Measurement of long-range proton-carbon coupling constants from pure in-phase 1D multiplets

“Measurement of long-range proton-carbon constants from pure in-phase 1D multiplets”, by Juan F. Espinosa, Paloma Vidal, Teodor Parella and Sergi Gil: Magnetic Resonance in Chemistry 49, 502-507 (2011). DOI:10.1002/mrc.2782

A double-selective variant of the SELINCOR pulse sequence yields 1D proton multiplets that exhibit pure absortive in-phase lineshapes for precise measurement of specific long-range proton-carbon coupling constants in small organic molecules at natural abundance.

The double-selective SELINCOR pulse sequence is a carbon-selective 1D HSQC experiment developed for direct and accurate measurement of coupling constants between protons and non-protonated carbons, althought it can be used also for protonated carbons. The inter-pulse delays are optimized for small coupling constants while a 90º 13C pulse before acquisition removes antiphase distortions yielding a pure absortive in-phase signal split by the proton-proton and proton-carbon coupling constant. In this way, heteronuclear couplings can be measured by peak separation or using a simple peak-fitting procedure.

Expansions of (A,B) Conventional 1H-NMR spectra and (C,D) double-selective SELINCOR spectra showing proton-carbon multiplet with pure absortive in-phase lineshape for precise measurement of specific long-range proton-carbon coupling constants.

Bruker Pulse program: 1dghsqcdosel 

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