Ni(II), Co(II), Fe(III), and Zn(II) mixed ligand complexes of indoline-dione and naphthalene-dione: Synthesis, characterization, thermal, antimicrobial, and molecular modeling studies

New mixed ligand complexes with metal ions (Ni(II), Co(II), Zn(II), and Fe(III)) of the type [ML1L2] (where L1 = indoline-2,3-dione and L2 = naphthalene-1,2-dione) were synthesized and characterized using elemental analyses, molar conductivity, spectroscopic (IR, UV–visible, diffused reflectance), magnetic moment, and thermal studies. Mass spectra for [Co(L1L2)(H2O)2]Cl2, [Ni(L1L2)(H2O)2]Cl2, [Fe(L1L2) (H2O)2]Cl3 and [Zn(L1L2)(H2O)2]Cl2 complexes were studied. The IR spectral data revealed that L1 and L2 ligands behaved as neutral bidentate ligands with OO donation sites (indoline O and naphthalene-dione O for L1 and L2). An octahedral geometry for the complexes was proposed based on spectroscopic data. The thermogravimetric study was used to look into the metal complexes temperature stability and deterioration. The Co(II), Zn(II), Ni(II), and Fe(III) complexes' SEM and XRD spectra were also obtained. Theoretical investigation of Zn(II) complex was performed with the DFT-B3LYP computational method. DFT calculations better understand molecular mechanisms that could not be elucidated experimentally where the energy gaps and other key theoretical parameters were calculated. The vina dock mechanisms and affinities of Zn(II) complexes for E. coli (PDB ID: 3 t88), S. aureus (PDB ID: 3ty7), B. subtilis (PDB ID: 5 h67), and P. aeruginosa (PDB ID: 5i39) receptors were also investigated. The mixed ligand complexes were evaluated for antibacterial efficacy against two species of Gram-positive and Gram-negative bacteria and fungi. All the complexes inferred antimicrobials activity against the studied organisms which make them promising drugs.