The enrichment ratio of atomic contacts in crystals, an indicator derived from the Hirshfeld surface analysis
An enrichment ratio is derived from the decomposition of the crystal contact surface between pairs of interacting chemical species. The propensity of different contact types to form is investigated.
(2S,3S)-2-(N,N-dibenzylamino)butane-1,3-diol refined using a multipolar atom model.
The crystal structure of the title compound, C18H23NO2, was determined using the experimental library multipolar atom model. The refinement showed a significant improvement of crystallographic statistical indices when compared with a conventional spherical neutral atom refinement.
A polar/π model of interactions explains face-to-face stacked quinoid rings: a case study of the crystal of potassium hydrogen chloranilate dihydrate
International audience; The nature of interactions between face-to-face staggered stacked quinoid rings with pi-systems, observed with a short inter-ring centroid. centroid distance, is analyzed by experimental and theoretical methods. Charge density studies based on X-ray diffraction and DFT calculations, complemented by impedance spectroscopy, were employed to define the electronic and structural characteristics of the quinoid rings responsible for their interactions within the crystal packing. The crystal packing is mainly stabilized by strong electrostatic interactions between the K+ cation and the hydrogen chloranilate anion. The proximity and orientation of the stacked quinoid rings i…
4-Benzoyl-3,4-dihydro-2 H -1,4-benzoxazine-2-carbonitrile: refinement using a multipolar atom model
The structural model for the title compound, C(16)H(12)N(2)O(2), was refined using a multipolar atom model transferred from an experimental electron-density database. The refinement showed some improvements of crystallographic statistical indices when compared with a conventional spherical neutral-atom refinement. The title compound adopts a half-chair conformation. The amide N atom lies almost in the plane defined by the three neighbouring C atoms. In the crystal structure, molecules are linked by weak intermolecular C-H...O and C-H...pi hydrogen bonds.
5-(3,4-Dimethoxybenzyl)-7-isopropyl-1,3,5-triazepane-2,6-dione acetonitrile solvate refined using a multipolar atom model
International audience; The crystal structure of the title compound, C16H23N3O4·CH3CN, was refined using a multipolar atom model transferred from an experimental electron-density database. The refinement showed some improvement in crystallographic statistical indices compared with the independent atom model. The triazepane ring adopts a twist-boat conformation. In the crystal structure, the molecule forms intermolecular contacts with 14 different neighbours. There are two N-H...O and one C-H...O intermolecular hydrogen bond.
On the application of an experimental multipolar pseudo-atom library for accurate refinement of small-molecule and protein crystal structures
International audience; With an increasing number of biomacromolecular crystal structures being measured to ultra-high resolution, it has become possible to extend to large systems experimental charge-density methods that are usually applied to small molecules. A library has been built of average multipole populations describing the electron density of chemical groups in all 20 amino acids found in proteins. The library uses the Hansen & Coppens multipolar pseudo-atom model to derive molecular electron density and electrostatic potential distributions. The library values are obtained from several small peptide or amino acid crystal structures refined against ultra-high-resolution X-ray diff…
Charge-density analysis of 1-nitroindoline: refinement quality using free R factors and restraints
Nitramines and related N-nitro compounds have attracted significant attention owing to their use in rocket fuel and as explosives. The charge density of 1-nitroindoline was determined experimentally and from theoretical calculations. Electron-density refinements were performed using the multipolar atom formalism. In order to design the ideal restraint strategy for the charge-density parameters, R-free analyses were performed involving a series of comprehensive refinements. Different weights were applied to the charge-density restraints, namely the similarity between chemically equivalent atoms and local symmetry. Additionally, isotropic thermal motion and an anisotropic model calculated by …
Charge-density analysis of 1-nitroindoline: refinement quality using free R factors and restraints. Corrigendum
The D e (dissociation energy) values in Table 6 of the article by Zarychta et al. [(2011). Acta Cryst. B67, 250–262] are corrected.
Cholesterol oxidase: ultrahigh-resolution crystal structure and multipolar atom model-based analysis
International audience; Author(s) of this paper may load this reprint on their own web site or institutional repository provided that this cover page is retained. Republication of this article or its storage in electronic databases other than as specified above is not permitted without prior permission in writing from the IUCr. For further information see http://journals.iucr.org/services/authorrights.html Acta Cryst. (2015). D71, 954-968 Zarychta et al. · Cholesterol oxidase research papers 954 http://dx. Examination of protein structure at the subatomic level is required to improve the understanding of enzymatic function. For this purpose, X-ray diffraction data have been collected at 100…
CCDC 1403137: Experimental Crystal Structure Determination
Related Article: Krešimir Molčanov, Jernej Stare, Biserka Kojić-Prodić, Claude Lecomte, Slimane Dahaoui, Christian Jelsch, Emmanuel Wenger, Ana Šantić, Bartosz Zarychta|2015|CrystEngComm|17|8645|doi:10.1039/C5CE01037C