title: Efficient measurement of the sign and the magnitude of long-range proton-carbon coupling constants from a spin-state-selective HSQMBC-COSY experiment.
abstract: 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.
authors.affiliation: Servei de Ressonància Magnètica Nuclear, Universitat Autònoma de Barcelona, E-08193-Bellaterra, Barcelona, Spain.
authors.forename: Josep
authors.initials: J
authors.lastname: Saurí
authors.forename: Teodor
authors.initials: T
authors.lastname: Parella
mesh_terms: D002244:Carbon / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D011522:Protons; D012015:Reference Standards; D013331:Strychnine / Q000737:chemistry*
chemical_list: D011522:Protons; D002244:Carbon; D013331:Strychnine