Designing of novel nano-sized coordination compounds based on Spinacia oleracea extract: Synthesis, structural characterization, molecular docking, computational calculations, and biomedical applications

A novel series of nano-sized metal chelates of 1-((E)-(2-mercaptophenylimino)methyl)naphthalen-2-ol (H2L) Azo-methine ligand with Fe(III), Ni(II) and Ag(II) were prepared and investigated for antitumor activities. The structures of all the synthesized compounds have been analyzed using various physicochemical techniques. The results showed a distorted square-planar geometry for Ni2L2 and AgL, whereas the geometry around the FeL complex is octahedral. The nano-sized Fe and Ag complexes were prepared in an easy, rapid and eco-friendly way using Spinacia oleracea (SO) extract in EtOH. X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV.Vis. spectra were used to assess the structural characteristics and particle size of the newly produced nano-sized Fe and Ag complexes. Furthermore, from TGA, we investigated the impact of heat on the particle size of newly prepared compounds. The geometry optimization of the prepared complexes and various quantum chemical parameters were computed by Gaussian 09 softwares. The results showed that all of the metal complexes studied are more stable than the free ligand H2L, with the Ni2L2 complex being the most stable. All microand nano-complexes were tested for in vitro anticancer activities, and the results revealed inhibition of cancer cell activity, although the smaller size is better than the larger size. The liver cancer and COVID-19 were screened using molecular docking to determine the possible binding energy of inhibitors.