IFSERF, an isotope-filtered SERF experiment for the precise measurement of proton-proton coupling constants between chemically equivalent protons.

An isotope-filtered selective refocusing (IFSERF) experiment is presented for the sensitive and precise measurement of the proton-proton coupling constant between chemically equivalent protons. The 2D NMR method combines an initial doubly selective isotope filter based on heteronuclear cross-polarization followed by a selective J-resolved block. The coupling topologies obtained from several 2D variants of the IFSERF experiment are described for the simultaneous measurement of both proton-proton and proton-carbon coupling constants in the involved AA'XX' spin system. Application on the determination of the relative configuration of double bonds in symmetrical molecules is illustrated.