Accurate measurement of small heteronuclear coupling constants from pure-phase α/β HSQMBC cross-peaks

“Accurate measurement of small heteronuclear coupling constants from pure-phase α/β HSQMBC”, by Sergi Gil, Juan Félix Espinosa and Teodor Parella; Journal of Magnetic Resonance 213, 1, 145-150 (2011). DOI:10.1016/j.jmr.2011.09.036

A simple proton-selective α/β-HSQMBC experiment is proposed for the accurate measurement of long-range proton–carbon coupling constants (ⁿJ_CH) in small molecules without need for an individualized and time-consuming post-processing fitting procedure. The method acquires two pure-phase In-phase (IP) and Anti-phase (AP) multiplets completely free of any phase distortion due to the absence of J_HH evolution. Accurate ⁿJ_CH values can be directly measured analyzing the relative displacement of the resulting IPAP cross-peaks. Discussion about signal intensity dependence and cross-talk is made for a range of experimental conditions. The robustness of the method is evaluated by comparing the ⁿJ_CH value measured from the analysis of the three available IP, AP and IPAP multiplet patterns. Multiple-frequency and region-selective versions of the method can also be efficiently recorded provided that excited protons are not mutually coupled.

Combination of proton-selective IP and AP spectra provides two new pure-phase α and β subspectra facilitating the measurement of long-range coupling constants

Bruker pulse program: selhsqmbcipap2d

Related Post: A new way to measure small proton-carbon coupling constants. “IPAP-HSQMBC: Measurements of long-range heteronuclear coupling constants from spin-state selective multiplets”, by Sergi Gil, Juan Félix Espinosa and Teodor Parella; Journal of Magnetic Resonance, 207, 312-321 (2010).