Powder Crystallography by Combined Crystal Structure Prediction and High-Resolution ¹H Solid-State NMR Spectroscopy

Abstract

A fast method for crystal structure determination using crystal structure prediction and solid-state (1)H NMR is presented. This technique does not need any prior knowledge except the chemical formula; resonance assignment is not necessary. Starting from an ensemble of predicted crystal structures for powdered thymol, comparison between experimental and calculated (1)H solid-state isotropic NMR chemical shifts is sufficient to determine which predicted structure corresponds to the powder under study. The same approach using proton-proton spin-diffusion data is successful and can be used for cross-validation.

Probing Intermolecular Crystal Packing in γ-Indomethacin by High-Resolution 1H Solid-State NMR Spectroscopy

“…19 It is to be envisaged that such NMR crystallography approaches will find increasing application in the context of probing and understanding the solid-state structures adopted by organic molecules. Notably, such an understanding of intermolecular interactions is very valuable for rationalising the observed physical properties and behaviour of advanced pharmaceutical solids, e.g., co-crystals.…”

“…[10][11][12]14,15 The emerging field of NMR crystallography of organic solids employs experimental solid-state NMR usually in combination with calculation to probe solid-state structures. [16][17][18][19][20] In the context of organic molecules, a particular focus is upon the interactions that govern the adopted intermolecular packing, notably hydrogen bonding and aromatic - effects. 1 H solid-state NMR is well suited to this challenge on account of the marked sensitivity of the 1 H chemical shift to hydrogen bonding and aromatic ring current effects.…”

Magnesium incorporation into hydroxyapatite

“…The PBE generalised gradient approximation was used and the valence electrons were described by norm conserving pseudopotentials [72] 43 Ca and 25 Mg, the quadrupolar parameters C Q and η were also analysed. [38] It should be noted that based on previous studies and our own experience, the error on calculated 1 H and 31 P isotropic chemical shifts is estimated at ~0.4 [77] and 0.7 ppm, [78] respectively, whereas it is ~3 to 5 ppm on 43 Ca and 25 Mg isotropic chemical shifts, and ~0.5 to 2 MHz on 43 Ca and 25 Mg C Q values, [37,39] respectively. The four Ca(I) ions in the unit cell are usually referred to as "columnar calcium sites", because they form single atomic columns perpendicular to the basal plane.…”

Zero Thermal Expansion in ZrMgMo3O12: NMR Crystallography Reveals Origins of Thermoelastic Properties

“…This approach has come to be known as NMR crystallography. 36,37 Spin diffusion data have been used to determine the crystal packing of organic molecules, 38−40 and 1 H chemical shifts have been used either explicitly 41 or as a crystal structure selection parameter 42,43 when performing computational crystal structure predictions. Information concerning the connectivity in zeolites 44,45 and aluminophosphates 46−48 has also been used to solve the crystal structure of framework systems ab initio.…”