Cocrystal screening of benznidazole based on electronic transition, molecular reactivity, hydrogen bonding, and stability

Screening of cocrystals of active pharmaceutical ingredients is important in the development of pharmaceutical compounds because it improves bioavailability, stability, solubility, and many other physicochemical properties. In this work, quantum chemical calculations were utilized for the computational evaluation of the cocrystal screening of benznidazole (BZN) API via hydrogen bonding with four coformers (maleic acid, malonic acid, oxalic acid, and salicylic acid), and they contain carboxylic groups. The nitrogen of the imidazole ring in benznidazole and the carboxylic group of the coformer form a hetero-synthon connected by a strong hydrogen bond. The strength of the hydrogen bonding interaction O–H…N was measured using various tools. It was found that in comparison to BZN cocrystals with malonic acid, oxalic acid, and salicylic acid, the O–H…N interaction in the BZN-maleic acid cocrystal had higher interaction energy, indicating it had stronger hydrogen bonding. The strength of the hydrogen bond O–H…N for synthons was discovered to be more beneficial than the C–H…O interaction, as confirmed by ESP analysis. The BZN-salicylic acid cocrystal was found to be more reactive and polarizable, whereas the BZN-malonic acid cocrystal was more stable. Cocrystals of benznidazole exhibited better physicochemical characteristics than API benznidazole, as indicated by electron transition properties between the most significant orbitals.

The computational evaluation for the screening of benznidazole cocrystals was performed in Gaussian 16 software using density functional theory (DFT) with the hybrid functional B3LYP and the basis set 6–311 +  + G(d,p). The UV–Vis absorption spectrum in solvent water was analyzed using the TD-DFT/6–311 +  + G(d,p) method to determine the influence of the solvent in cocrystals using a polarizable continuum model. The strength of the hydrogen bonding interactions O–H…N in each of those mentioned cocrystals was used to screen the cocrystals using tools such as thermodynamic probability, ESP analysis, QTAIM analysis, and NBO analysis. The pairing energy of interaction was measured by determining H-bond donor ( \({\alpha }_{\text{max}}\) ${\alpha }_{\text{max}}$ ) and H-bond acceptor \({(\beta }_{\text{max}}\) ${(\beta }_{\text{max}}$ ) parameters for hydrogen bonds from maxima and minima on the ESP surface. GaussView 06 software was used to create, visualize, and plot the optimized structure of the cocrystal and HOMO–LUMO orbitals. The AIMALL (10.05.04) software package generated the molecular graph for intra- and intermolecular interactions. The RDG-scatter plot, MEP map, and ELF plot were rendered from Multiwfn 8.0 and VMD 1.9.1 software.