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Measurement of long‐range heteronuclear coupling constants using the peak intensity in classical 1D HMBC spectra
Author(s) -
Bigler Peter,
Furrer Julien
Publication year - 2018
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.4713
Subject(s) - heteronuclear molecule , homonuclear molecule , chemistry , coupling constant , multiplet , spectral line , pulse sequence , intensity (physics) , nuclear magnetic resonance , range (aeronautics) , analytical chemistry (journal) , pulse (music) , molecular physics , atomic physics , stereochemistry , nuclear magnetic resonance spectroscopy , physics , molecule , quantum mechanics , organic chemistry , materials science , voltage , composite material
In this contribution, we show that the magnitude of heteronuclear long‐range coupling constants can be directly extracted from the classical 1D HMBC spectra, as all multiplet lines of a cross‐peak always and exclusively vanish for the condition Δ = k / n J CH . To the best of our knowledge, this feature of the classical HMBC has not yet been noticed and exploited. This condition holds true, irrespective of the magnitude and numbers of additional active and passive homonuclear n J HH′ couplings. Alternatively, the n J CH value may also be evaluated by fitting the peak's intensity in the individual spectra to its simple sin( π n J CH Δ)exp(−Δ/ T 2eff ) dependence. Compared to the previously proposed J ‐HMBC sequences that also use the variation of the cross‐peak's intensity for extracting the coupling constants, the classical HMBC pulse sequence is significantly more sensitive.