Frequency-selective Heteronuclear Correlation (FS-HETCOR) Experiments in Solid-State NMR

Heteronuclear correlation (HETCOR) is critical to obtain structural information in solid-state nuclear magnetic resonance (NMR). We propose novel frequency-selective Heteronuclear correlation (FS-HETCOR) experiments to selectively enhance the inter-atomic correlations of interest. FS-HETCOR relies on heteronuclear selective phase-optimized recoupling (SPRx), which is frequency-selective in heteronuclear recouping without using selective pulses. Compared to regular HETCOR, FS-HETCOR selectively enhances the desired heteronuclear correlations by a factor of up to 5 and suppresses the unwanted ones to 10% as demonstrated in 1H-19F and 1H-13C experiments under fast magic-angle spinning (MAS). Moreover, FS-HETCOR can theoretically be applied at arbitrary MAS rates by utilizing various SPRx schemes. We believe that the method will enhance the ability of solid-state NMR to probe heteronuclear structural information.