High-Resolution ¹⁴ N Solid-State NMR Spectroscopy.

Area of Science:

• Solid-state NMR Spectroscopy
• Materials Science
• Inorganic Chemistry

Background:

• Nuclear Magnetic Resonance (NMR) spectroscopy is a powerful tool for determining molecular structure and dynamics.
• Solid-state NMR presents unique challenges compared to solution-state NMR, particularly for quadrupolar nuclei like nitrogen-14.
• Isotope enrichment is often required to obtain high-quality NMR spectra, which can be expensive and time-consuming.

Purpose of the Study:

• To demonstrate the feasibility of obtaining nitrogen NMR parameters in the solid state without the need for expensive isotope enrichment.
• To determine the isotropic chemical shifts for hexagonal boron nitride (h-BN) and cubic boron nitride (c-BN).
• To measure the quadrupole coupling for hexagonal boron nitride (h-BN).

Main Methods:

• Utilized magic angle spinning (MAS) NMR spectroscopy at 28.809 MHz.
• Acquired 14N MAS NMR spectra of hexagonal and cubic boron nitride samples.
• Analyzed spectral data to extract isotropic chemical shifts and quadrupole coupling parameters.

Main Results:

• Successfully obtained solid-state nitrogen NMR parameters for both hexagonal and cubic boron nitride.
• Reported, for the first time, the isotropic chemical shifts for h-BN and c-BN.
• Determined the quadrupole coupling for the hexagonal boron nitride modification.

Conclusions:

• Solid-state nitrogen NMR is achievable without costly isotope enrichment, broadening its applicability.
• The reported NMR parameters provide valuable insights into the electronic structure and bonding in boron nitride materials.
• This methodology enables the characterization of nitrogen-containing solids where isotope enrichment is not practical.