Synthesis, spectroscopic investigation, theoretical insights via DFT and biological assessment of some isatin-based metal complexes

In this work, new VO2+, Ni2+ and Cu2+ complexes (1–3), respectively, were synthesized from indoline-2,3-dione with 4,4′-diaminodiphenyl ether. The metal complexes were characterized using elemental analyses (C, H, and N), Fourier transform infrared (FT-IR), UV–Visible spectra, thermogravimetric analysis methods,1H-NMR spectrum, molar conductivity and magnetic susceptibility measurements. The findings showed a square pyramidal geometry around the VO2+ complex, tetrahedral and distorted square planar environments around the Ni2+ Cu2+ complexes. Density functional theory (DFT) calculations were performed to elucidate the geometrical and energetic properties of the ligand and its metal complexes. In vitro antidiabetic property of the synthesized ligand and its metal chelates (1–3) was estimated by α-amylase inhibition method. Investigating the compounds’ in vitro anticancer potential against the hepatic cancer cell lines (HepG-2) and against human lung fibroblast normal cell line (WI-38) was reported. The results showed that VO2+ complex possesses the highest ability to inhibit α-amylase as well as hepatic cancer cells. In light of this, VO2+ complex (1) that was synthesized has the potential to be utilized as possible candidates for antidiabetic and hepatic cancer treatment. The in-vitro antibacterial efficacy of the synthesized ligand and its metal complexes (1–3) was assessed against both two Gram-positive bacteria (B. subtilis and S. aureus) and two Gram-negative bacteria (E. coli and K. pneumonia). Cu2+ chelate showed the highest activity against the tested microbes.