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In this study, we benchmark density functional theory gauge-including projector-augmented-wave (GIPAW) chemical shieldings against molecular shieldings for which basis set completeness has been achieved [Jensen et al., Phys. Chem. Chem. Phys. 18, 21145 (2016)]. We demonstrate the importance of two-center corrections for GIPAW hydrogen shieldings. For the other nuclei studied, standard GIPAW is sufficiently accurate. We find that GIPAW can be pushed to closely approach the basis set limit. The only source of small inaccuracies lies in the contribution to the shielding that is caused by surface currents, which we estimate comparing GIPAW susceptibilities to converged molecular magnetizabilities.
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http://dx.doi.org/10.1063/5.0069637 | DOI Listing |
J Chem Phys
March 2025
Crystallography and Geomaterials, Faculty of Geosciences, University of Bremen, Klagenfurter Straße 2-4, 28359 Bremen, Germany.
The quadrupole coupling constant CQ and the asymmetry parameter η of the aluminum nuclei in two polymorphs of the complex aluminum hydride CsAlH4 are determined from both 27Al magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectra and 27Al NMR spectra recorded for stationary samples by using the Solomon echo sequence. The accuracy with which these parameters can be determined from the static spectra [CsAlH4(o): CQ = (1.42 ± 0.
View Article and Find Full Text PDFMagn Reson Chem
January 2025
NMR Research Centre, Bangalore, India.
Glutathione (GSH) and its oxidized dimer (GSSG) play an important role in living systems as an antioxidant, balancing the presence of reactive oxygen species (ROS). The central thiol (-S-S-) bond in GSSG can undergo free rotation, providing multiple conformations with respect to the S-S bridge. The six titratable sites of GSSG, which are influenced by pH variations, affect these conformations in solution, whereas in solids, additionally crystal packing effects come into play.
View Article and Find Full Text PDFJ Phys Chem A
March 2024
Department of Physics, University of Warwick, Coventry CV4 7AL, U.K.
The Δδ regression approach of Blade et al. [ 2020, 124(43), 8959-8977] for accurately discriminating between solid forms using a combination of experimental solution- and solid-state NMR data with density functional theory (DFT) calculation is here extended to molecules with multiple conformational degrees of freedom, using furosemide polymorphs as an exemplar. As before, the differences in measured H and C chemical shifts between solution-state NMR and solid-state magic-angle spinning (MAS) NMR (Δδ) are compared to those determined by gauge-including projector augmented wave (GIPAW) calculations (Δδ) by regression analysis and a -test, allowing the correct furosemide polymorph to be precisely identified.
View Article and Find Full Text PDFChemistryOpen
January 2024
Crystallography & Geomaterials Research, Faculty of Geosciences, University of Bremen, Klagenfurter Straße 2-4, 28359, Bremen, Germany.
The quadrupole coupling constant C and the asymmetry parameter η have been determined for two complex aluminium hydrides from Al NMR spectra recorded for stationary samples by using the Solomon echo sequence. The thus obtained data for KAlH (C =(1.30±0.
View Article and Find Full Text PDFJ Pharm Sci
July 2023
Department of Physics, University of Warwick, Coventry, CV4 7AL, UK. Electronic address:
Lorlatinib is an active pharmaceutical ingredient (API) used in the treatment of lung cancer. Here, an NMR crystallography analysis is presented whereby the single-crystal X-ray diffraction structure (CSD: 2205098) determination is complemented by multinuclear (H, C, /N, F) magic-angle spinning (MAS) solid-state NMR and gauge-including projector augmented wave (GIPAW) calculation of NMR chemical shifts. Lorlatinib crystallises in the P2 space group, with two distinct molecules in the asymmetric unit cell, Z' = 2.
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