Synthesis and characterization of Schiff base octaazamacrocyclic complexes and their biological studies

Metal complexes featuring a quinazoline schiff base ligand and glycine: synthesis, characterization, DFT and molecular docking analyses revealing their potent antibacterial, anti-helicobacter pylori, and Anti-COVID-19 activities

Mixed ligand complexes of manganese(II), cobalt(II), copper(II), and cadmium(II)with an innovative Schiff base ligand denoted as (L1), 4-(2-((1E,2E)-1-(2-(p-tolyl)hydrazineylidene)propan-2-ylidene)hydrazineyl), served as the principal ligand, while glycine (L2) was employed as secondary ligand were successfully effectively characterized through a comprehensive set of analyses, including Elemental analysis, UV-Visible, FT-IR, Mass spectra, and conductometric measurements. Density functional theory (DFT) computations were executed to discern the enduring electronic arrangement, the energy gap, dipole moment and chemical hardness of the hybrid ligand assemblies. The proposed geometry for the complexes is a distorted octahedral structure. The antimicrobial efficacy of these compounds was assessed against a range of bacterial and fungal strains. Notably, these complexes exhibited promising antimicrobial activities, with the cadmium (II) complex demonstrating superior efficacy towards all tested organisms. These compounds were also examined for their antibiotic properties against H. pylori to explore their broader medical potential. The Schiff base ligand and its corresponding metal complexes displayed substantial potential as an antibiotic against H. pylori. Additionally, the antitumor potential of the synthesized complexes was assessed against MCF-7 (Breast carcinoma) cells-the Cu (II) complex demonstrated superior activity with the lowest IC50 value compared to cisplatin. Moreover, it exhibited reduced cytotoxicity towards normal cells (VERO cells) compared to cisplatin, establishing it as the most potent compound in the study. Furthermore, molecular docking was explored of the Schiff base ligand and its corresponding cadmium(II) complex. The analysis of the docking study yielded valuable structural insights that can be effectively utilized in conducting inhibition studies for example against COVID-19. This comprehensive study highlights these synthesized compounds' multifaceted applications and promising bioactive properties.

Triazole based Schiff bases and their Oxovanadium(IV) complexes: Synthesis, characterization, antibacterial assay, and computational assessments

The synthesis and characterization of two new Schiff base ligands containing 1,2,4-triazole moieties and their oxovanadium(IV) complexes have been reported. The ligands and their complexes were studied by ultraviolet-visible (UV-Vis), Fourier transform infrared (FTIR), proton nuclear magnetic resonance (¹H NMR), electron paramagnetic resonance (EPR), X-ray diffraction (XRD), conductivity measurement, cyclic voltammetry (CV), and elemental analyses. The molar conductance of oxovanadium(IV) complexes were found to be relatively low, depicting their non-electrolytic nature. The XRD patterns reveal the size of particles to be 47.53 nm and 26.28 nm for the two complexes in the monoclinic crystal system. The molecular structures, geometrical parameters, chemical reactivity, stability, and frontier molecular orbital pictures were determined by density functional theory (DFT) calculations. The theoretical vibrational frequencies and EPR g-factors (1.98) were found to correlate well with the experimental values. A distorted square pyramidal geometry with C₂ symmetry of the complexes has been proposed from experimental and theoretical results in a synergistic manner. The antimicrobial sensitivity of the ligands and their metal complexes assayed in vitro against four bacterial pathogens viz. Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Salmonella Typhi showed that the oxovanadium(IV) complexes are slightly stronger antibacterial agents than their corresponding Schiff base precursors. The binding affinities obtained from the molecular docking calculations with the receptor proteins of bacterial strains (2EUG, 3UWZ, 4GVF, and 4JVD) showed that the Schiff bases and their oxovanadium(IV) complexes have considerable capacity inferring activeness for effective inhibition. The molecular dynamics simulation of a protein-ligand (4JVD-HL₂) complex with the best binding affinity of -12.8 kcal/mol for 100 ns showed acceptable stability of the docked pose and binding free energy of -15.17 ± 2.29 kcal/mol from molecular mechanics-generalized Born surface area (MM-GBSA) calculations indicated spontaneity of the reaction. The outcome of the research shows the complementary role of computational methods in material characterization and provides an interesting avenue to pursue for exploring new triazole based Schiff's bases and its vanadium compounds for better properties.

Synthesis, Characterization, Computational and Biological Activity of Some Schiff Bases and Their Fe, Cu and Zn Complexes

Four new symmetrical Schiff bases derived from 2,2′-diamino-6,6′-dibromo-4,4′-dimethyl-1,1′-biphenyl or 2,2′-diamino-4,4′-dimethyl-1,1′-biphenyl, and 3,5-dichloro- or 5-nitro-salicylaldehyde, were synthesized and reacted with copper-, iron- and zinc-acetate, producing the corresponding complexes. The Schiff bases and their metal complexes were characterized by 1H-, 13C-NMR, IR and UV-Vis spectroscopy and elemental analysis. The structures of one Schiff base and the two zinc complexes were resolved by X-ray structure determination. Density functional theory (DFT) calculations at the B3LYP/6-31G(d) level of the latter compounds were carried out to optimize and examine their molecular geometries. The biomedical applications of the Schiff bases and their complexes were investigated as anticancer or antimicrobial agents.

Unraveling the Pharmaceutical Benefits of Freshly Prepared Amino Acid-Based Schiff Bases Via DFT, In Silico Molecular Docking and ADMET

A series of amino acid-based Schiff bases have been synthesized using a facile condensation between benzil (a diketone) and amino acid in the presence of a base. The formation of Schiff base compounds has been ensured by elemental analysis, FT-IR, ¹H-NMR, ¹³C-NMR and UV-Vis. spectra. Density Functional Theory (DFT) calculations have been explored in order to get intuition into the molecular structure and chemical reactivity of the compounds. The DFT, optimized structure of the compounds, has been used to attain the molecular docking studies with DNA structure to find the favorable mode of interaction. In silico ADME/Tox profile of the compounds has been predicted using pkCSM web tools, exhibiting suitable values of absorption, distribution, and metabolism. These obtained parameters are connected to bioavailability. In addition, toxicity, skin sensitization and cardiotoxicity (hERG) analysis have been performed for evaluating the drug-like character of the prepared Schiff bases. The findings obtained from this study may find applications in the field focusing on the production of efficient and harmless pharmacological drugs.

Spectroscopic, SOD, anticancer, antimicrobial, molecular docking and DNA binding properties of bioactive VO(IV), Cu(II), Zn(II), Co(II), Mn(II) and Ni(II) complexes obtained from 3-(2-hydroxy-3-methoxybenzylidene)pentane-2,4-dione

Novel macrocyclic Schiff base complexes [[ML]X; where M = Cu(II), Co(II), Ni(II), Zn(II), Mn(II) and VO(IV)^; L = macrocyclic ligand; X = Cl₂ and SO₄^2-] have been synthesized and characterized by microanalytical, ¹H, ¹³C NMR, IR, Mass, UV-Vis, EPR spectral studies, as well as conductivity data. All the complexes exhibit square-planar geometry except vanadium complex. Magnetic susceptibility measurements and high conductance data reveal the monomeric and electrolytic nature of the complexes. Electronic absorption, cyclic voltammetry, viscosity measurements have been carried out on the interaction of the complexes with DNA. The results suggest that the complexes bind to DNA by intercalation via the aromatic ring of the macrocycle into the base pairs of DNA. Using gel electrophoresis experiment in the presence and absence of oxidant (H₂O₂) the nuclease cleavage activity of the complexes has been performed on plasmid DNA. The results demonstrate that most of the complexes have promising superoxide dismutase (SOD)-mimetic activity. The in vitro cytotoxicity of ligand and its complexes has also been evaluated against human breast and colon carcinoma cells. Binding interactions and energies of ligand and its metal complexes [ML]²⁺ (M = VO(IV), Mn(II), Co(II), Ni(II), Cu(II), Zn(II)) against the receptors EGFR and HER2 are performed using the Auto dock module. Consequently, it is found that the ligand is strong inhibitor for EGFR and HER2 while [VOL]SO₄ is good inhibitor for EGFR and [ZnL]Cl₂ is moderate inhibitor for HER2. The antimicrobial activity of the ligand and its complexes against bacteria Salmonella typhi, Staphylococcus aureus, Escherichia coli and Bacillus subtilis and fungi Aspergillus niger, Aspergillus flavus, Candida Albicans and Rhizoctonia bataicola. The complexes have higher activities than the macrocyclic free Schiff base. Interaction of [VOL]SO₄ to the binding sites of target protein EGFR (PDB ID: 4HJ0). Research HighlightsMacrocyclic Schiff base and its metal complexes were synthesized.Complexes bind to DNA by intercalation via the aromatic ring of the macrocycle into the base pairs of DNA.Vanadyl complex is a good inhibitor for EGFR.The complexes of copper, zinc and vanadium show efficient antitumor activity.Copper and vanadium complexes have superior antimicrobial activity than the standards.

Synthesis, Characterization, and Biological Evaluation of Unimetallic and Heterobimetallic Complexes of Bivalent Copper

We present an inclusive characterization of the unimetallic and heterobimetallic complexes of copper synthesized using CuCl₂ and diamine (4-fluoro 1,2-phenylenediamine) resulting in monometallic complex which further undergoes treatment with organometallic dichlorides of group 4 and 14 in 1 : 2 molar ratio resulting in heterobimetallic complexes. These complexes thoroughly characterized using various physical, analytical, and spectroscopic techniques indicate square planar and distorted octahedral geometry for the synthesized unimetallic and heterobimetallic complexes, respectively. These complexes were evaluated for their antimicrobial efficacy against various bacterial and fungal strains while hepatoprotective activity was also examined in male albino rats.

Techniques in the synthesis of mononuclear manganese complexes: a review

This article describes an overview of the synthetic techniques and protocols for the preparation of new ligands and respective manganese (Mn) complexes to be tested for biomedical applications. Mn is an essential and biocompatible element, the complexes of which have diverse medicinal applications. The most significant use of Mn complexes is their application against reactive oxygen species in biological systems, and due to this, three Mn-incorporated complexes (AEOL-10150, EUK-134, and M40403) are already under clinical trials. Hence, the interest in synthesizing biologically active Mn complexes is rapidly increasing. Mn complexes are commonly synthesized using either water or ethanol as a reaction medium for their possible usage in biological systems. Using common Mn salts along with suitable organic ligand works well in the presence of little heat to obtain Mn complexes of interest.

Herbo-mineral based Schiff base ligand and its metal complexes: Synthesis, characterization, catalytic potential and biological applications

Schiff base ligand, (L), derived from condensation reaction of 1,7-bis-(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione, (curcumin), with pyridine-3-carboxamide, (nicotinamide), and its complexes of Co(II), Ni(II) and Cu(II) ions, containing 1,10-phenanthroline as auxiliary ligand were synthesized and characterized by various physico-chemical techniques. From the micro analytical data, the stoichiometry of the complexes 1:1 (metal: ligand) was ascertained. The Co(II) and Cu(II) forms octahedral complexes, while the geometric structure around Ni(II) atom can be described as square planar. The catalytic potential of the metal complexes have been evaluated by recording the rate of decomposition of hydrogen peroxide. The results reveal that the percent decomposition of H2O2increases with time and the highest value (50.50%) was recorded for Co(II) complex. The ligand and its complexes were also screened for their in vitro antibacterial activity against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, Streptococcus pyogenes and Pseudomonas aeruginosa. The relative order of antibacterial activity against S. Pyogenes, S. aureus and E. coli is Cu(II)>Ni(II)>Co(II)>(L); while with P. aeruginosa, K. pneumoniae the order of activity is Cu(II)>Co(II)>Ni(II)>(L). The anthelmintic screening was performed using Pheretima posthuma. The order of anthelmintic activity of ligand and its complexes is [(Phen)CuLCl2]>[(Phen)CoLCl2]>[(Phen)NiL]Cl2>(L).