Themed collection NMR crystallography

This Faraday Discussion explored the field of NMR crystallography, considering recent developments in experimental and theoretical approaches, new advances in machine learning and applications to disordered, amorphous and dynamic materials.

We present an overview of current methods for chemical shift driven NMR crystallography, illustrated with applications to complex materials.

Octacalcium phosphate (OCP) exhibits water mobility, evidenced via variable-temperature NMR. Molecular-dynamics simulations then offer a new description of OCP symmetry.

A machine-learning approach for simulating Na/Al solid-state NMR spectra in zeolites was developed. Improved sampling provided insight into Al distributions and highlighted the importance of dynamical effects.

In this study, nuclear magnetic resonance (NMR) is used to investigate the crystallisation behaviour of aspirin within a mesoporous SBA-15 silica material.

Molecular dynamics (MD) simulations and chemical shifts from machine learning (ML) are used to rationalise key features of the ¹⁵N, ¹³C and ¹H NMR spectra of the amorphous form of the drug irbesartan.

The UC model assigns likelihoods to candidate structures in NMR crystallography based on a hierarchical Bayesian framework.

We report a quadrupolar guided NMR crystallography crystal structure prediction protocol as applied for pseudoephedrine HCl and ephedrine HCl. We explore the crystal structure prediction of pseudoephedrine HCl in the dosage form.

A new layered polymorph of Li₃NbO₄ with coplanar [Nb₄O₁₆]¹²⁻ clusters is discovered through ion exchange chemistry. The transformation of coplanar [Nb₄O₁₆]¹²⁻ into the supertetrahedral [Nb₄O₁₆]¹²⁻ clusters found in cubic c-Li₃NbO₄ is also explored.

The structure of an active pharmaceutical ingredient (API) is validated using solely ultra-fast ¹H-detected experiments and machine learning without the need for dynamic nuclear polarization.

We discuss the range of NMR techniques that have been utilized for in situ monitoring of crystallization processes, and new results are presented on several crystallization systems using the CLASSIC NMR strategy and other in situ NMR techniques.

We apply density functional theory (DFT) calculations to assign the experimental signals observed in ⁷Li NMR spectra of pristine and lithiated LiFeV₂O₇ framework.

mGGA exchange–correlation functionals give improved predictions over GGA functionals for NMR chemical shifts in a range of inorganic solids.

We determine the complete atomic-level structure of the amorphous form of the drug atuliflapon, a 5-lipooxygenase activating protein (FLAP) inhibitor, via chemical-shift-driven NMR crystallography.

Using multicomponent gels based on Phe and amino-L-phenylalanine (NH₂-Phe), we explore the trends of assembly and disassembly of the gels depending on their compositions and patterns of intermolecular interactions in the gel fibres and at the fibre/solution interfaces.

⁷ Li EFG reference scale: translation of first principles simulations to experimental quadrupolar couplings in solid state.

Using machine learning we are able simulate Li dynamics and predict the autocorrelation function for ⁷Li spin alignment echo NMR in crystalline and amorphous Li₃PS₄.

Machine-learning prediction of NMR tensors allows simulation NMR experiments at finite temperature for models of thousands of atoms.

We use a mesoscopic model to simulate NMR spectra of ions diffusing in carbon particles of various sizes. We obtain complex spectra, with broad and narrow peaks, and show that including polydispersity is essential to recover experimental features.

In this study, we have successfully developed a comprehensive high-throughput workflow for evaluating and predicting ¹⁷O NMR parameters in non-magnetic oxide crystals.

In this paper, we explore the importance of biasing structure refinement by model likelihood as a methodology for discriminating between different possible structure solutions.

This study has investigated the impact improving the quality of molecular crystal geometries can have on the accuracy of predicted ¹³C and ¹⁵N chemical shifts in organic crystals.