Spectral, XRD, morphological, DFT, and molecular modeling investigations of newly prepared isatin Schiff base complexes

Abstract

The new Schiff base ligand was designed from a condensation reaction of isatin with 5‐amino‐2‐hydroxy benzoic acid. Then, the metal complexes were prepared. The structures of the prepared compounds were framed from thermogravimetric analyses (TG–DTG), mass spectrometry, elemental analyses, 1H‐NMR, IR, electronic spectra, UV–vis, and conductivity measurements. Surface and size morphology have been studied by X‐ray powder diffraction and scanning electron microscope (SEM) analysis. The IR spectra suggested that the ligand acted as bidentate coordinated with metal ions through deprotonated carboxylate oxygen atom and oxygen of phenolic group. With the exception of the complexes of Cr (III), Fe (III), and Cd (II), which were non‐electrolytes, the molar conductivities demonstrated the electrolytic behavior of all the rest complexes. The X‐ray diffraction (XRD) analysis patterns for the Schiff base complexes indicated their crystalline nature except the Co (II) complex which had amorphous structure. The ligand and its metal complexes were screened for their antimicrobial activities against two G‐positive, two G‐negative bacteria and against Aspergillus fumigatus and Candida albicans fungi. Additionally, the compounds were evaluated against the MFC‐7 breast cancer cell line for their anticancer activity. The outcomes demonstrated their strong antitumor activity. [Fe(HL)Cl2(H2O)2]0.5H2O complex has the lowest IC50 value = 9 μg mL−1. Molecular modeling studies for the ligand and its Co (II) and Fe (III) complexes were accomplished from density functional theory (DFT) analysis. From molecular docking study, the electrophilic moieties in both complexes displayed good binding interactions with the CDK6, aminoglycoside phosphotransferase, and CYP51 targeted proteins.