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Efficient measurement of the sign and the magnitude of long‐range proton‐carbon coupling constants from a spin‐state‐selective HSQMBC‐COSY experiment
Author(s) -
Saurí Josep,
Parella Teodor
Publication year - 2012
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.3867
Subject(s) - heteronuclear molecule , chemistry , protonation , proton , coupling constant , sign (mathematics) , range (aeronautics) , spin (aerodynamics) , coupling (piping) , carbon 13 , proton spin crisis , molecule , molecular physics , atomic physics , analytical chemistry (journal) , physics , nuclear physics , thermodynamics , quantum mechanics , ion , organic chemistry , mathematical analysis , materials science , mechanical engineering , mathematics , engineering , composite material
A spin state‐selective Heteronuclear Single‐Quantum Multiple‐Bond Connectivities (HSQMBC‐COSY) experiment is proposed to measure the sign and the magnitude of long‐range proton‐carbon coupling constants ( n J (CH); n > 1) either for protonated or for non‐protonated carbons in small molecules. The simple substitution of the selective 180° 1 H pulse in the original selHSQMBC pulse scheme by a hard one allows the simultaneous evolution of both proton‐proton and proton‐carbon coupling constants during the refocusing period and enables a final COSY transfer between coupled protons. The successful implementation of the IPAP principle leads to separate mixed‐phase α/β cross‐peaks from which n J (CH) values can be easily measured by analyzing their relative frequency displacements in the detected dimension. Copyright © 2012 John Wiley & Sons, Ltd.