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