Comment on “On the Difficulties and Pitfalls with the Analysis of Solid‑State 13C NMR Spectra in Graphitic Materials”

Abstract

A recent paper on solid-state 13C nuclear magnetic resonance in graphitic materials reports on the difficulties with the interpretation of the spectra and presents alternative methods to obtain informative experimental data. Therein, special emphasis is placed on the role of dipole–dipole interactions in the case of 13C-enriched samples and on the assignment of the 13C spectral components beyond the common “graphitic range”. Here, we show that the consideration of the experimental conditions, namely, the speed of magic angle spinning, plays a more important role in the data interpretation. Further, we provide the experimental and theoretical evidences that the appearance of the 13C resonances shifted upfield from the typical sp2-hybridized carbon range is not surprising, but rather exhibits a characteristic feature of the graphitic materials with specific morphology. Finally, we show that analysis of the anisotropy of the chemical shift tensor is informative even in the case of very broad 13C spectra and supports the microscopy observations.