title: Anomalous nuclear Overhauser effects in carbon-substituted aziridines: scalar cross-relaxation of the first kind.
abstract: Anomalous NOESY cross-peaks that cannot be explained by dipolar cross-relaxation or chemical exchange are described for carbon-substituted aziridines. The origin of these is identified as scalar cross-relaxation of the first kind, as demonstrated by a complete theoretical description of this relaxation process and by computational simulation of the NOESY spectra. It is shown that this process relies on the stochastic modulation of J-coupling by conformational transitions, which in the case of aziridines arise from inversion at the nitrogen center. The observation of scalar cross-relaxation between protons does not appear to have been previously reported for NOESY spectra. Conventional analysis would have assigned the cross-peaks as being indicative of a chemical exchange process occurring between correlated spins, were it not for the fact that the pairs of nuclei displaying them cannot undergo such exchange.
authors: School of Chemistry, University of Southampton, Highfield Campus, Southampton SO17 1BJ (UK).
authors: Ilya
authors: I
authors: Kuprov
authors: David M
authors: DM
authors: Hodgson
authors: Johannes
authors: J
authors: Kloesges
authors: Christopher I
authors: CI
authors: Pearson
authors: Barbara
authors: B
authors: Odell
authors: Timothy D W
authors: TD
authors: Claridge
mesh_terms: D001388:Aziridines / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D009587:Nitrogen Isotopes / Q000737:chemistry; D011522:Protons
chemical_list: D001388:Aziridines; D009587:Nitrogen Isotopes; D011522:Protons; D002244:Carbon
keywords: NMR spectroscopy; NMR theory; Overhauser effect; aziridines; scalar relaxation
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