A structure determination protocol based on combined analysis of 3D-ED data, powder XRD data, solid-state NMR data and DFT-D calculations reveals the structure of a new polymorph of L-tyrosine: data

The crystal structure of a new polymorph of L-tyrosine (denoted the β polymorph), prepared by crystallization from the gas phase following vacuum sublimation, was studied. Structure determination was carried out by combined analysis of three-dimensional electron diffraction (3D-ED) data and powder X-ray diffraction (XRD) data. Specifically, 3D-ED data were required for reliable unit cell determination and space group assignment, with structure solution carried out independently from both 3D-ED data and powder XRD data using the direct-space strategy for structure solution implemented using a genetic algorithm. Structure refinement was carried out both from powder XRD data using the Rietveld profile refinement technique and from 3D-ED data. The final refined structure was validated both by periodic DFT-D calculations, which confirm that the structure corresponds to an energy minimum on the energy landscape, and by the fact that the values of isotropic 13C NMR chemical shifts calculated for the crystal structure using DFT-D methodology are in good agreement with the experimental high-resolution solid-state 13C NMR spectrum.

Data presented are from 3D-ED, powder XRD and solid-state NMR. The 3D-ED data is a .hkl file consisting of values of h, k, l and integrated intensity. The PXRD data files consist of values of 2θ (°) and intensity. The NMR file consists of a header giving the spectral range and a list of intensities.

Research results based upon these data are pubilshed at DOI:10.1039/d1sc06467c