“Efficient measurement of the sign and the magnitude of long-range proton-carbon coupling constants from a spin-state-selective HSQMBC-COSY experiment”, by Josep Saurí and Teodor Parella; Magn. Reson. Chem. 2012, 50, 717-721. DOI:10.1002/mrc.3867
A spin-state-selective HSQMBC-COSY experiment is proposed to measure the sign and the magnitude of long-range proton-carbon coupling constants (nJ(CH); n>1) either for protonated and for non-protonated carbons in small molecules. The simple substitution of the selective 180º 1H 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 facilitates a final COSY transfer between coupled protons. The successful implementation of the IPAP principle lead to separate mixed-phase α/β cross-peaks from which nJ(CH) can be easily measured by analysing their relative frequency displacements in the detected dimension.
Pulse Program Code for Bruker: selHSQMBC-COSY