scholarly journals Resolving alternative organic crystal structures using density functional theory and NMR chemical shifts

2020 ◽  
Vol 11 (11) ◽  
pp. 2987-2992 ◽  
Author(s):  
Cory M. Widdifield ◽  
James D. Farrell ◽  
Jason C. Cole ◽  
Judith A. K. Howard ◽  
Paul Hodgkinson
Keyword(s):  
Crystal Structure ◽  
Density Functional Theory ◽  
Crystal Structures ◽  
Density Functional ◽  
Chemical Shifts ◽  
Organic Crystal ◽  
Functional Theory ◽  
Nmr Chemical Shifts ◽  
Structure Determinations

DFT optimisation often resolves conflicting crystal structure determinations, with NMR shifts helping in cases where optimisation diverges to different structures.

scholarly journals Validation of experimental molecular crystal structures with dispersion-corrected density functional theory calculations

2010 ◽  
Vol 66 (5) ◽  
pp. 544-558 ◽  
Author(s):  
Jacco van de Streek ◽  
Marcus A. Neumann
Keyword(s):  
Density Functional Theory ◽  
Crystal Structures ◽  
Density Functional ◽  
Unit Cell ◽  
Organic Crystal ◽  
Large Temperature ◽  
Unit Cell Parameters ◽  
Functional Theory ◽  
Cell Parameters ◽  
Experimental Crystal

This paper describes the validation of a dispersion-corrected density functional theory (d-DFT) method for the purpose of assessing the correctness of experimental organic crystal structures and enhancing the information content of purely experimental data. 241 experimental organic crystal structures from the August 2008 issue of Acta Cryst. Section E were energy-minimized in full, including unit-cell parameters. The differences between the experimental and the minimized crystal structures were subjected to statistical analysis. The r.m.s. Cartesian displacement excluding H atoms upon energy minimization with flexible unit-cell parameters is selected as a pertinent indicator of the correctness of a crystal structure. All 241 experimental crystal structures are reproduced very well: the average r.m.s. Cartesian displacement for the 241 crystal structures, including 16 disordered structures, is only 0.095 Å (0.084 Å for the 225 ordered structures). R.m.s. Cartesian displacements above 0.25 Å either indicate incorrect experimental crystal structures or reveal interesting structural features such as exceptionally large temperature effects, incorrectly modelled disorder or symmetry breaking H atoms. After validation, the method is applied to nine examples that are known to be ambiguous or subtly incorrect.

scholarly journals Correction: Fragment density functional theory calculation of NMR chemical shifts for proteins with implicit solvation

2015 ◽  
Vol 17 (18) ◽  
pp. 12367-12367
Author(s):  
Tong Zhu ◽  
Xiao He ◽  
John Z. H. Zhang
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Chemical Shifts ◽  
Density Functional Theory Calculation ◽  
Chem Phys ◽  
Implicit Solvation ◽  
Functional Theory ◽  
Nmr Chemical Shifts ◽  
Theory Calculation ◽  
Phys Chem Chem Phys

Correction for ‘Fragment density functional theory calculation of NMR chemical shifts for proteins with implicit solvation’ by Tong Zhu et al., Phys. Chem. Chem. Phys., 2012, 14, 7837–7845.

scholarly journals Oxoperoxo Vanadium(V) Complexes ofl-Lactic Acid: Density Functional Theory Study of Structure and NMR Chemical Shifts

2008 ◽  
Vol 47 (16) ◽  
pp. 7317-7326 ◽  
Author(s):  
Licínia L. G. Justino ◽  
M. Luísa Ramos ◽  
Fernando Nogueira ◽  
Abilio J. F. N. Sobral ◽  
Carlos F. G. C. Geraldes ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Lactic Acid ◽  
Density Functional ◽  
Chemical Shifts ◽  
Density Functional Theory Study ◽  
Functional Theory ◽  
Nmr Chemical Shifts

scholarly journals Substituent Effects in 3,3’ Bipyrazole Derivatives. X-ray Crystal Structures, Molecular Properties and DFT Analysis

2021 ◽  
Vol 68 (3) ◽  
pp. 718-727
Author(s):  
Ibrahim Bouabdallah ◽  
Tarik Harit ◽  
Mahmoud Rahal ◽  
Fouad Malek ◽  
Monique Tillard ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Density Functional Theory ◽  
Solid State ◽  
Dft Calculations ◽  
Single Crystal ◽  
Crystal Structures ◽  
Density Functional ◽  
Substituent Effects ◽  
Functional Theory ◽  
X Ray

The single crystal X-ray structure of new 1,1’-bis(2-nitrophenyl)-5,5’-diisopropyl-3,3’-bipyrazole, 1, is triclinic P I–, a = 7.7113(8), b = 12.3926(14), c = 12.9886(12) Å, α = 92.008(8), β = 102.251(8), γ = 99.655(9)°. The structural arrangement is compared to that of 5,5’-diisopropyl-3,3’-bipyrazole, 5, whose single crystal structure is found tetragonal I41/a, a = b = 11.684(1), c = 19.158(1) Å. The comparison is also extended to the structures previously determined for 1,1’-bis(2-nitrophenyl)-5,5’-propyl-3,3’-bipyrazole, 2, 1,1’-bis(4-nitrophenyl)-5,5’-diisopropyl-3,3’-bipyrazole, 3, and 1,1’-bis(benzyl)-5,5’-diisopropyl-3,3’-bipyrazole, 4. Density Functional Theory (DFT) calculations are used to investigate the molecular geometries and to determine the global reactivity parameters. The geometry of isolated molecules and the molecular arrangements in the solid state are analyzed according to the nature of the groups connected to the bipyrazole core.

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