Zero-field NMR and millitesla-SLIC spectra for > 200 molecules from density functional theory and spin dynamics

NMR is usually performed at magnetic fields of 1 T and above to obtain sufficient sensitivity and spectral dispersion to identify chemicals based on chemical shifts and J couplings. At lower fields, the advent of hyperpolarization technologies and sensitive low-field detectors can address sensitivity concerns. However, it remains disputed whether spectral signatures at low fields are sufficient for chemical identification. Here, we report an all–electron DFT batch production of J coupling NMR spectra at zero field and 6.5 mT for over 200 small molecules. We found that ultra-low-field NMR can be used for unique chemical identification. In the developed computational tool chain, we first used the all-electron FHI-aims code to calculate the molecular J couplings and chemical shifts. We then fed the calculated NMR parameters into the NMR simulation package SPINACH to simulate both heteronuclear J coupling spectra at zero-field, and spin-lock induced crossing (SLIC) spectra at 6.5 mT. The resulting spectra demonstrate that ultra-low-field NMR spectra can represent unique identifiers of chemical structure for small molecules.