A method for visualization of the variation of noncovalent interactions in crystal structures of conformational polymorphs

Abstract

A method for clear visualization of the variation of noncovalent interactions in crystal structures of conformational polymorphs is developed and introduced. The first stage of the method establishes the characteristics of all, without exception, noncovalent interactions in all crystal structures under discussion. This is possible using a strict and objective method of construction of Voronoi-Dirichlet polyhedra within the framework of the stereoatomic model of crystal structures. The second stage of the method then involves plotting of diagrams, showing the relation between parameters characterizing interatomic interactions and chosen geometric parameters of molecules. Application of the title method to highly polymorphic systems of ROY and flufenamic acid allows several imperceptible features of real crystal structures to be revealed and determines the value of different types of interactions in their conformational polymorphs. The method is universal as it can be readily adapted to any system of crystal structures in which noncovalent interactions change as a function of any parameters. Employment of the title method along with quantum chemical calculations offers opportunities for the correlation of potential energy of crystalline materials with noncovalent interactions in their structures, which is a giant step forward towards a more complete understanding of the relationship between the structure and properties of compounds.

Uranyl Coordination Compounds with Alkaline Earth Metals and Crotonate Ligands

“…However, taking into account their different crystal structures one might expect different motifs of noncovalent interactions, as, for example, small charged mononuclear units in compound 1 should definitely pack in a different fashion in comparison with large neutral hexanuclear clusters in compounds 3 and 4 . To study noncovalent interactions in the title compounds we used the method of molecular VD polyhedra . The results of calculations are provided in Tables S3 and S4 in Supporting Information and in Figure .…”

“…1129, 914, 1701 and 1719 Å 2 for compounds 1–4 respectively. This area represents the total surface area of all independent molecular units in the crystal structure . The decreased surface area in compound 2 in comparison with compound 1 is explained with clustering – the total surface of multiple units is larger than the surface of the same units, but aggregated in a cluster, as some former inter molecular faces become intra molecular after clustering.…”

“…To study noncovalent interactions in the title compounds we used the method of molecular VD polyhedra. [46,47] The results of calculations are provided in Tables S3 and S4 in Supporting Information and in Figure 4. The fact that more than 95% of intermolecular interactions are due to H/H, H/C and H/O contacts is not surprising, as these atoms form the periphery of the building units (Figure 4a).…”

Plastically Bendable Crystals of Flufenamic Acid Form III

“…1a). The FFA has been widely investigated on the polymorphs, [30][31][32] crystal structure, [33][34][35][36] spectroscopy, [37][38][39] nucleation behavior 40 and tableting performance. 41 However, no one reported its plastic bending performance and explored its bending mechanism.…”

The phenomenon of polymorphism within the stereoatomic model of crystal structures

“…The (RF, d) distributions were introduced in assistance to the k-Φ criterion to get an idea of the relationship between the ranks of faces and the corresponding interatomic distances [5]. Also, a method was developed to visualize changes in noncovalent interactions when changing the geometry of molecules [7].…”