FACILE AND GREEN SYNTHESIS, CRYSTAL STRUCTURE, ANTIBACTERIAL ACTIVITY, HIRSHFELD SURFACE ANALYSIS, AND COMPUTATIONAL INVESTIGATION OF A NOVEL LITHIUM(I) COMPLEX: COMPARISONS OF THEORETICAL AND EXPERIMENTAL ANALYSES

Abstract

A novel monovalent lithium complex, [Li(C6H4NO3)(H2O)2] (1), was prepared via a simple one-pot green reaction of 2-hydroxypyridine-3-carboxylic acid (2-hpca) with lithium carbonate and aminoguanidine (Amgu) bicarbonate in water. Complex 1 was investigated using elemental, ultraviolet–visible, Fourier transform infrared (FT-IR), thermal, and single-crystal X-ray diffraction (SC-XRD) measurements. We found that 1 crystallized in the monoclinic C2/m space group with a = 12.800(2) Å, b = 6.6657(13) Å, and c = 9.4687(19) Å. The Li ion exhibited four coordinates with a distorted square planar geometry. That is, the ion was surrounded by four oxygen atoms, of which two were derived from two water molecules, one was from the carboxylate group, and one was from the keto group of the 2-oxo-1,2-dihydropyridine-3-carboxylate ligand. Simultaneous thermogravimetry–differential thermal analysis of 1 exhibited dehydration followed by continuous low-temperature (∼400 °C) decomposition to produce lithium oxide as the end product in an air atmosphere. Furthermore, density functional theory (DFT) analysis was conducted to compare the theoretical and experimental data collected via SC-XRD. In addition, DFT was used to analyze the frontier molecular orbital energy levels and energy gaps. Moreover, we conducted Hirshfeld surface studies with respect to 1 to differentiate between the intermolecular hydrogen bond contacts. Energy frameworks for 1 were produced by analyzing the energy interactions between intermolecular hydrogen bonds to investigate the prevailing interactions involved in molecular packing. The in silico results showed that 1 has high potential for the development of antimicrobial drugs. Molecular docking studies were also conducted to determine the binding energy of 1 with Staphylococcus aureus (5CZZ) and Escherichia coli (3T88). The results were consistent with the experimental data obtained from the antibacterial activity of 1 with respect to Staphylococcus aureus and Escherichia coli.