High-resolution solid-state NMR exp

High-resolution solid-state NMR experiments were conducted at room temperature either using a Bruker AV500 spectroscopy (125 MHz for 13 C and 500 MHz for 1 H) or a Varian NMR300 System (75 MHz for 13C and 300 MHz for 1H). 13C NMR spectra were observed under cross polarization (CP), magic angle spinning (MAS) and high power dipolar decoupling (DD) conditions.

The 90◦ pulse for 1 H and 13 C channels was 2.9 or 5.5