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Measurement of the sign and the magnitude of heteronuclear coupling constants from spin‐state‐edited J ‐cross‐polarization NMR experiments
Author(s) -
Parella Teodor,
Belloc Jordi,
SánchezFerrando Francesc
Publication year - 2004
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1416
Subject(s) - heteronuclear molecule , homonuclear molecule , chemistry , coupling constant , protonation , polarization (electrochemistry) , coherence (philosophical gambling strategy) , analytical chemistry (journal) , molecular physics , nuclear magnetic resonance , molecule , nuclear magnetic resonance spectroscopy , stereochemistry , physics , organic chemistry , quantum mechanics , ion
New spin‐state‐selective (S 3 ) NMR pulse sequences exclusively applying cross‐polarization schemes to achieve optimum homonuclear and heteronuclear 1 HX coherence transfer are reported for the simple and accurate measurement of the magnitude and sign of heteronuclear coupling constants for samples at natural abundance. The proposed spin‐edited HCP‐TOCSY experiments are based on clean heteronuclear S 3 excitation, generated by simultaneous co‐addition of two independent in‐phase and anti‐phase components created during the mixing heteronuclear J ‐cross‐polarization (HCP) step, which is finally transferred to other protons by a conventional homonuclear TOCSY mechanism. Selective 1D and non‐selective 2D approaches for the easy determination of long‐range proton–carbon and proton–nitrogen coupling constants on any protonated and non‐protonated heteronuclei are presented and discussed for several organic molecules. Copyright © 2004 John Wiley & Sons, Ltd.