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[Display omitted] • Synthesis of new FePBZPHA, CoPBZPHA, and NiPBZPHA mixed-ligand complexes. • Stoichiometry determination confirming the 1:1:1 (M: PBZ: PHA) ratio; FT-IR spectra comparison elucidating intricate binding modes. • DFT calculations unveiling octahedral coordination geometries and enhanced electron affinity, electronegativity, and reactivity of metal complexes. • Biological evaluation showcasing significantly enhanced efficacy of metal complexes in antimicrobial, anti-inflammatory, and antioxidant activities, with FePBZPHA exhibiting the highest potency. • Molecular docking analysis highlighting potential therapeutic applications, with metal complexation enhancing binding affinity and interaction versatility. This study presents a thorough investigation into the synthesis, characterization, computational analysis, and biological evaluation of FePBZPHA, CoPBZPHA, and NiPBZPHA mixed-ligand complexes. They were synthesized in high yields via reactions between chloride salts of Iron, Cobalt, or Nickel with 2-(pyridin-2-yl)-1H-benzimidazole (PBZ) and Phenylalanine (PHA). They underwent extensive spectroscopic, elemental, conductivity, magnetic, and thermal analysis to confirm their formation. Molar conductivity measurements indicated their non-electrolytic nature, with UV–vis spectra revealing distinct absorption bands for PBZ and PHA ligands, shifting significantly upon metal ion coordination. Stoichiometry determination confirmed the 1:1:1 (M:PBZ:PHA) ratio, while FT-IR spectra comparison elucidated intricate binding modes, supported by mass spectra and elemental analysis. Thermal analysis revealed their thermal stability and decomposition pathways. DFT calculations unveiled octahedral coordination geometries and enhanced electron affinity, electronegativity, and reactivity of metal complexes. Biological evaluation showcased significantly enhanced efficacy of metal complexes in antimicrobial, anti-inflammatory, and antioxidant activities, with FePBZPHA exhibiting the highest potency. Molecular docking analysis highlighted their potential as therapeutic agents, with metal complexation enhancing binding affinity and interaction versatility. Overall, this study provides comprehensive insights into the synthesis, characterization, computational analysis, and biological evaluation of FePBZPHA, CoPBZPHA, and NiPBZPHA mixed-ligand complexes, suggesting promising applications in biomedicine and materials science. [ABSTRACT FROM AUTHOR]

The exploration encompassed the synthesis and characterization of two innovative complexes, namely FePHNS and CuPHNS, employing a diverse array of analytical techniques such as elemental analysis, infrared and ultraviolet-visible spectroscopy, mass spectrometry, molar conductivity measurements, magnetic susceptibility assessments, and thermal analysis (TGA). In the spectral domain, infrared spectroscopy substantiated the tridentate ONS coordination of the PHNS ligand to the central metal atom. Thermal analysis offered valuable insights into the distribution and content of water molecules within the complexes. Density functional theory (DFT) calculations were harnessed to validate the molecular structures of both the PHNS ligand and its complex entities, providing an intricate comprehension of their quantum chemical parameters. The investigation extended to an evaluation of the in vitro antibacterial, antifungal, and antioxidant efficacy of the PHNS ligand and its complexes, revealing heightened biological activities for the complexes in comparison to the free PHNS ligand, notably with the CuPHNS complex demonstrating the highest activity, while the PHNS ligand exhibited the lowest. To delve into potential physiological activities, molecular docking studies were conducted, predicting the binding affinity of the compounds to proteins 2vf5 (Glucosamine-6-phosphate synthase in complex with glucosamine-6-phosphate) from Escherichia coli, 3cku (rate oxidase from Aspergillus flavus complexed with its inhibitor 8-azaxanthin and chloride) from Aspergillus flavus, and 5IJT (Crystal structure of Human Peroxiredoxin 2 Oxidized). The ensuing analysis of protein-ligand interactions and binding energies underscored the promising physiological activities of the investigated compounds, warranting further exploration for their potential in novel drug development. [Display omitted] • Novel Fe(III) and Cu(II) ions in molar ratios of 1:1 and 1:2 with PHNS ligand complexes have been synthesized. • Their in vitro antibacterial, antifungal, and antioxidant efficacy of the PHNS ligand and its complexes has been investigated. • The CuPHNS complex demonstrated the highest biological activity, while the PHNS ligand exhibited the lowest. • DFT and molecular docking results were correlated with in vitro activities [ABSTRACT FROM AUTHOR]

Herien, three new Fe(III) (FeAZD), Ni(II) (NiAZD), and Cu(II) (CuAZD) complexes were synthesized and characterized using various physicochemical and spectroscopic approaches. The H 2 AZD ligand acted as a bi-basic bi-dentate NO ligand in a 1:1 molar ratio. The results revealed that the FeAZD and CuAZD complexes had octahedral geometry, while the NiAZD had a tetrahedral geometry. The optimized geometry, HOMO and LUMO analysis of the ligand and its metal complexes was determined via Density functional theory (DFT) using the B3LYP with 6–311 G(d,p), and LanL2DZ level of theory. The FeAZD, NiAZD and CuAZD had lower energy gap, 7.40, 7.93 and 7.06 eV, respectively, than the free ligand (9.58 eV), which proposed that CuAZD was more active one. The free ligand and its metal complexes were in vitro investigated for their antibacterial and antifungal activity. The results illustrated that the metal complexes had higher antibacterial and antifungal activity than the free ligand. More specifically, the CuAZD demonstrated good antibacterial activity against E. coli , P. aeruginosa , S. aureus, B. cereus , and A. flavus , T. rubrum , and C. albicans , with activity indexes of 72.22%, 65.01%, 77.78%, and 72.22%, 63.16%, 59.09%, and 61.90%, respectively. Also, the metal complexes showed lower MIC (6.25–3.125 ppm) compared to the free ligand (about 50 ppm). Finally, molecular docking was utilized to investigate the ability of the free ligand and its metal complexes to inhibit the growth of E. coli (PDB ID: 5iq9). The results showed that the CuAZD had the highest binding affinity to the receptor, with a more negative docking score of − 7.05 Kcal/mol, and lower inhibition constant (Ki) of 6.90 µM. That is indicating that it may be the most effective at inhibiting the growth of E. coli (PDB ID: 5iq9). [Display omitted] • Three FeAZD, NiAZD, and CuAZD complexes were synthesized and characterized. • The complexes had a more promising antimicrobial than the free ligand. • High ability of metal complexes to inhibit the growth of E. coli (PDB ID: 5iq9). • Positive results proposed various medicinal purposes for these compounds. [ABSTRACT FROM AUTHOR]

[Display omitted] A new Schiff-base ligand, 4-[(4-oxo-4,5-dihydro-1,3-thiazol-2-yl)hydrazono]methylphenyl 4-methylbenzenesulfonate (L), and its Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) complexes were synthesized and characterized. Elemental analysis, NMR spectroscopy, mass spectra, FT-IR analysis, molar conductivity, magnetic susceptibility tests and electronic spectra (UV-vis.) were all used to describe the ligand and its metal complexes. The complexes of Ni(II) and Zn(II) were found to have a tetrahedral structure, whereas those of Fe(III), Co(II) and Cu(II) exhibited an octahedral structure. The geometry of the ligand and its metal complexes was investigated by density functional theory (DFT) calculations at the B3LYP/6-311G(d, p) and LanL2dz levels of theory, respectively. To round out the picture, we evaluated not only the overall energy but also the HOMO and LUMO molecular orbitals and the molecular electrostatic potential (MEP). The synthetic analogues were tested for their in vitro antibacterial and antifungal efficacy against various pathogens using the disc diffusion method. The research shows that the metal complexes are more effective against these diseases than the free ligand. In addition, the DPPH method was used to measure the antioxidant activity in vitro. The antioxidant activity of each complex was higher than that of its free corresponding ligand. Molecular docking was carried out to determine the interactions between the complexes and the probable binding sites of Human Peroxiredoxin 2 Oxidized (PDB ID: 5IJT) and Escherichia coli (PDB ID: 3t88) receptors. [ABSTRACT FROM AUTHOR]

• New Fe complexes based on Schiff-base & N-heterocyclic ring have been assembled. • DFT calculations were performed to estimate the electronic properties. • The complexes showed a promising antibacterial and antifungal activity. • Phenoxazinone synthase mimicking activity was explored. • Structure activity relationship (SAR) for these complexes had been derived. New Fe(III) complexes with mixed ligands based on 1-{(E)-[(4-methylphenyl)imino]methyl}-2-naphthol (HN) as primary ligand and secondary co-ligand of O-hydroxy quinolone (HQ), 2-(1H-benzimidazol-2-yl)phenol (HB) and 2-(4,5-diphenyl-1H-imidazol-2-yl)phenol (HI) had been isolated and characterized. The isolated complexes had 1:1:1 ratio for Fe(III):ligand:co-ligand with one chloride and one water molecule coordinated to the Fe-centre, suggesting octahedral structure around the Fe-center with the formula [Fe(Ligand)(co-ligand)(Cl)(H 2 O)]. Theoretical calculations using density functional theory by B3LYP with LANL2DZ basis set had been done for two possible orientations of the ligand moieties around the Fe-center, to find out the most reliable coordination modes. Calculations include geometry optimization, molecular orbital description, and energy evaluation of trans- and cis-coordination modes of the chloride and water around the Fe-center. In-vitro antibacterial and antifungal properties of the isolated complexes have also been examined against pathogenic bacteria, E. coli (G−), B. cereus (G+), and A. fumigatus fungi, by using broth microdilution and disc diffusion methods. The target compounds exhibited considerable growth inhibition against selected pathogenic microorganisms as antimicrobial candidates with low minimum inhibitory concentration (MIC). The complexes showed biomimetic phenoxazinone synthase-like activity for the aerial coupling oxidation of o-aminophenol (OAP) to phenoxazine-2-one (Phz), in acetonitrile (ACN) solution, with high turnover number (K cat). Structure Activity Relationship (SAR) model was derived, using Multi-Linear Regression analysis, by correlation the practical biological (MIC) data with calculated chemical descriptors. [ABSTRACT FROM AUTHOR]