Heteronuclear Correlation Solid-state NMR Spectroscopy with Indirect Detection under Fast Magic-angle Spinning Check Access

The development of probes capable of magic-angle spinning (MAS) at very high rates, which now exceed 100 kHz, has revolutionized solid-state NMR spectroscopy. The introductory parts of this chapter describe the basic aspects of fast MAS and illuminate the main advantages of this remarkable technology. Thereafter, practical advice is given on the use and maintenance of fast MAS instrumentation. The bulk of the text, however, describes the principles and hands-on aspects of heteronuclear correlation (HETCOR) experiments performed under fast MAS with indirect detection of lower-γ nuclei. We specifically focus on experimental strategies used in our laboratories to optimize the pulse sequences akin to the HSQC and HMQC experiments known in solution NMR. The HSQC scheme can be used to measure the spectra of dilute lower-γ spin-1/2 nuclei, while the HMQC sequence is best suited to measure spectra that are broadened by the quadrupolar interaction or large chemical shift anisotropy. Numerous through-space and through-bond ¹H{¹³C}, ¹H{¹⁵N} and ¹H{¹⁴N} HETCOR spectra are presented to demonstrate the resolution and sensitivity benefits of indirect detection and illustrate the optimization strategies. We hope that these examples will showcase the merits of indirect detection and encourage the readers to make the most of these experiments.