syn‐N‐methyl group and that there is a relationship between Δδ/dc~r~ and the non‐planarity of molecules of amides with an s‐skew conformation. The electrostatic potential of amide molecules obtained from MNDO calculations was used to predict the stereospecific interaction with radicals.