Polymorphism of 2-(5-benzyl-6-oxo-3-phenyl-1,6-di-hydro-pyridazin-1-yl)acetic acid with two monoclinic modifications: crystal structures and Hirshfeld surface analyses

Synthesis, Spectroscopic Characterization, Antibacterial Activity, and Computational Studies of Novel Pyridazinone Derivatives

In this work, a novel series of pyridazinone derivatives (3-17) were synthesized and characterized by NMR (¹H and ¹³C), FT-IR spectroscopies, and ESI-MS methods. All synthesized compounds were screened for their antibacterial activities against Staphylococcus aureus (Methicillin-resistant), Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa, and Acinetobacter baumannii. Among the series, compounds 7 and 13 were found to be active against S. aureus (MRSA), P. aeruginosa, and A. baumannii with the lowest MIC value range of 3.74-8.92 µM. Afterwards, DFT calculations of B3LYP/6-31++G(d,p) level were carried out to investigate geometry structures, frontier molecular orbital, molecular electrostatic potential maps, and gap energies of the synthesized compounds. In addition, the activities of these compounds against various bacterial proteins were compared with molecular-docking calculations. Finally, ADMET studies were performed to investigate the possibility of using of the target compounds as drugs.

Crystal structure and Hirshfeld surface analysis of 6-((E)-2-{4-[2-(4-chloro-phen-yl)-2-oxoeth-oxy]phen-yl}ethen-yl)-4,5-di-hydro-pyridazin-3(2H)-one

The pyridazine ring in the title compound, C20H17ClN2O3, adopts a screw-boat conformation. The whole mol-ecule is flattened, the dihedral angles subtended by the least-squares plane of the central aromatic ring with those of the terminal benzene and pyridazine rings being 15.18 (19) and 11.23 (19)°, respectively. In the crystal, the mol-ecules are linked by pairs of N-H⋯O bonds into centrosymmetric dimers and by C-H⋯π contacts into columns. The results of the Hirshfeld surface analysis show that the most prominent inter-actions are H⋯H, accounting for 36.5% of overall crystal packing, and H⋯O/O⋯H (18.6% contribution) contacts.

Crystal structure and Hirshfeld surface analysis of 4-(2,6-di-chloro-benz-yl)-6-[(E)-2-phenyl-ethen-yl]pyridazin-3(2H)-one

The title pyridazinone derivative, C19H14Cl2N2O, an important pharmacophore with a wide variety of biological applications is not planar, the chloro-phenyl and pyridazinone rings being almost perpendicular, subtending a dihedral angle of 85.73 (11)°. The phenyl ring of the styryl group is coplanar with the pyridazinone ring [1.47 (12)°]. In the crystal, N-H⋯O hydrogen bonds form inversion dimers with an R 2 2(8) ring motif and C-H⋯Cl hydrogen bonds also occur. The roles of the inter-molecular inter-actions in the crystal packing were clarified using Hirshfeld surface analysis, and two-dimensional fingerprint plots indicate that the most important contributions to the crystal packing are from H⋯H (37.9%), C⋯H/H⋯C (18.7%), Cl⋯H/ H⋯Cl (16.4%) and Cl⋯C/C⋯Cl (6.7%) contacts.