Exploring Polymorphism and Diversity in Intermolecular Interactions in Substituted Crystalline Benzophenones

A detailed experimental investigation of the supra-molecular features of the structural assembly and a quantitative evaluation of the various intermolecular interaction energies were performed for a total of six substituted crystalline benzophenones. Among these, two compounds, namely, 2-fluoro-4'-hydroxybenzo-phenone (2F4'HBZP) and 2-chloro-5-nitro benzophenone (2C5NBZP), were found to exist as concomitant dimorphs due to their conformational flexibility with respect to the carbonyl and phenyl groups. The remaining four compounds, namely, 3-fluorobenzophenone (3FBZP), 4-fluoro-4'-hydroxy benzophenone (4F4'HBZP), 2,4'-dichloro benzophenone (2C4'CBZP), and 4,4'-dichloro-3-nitro benzophenone (4,4'C3NBZP), exist as monomeric forms. Crystal packing analysis revealed the relevance of weak hydrogen bond interactions like C-H center dot center dot center dot O (with nitro and carbonyl group as hydrogen bond acceptors), C-H center dot center dot center dot F, C-H center dot center dot center dot pi, and pi center dot center dot center dot pi interactions along with halogen bond interactions in the absence and presence of strong hydrogen bonds, like O-H center dot center dot center dot O=C, respectively. Furthermore, the quantitative interplay of electrostatic, dispersive, and repulsive contributions to the interaction energies was explored on account of the variation in the substituents on the phenyl rings in benzophenones via PIXEL calculations.