Application of the method for visualization of noncovalent interactions in conformational polymorphs of four organic acids

A method for the visualization of noncovalent interactions using examples of the conformational polymorphs of four organic compounds: 2-(phenylamino)nicotinic, 2-(3-chloro-2-methylphenylamino)nicotinic, N-(3-chloro-2-methyl-phenyl)anthranilic and 2-(methylphenylamino)nicotinic acids is examined. The changes in noncovalent contacts are plotted against the angle between the planes of aromatic rings allowing a visual representation of conformational adjustment of molecules as well as packing features of crystal structures. According to the k-Phi criterion, the studied structures represent conformational polymorphs. Different types of hydrogen bonding are discussed within the framework of the method of visualization and molecular Voronoi-Dirichlet polyhedra. Good correlations are found between calculated and experimental data for several cases, such as the agreement between pi stacking and polymorphic transition temperatures as well as between the area of a contact and the energy of conjugation. Also, an attempt has been made to assess the relative contributions of conformational and packing polymorphism in the formation of polymorphs.

Automated summary

This study examines a method for visualizing noncovalent interactions using examples of conformational polymorphs of four organic compounds. The method plots changes in noncovalent contacts against the angle between the planes of aromatic rings, providing a visual representation of molecular conformational adjustment and crystal packing features. The studied structures represent conformational polymorphs according to the k-Phi criterion. The method discusses different types of hydrogen bonding using molecular Voronoi-Dirichlet polyhedra and shows good correlations between calculated and experimental data in various cases.