Precise Measurement of Long-Range Heteronuclear Coupling Constants by a Novel Broadband Proton-Proton-Decoupled CPMG-HSQMBC Method

A broadband proton-proton-decoupled CPMG-HSQMBC method for the precise and direct measurement of long-range heteronuclear coupling constants is presented. The Zangger-Sterk-based homodecoupling scheme reported herein efficiently removes unwanted proton-proton splittings from the heteronuclear multiplets, so that the desired heteronuclear couplings can be determined simply by measuring frequency differences between singlet maxima in the resulting spectra. The proposed pseudo-1D/2D pulse sequences were tested on nucleotides, a metal complex incorporating P heterocycles, and diglycosyl (di)selenides, as well as on other carbohydrate derivatives, for the extraction of (n)J(H-1, P-31), (n)J(H-1, Se-77), and (n)J(H-1, C-13) values, respectively.