Study of the crystal structure, H-bonding and noncovalent interactions of novel cocrystal by systematic computational search approach

A novel cocrystal is designed based on the C-H center dot center dot center dot O, O-H center dot center dot center dot O hydrogen bonding interactions and characterized using single crystal X-ray diffraction method. The theoretical calculations, and the noncovalent interactions (NCI) were carried out to understand the structure-directing interactions in the cocrystal. C-H center dot center dot center dot O, C-H center dot center dot center dot N, and C-H center dot center dot center dot pi interactions further stabilised the crystal structure. The two-dimensional chain structure is formed by the C-H center dot center dot center dot pi, C-H center dot center dot center dot N and C-H center dot center dot center dot Cl interactions. The molecular interactions in the crystal structure were analysed by considering the intermolecular contacts using Hirshfeld surface methods. The density functional theory (DFT) calculations were performed to predict the molecular structure and related electrical and chemical properties. The small bandgap value (2.6245 eV) of the cocrystal signifies its high reactivity. The NBO analysis of the second-order perturbation theory indicated the pi*(C29-C16) -> pi*( C32-C31) (220.66 kcal/mol), pi*(C8-C9) -> pi*( C10-C1) (200.43 kcal/mol) and pi*(C21-C23) -> pi*(C24-C15) (199.04 kcal/mol) anti-bonding orbitals results in intramolecular charge transfer causing stabilisation of the cocrystal. The results obtained from the theoretical calculations are found to be consistent with the experimental crystal structures. The pattern of the noncovalent interactions has been extensively studied and quantified using the DFT computations coupled with the Bader analysis. The presence of the green regions in the interlayer regions obtained by the NCI plot signifies the importance of weak noncovalent interactions. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

A novel cocrystal based on hydrogen bonding interactions was designed and characterized using experimental and theoretical methods. The results showed that intramolecular charge transfer stabilizes the crystal structure, and weak noncovalent interactions play an important role in the crystal structure.