X-ray structures, spectroscopic, antimicrobial activity, ESP/HSA and TD/DFT calculations of Bi(III) complex containing imidazole ring

A novel complex [Bi(L)2(NO3)3] (L = 2-(4-imidazolyl)-4-methyl-1,2-dihydroquinazoline-N3-oxide) was synthesized via complexation of the quinazoline ligand L with Bi(III) nitrate pentahydrate in methanol and ethyl acetate. The structure of complex was determined by elemental analysis, FT-IR, UV–vis and fluorescence spectroscopy, as well as characterized by X-ray crystallography. Crystallographic analysis divulged that the central atom Bi(III) was coordinated with eight atoms and the ratio of ligand-to-metal was 2:1. Specially, it fostered into an infinite 1-D chain, 2-D layered and ladder-like 3-D supramolecular skeleton through different intermolecular interactions. In addition, the fluorescence behaviors of Bi(III) complex in six solvents of diverse polarities were quite different. The DFT/B3LYP theoretical level has been successfully applied to calculate the optimized geometry, electronic distribution of HOMO-LUMO and the electrostatic potential diagram of Bi(III) complex. Meanwhile, the electronic transitions recorded by TD/DFT calculation theoretically rationalized the UV–vis spectrum data. The antibacterial activity of Bi(III) complex against Escherichia coli and Staphylococcus aureus were further studied. Plausible non-covalent interactions were quantified using Hirshfeld surfaces and 2D fingerprint plots.