Novel zinc (II) and nickel (II) complexes of a quinazoline-based ligand with an imidazole ring: Synthesis, spectroscopic property, antibacterial activities, time-dependent density functional theory calculations and Hirshfeld surface analysis

Two complexes [Zn(L)(2)(CH3OH)(2)](NO3)(2) (1) and [Ni(L)(3)]center dot(NO3)(2) (2) (L = 2-[2-imidazolyl]-4-methyl-1,2-dihydroquinazoline-N-3-oxide) were obtained successfully by means of slow evaporation solution technique (SEST) and characterized using elemental analysis, FT-IR, UV-vis, and fluorescence spectroscopic. X-ray diffraction revealed that the metal in complex 1 is chelated by two L ligands and two lattice methanol molecules, whereas in 2 by three L ligands, counterbalanced by nitrate ions. The crystal structures of both showed infinite 1-D, 2-D, and 3-D supramolecular architecture due to intermolecular interactions. Most strikingly, Zn (II) complex showed different fluorescence properties in diverse solvents. The antimicrobial activities of all compounds were compared and showed perceptible efficiency against Gram-negative and Gram-positive bacteria. Electrostatic potential (ESP) calculation was used to predict the nucleophilic and electrophilic attack sites. Density functional theory (DFT) calculation results showed good agreement with experimental data, as well as the frontier molecular orbital energy gaps were detected by time-dependent (TD)-DFT method with HOMO-LUMO calculations. Additionally, the non-covalent interactions of both complexes were further quantified and explored with the help of Hirshfeld surface analysis.

Automated summary

Two complexes with different fluorescence properties were successfully synthesized and showed significant antibacterial activities. The agreement between experimental and DFT calculation results was confirmed, and non-covalent interactions of the complexes were further explored using Hirshfeld surface analysis.