Methoxy group containing bidentate Schiff base ligands and their transition metal complexes: Synthesis, structural characterisation, photoluminescence, antioxidant capacity and superoxide dismutase activity studies

Exploring the antimalarial and antioxidant efficacy of transition metal(II) chelates of thiosemicarbazone ligands: spectral investigations, molecular docking, DFT, MESP and ADMET

Malaria, a relentless and ancient adversary, continues to cast its shadow over vast swathes of the globe, afflicting millions of people and have a heavy toll on human health and well-being. Despite substantial progress in the fight against this parasitic disease in recent decades, malaria still persists as a substantial global health concern, especially in some specific region which have limited resources and vulnerable populations. Thus, to ascertain an combating agent for malaria and its associated dysfunction, 4-(4-ethylphenyl)-3-thiosemicarbazide and benzaldehydes based two new thiosemicarbazone ligands (1-2) and their cobalt(II), nickel(II), copper(II), zinc(II) metal complexes (3-10) were synthesized in the present research work. The synthesized compounds were comprehensive characterized through spectral and physical investigations, demonstrating octahedral stereochemistry of the complexes. Further, the antimalarial and antioxidant potential of the compounds (1-10) were analyzed by micro assay and DPPH assay protocols, respectively, to examine the therapeutic aspect of the compounds. The performed biological evaluations revealed that the complexes are more efficient in controlling infectious ailment in comparison of ligands. The complexes (5), (6), (10) shows significant efficiency for malarial and oxidant dysfunctions whereas Zn(II) complex (6) exhibit highest potency with 1.02 ± 0.07 and 2.28 ± 0.05 µM IC50 value. Furthermore, to support the highest antimalarial potency of the (3-6) complexes and their associated ligand (1), the computational studies like molecular docking, DFT, MESP and ADMET analysis were executed which were supported the biological efficacy of the complex (6) by providing numerous parameters like binding interaction electronegativity, electrophilicity, HOMO value and electron density.

Synthesis, characterization, antioxidant and anticancer activities of a new Schiff base and its M(II) complexes derived from 5-fluorouracil

In this study, Schiff base ligand was obtained from the condensation reaction of benzene-1,2-diamine and 5-fluoropyrimidine-2,4(1H,3H)-dione (5-FU). Metal(II) complexes were synthesized with Fe(II), Co(II) and Ni(II) chloride salts. The synthesized ligand and metal complexes were characterized by FT-IR, UV-vis, ¹H-¹³C NMR, elemental analyses, mass spectroscopy, magnetic moments, molar conductivity and thermogravimetric analysis studies. With the help of different techniques reveal Fe(II), Co(II) and Ni(II) complexes have exhibited tetrahedral and octahedral geometry. Ligand acted as bidentate and it binds metal(II) ions through deprotonated-NH, imine-N atom and carbonyl-O atom, respectively. DPPH, ABTS, FRAP, CUPRAC and total antioxidant activity methods were used to determine the antioxidant properties of ligand and metal complexes. According to the results, the synthesized compounds showed very high antioxidant activity compared to 5-FU. The cytotoxicities of the synthesized compounds were performed on MCF-7 (human breast cancer) and L-929 (fibroblast) cell lines using the MTT assay. In addition, the effect of electroporation (EP) on the cytotoxicity of the compounds was investigated. Our results demonstrated that novel Co(II) and Ni(II) complexes show potential as new anticancer agents and ECT may be a viable treatment option for breast cancer.

The effect of structural configuration on the DNA binding and in vitro antioxidant properties of new copper(ii) N2O2 Schiff base complexes

DNA interaction with cis and trans-copper NO complexes favours the cis configuration due to low energies observed in the cis configuration.

In Vitro Antioxidant Activities and the Therapeutic Potential of Some Newly Synthesized Chalcones Against 4-Acetaminophenol Induced Hepatotoxicity in Rats

The lack of safety and efficacy of existing hepatoprotective agents urge the need to explore novel hepatoprotective agents. The research work was planned to study the therapeutic potential of some newly synthesized chalcones against 4-acetaminophenol induced hepatotoxicity in rats. Male albino rats (N = 30) were divided into 6 groups of 5 animals each i.e. group I; Toxic control (4-acetaminophenol), group II; normal control (Normal saline), group III; Positive control (silymarin; 50 mg/kg bw) and groups IV-VI (test groups) treated with 3 chalcone analogues i-e 3a, 3f & 3 g (100, 150, 150 mg/kg bw, respectively). All the study group animals were administered with 4-acetaminophenol to induce hepatotoxicity except normal control. Following hepatotoxicity induction, test group animals were administered with selected doses of test compounds and toxic group animals left untreated. Liver enzymes including ALT, AST, ALP and serum bilirubin were determined photometrically. Antioxidant activities of test compounds were also determined. Histopathological examination of liver biopsies was also carried out through H & E staining. The test chalcones (3a, 3f & 3 g) significantly decreased the levels of liver enzymes and serum bilirubin toward normal and the pattern of results in the test group animals were comparable to silymarin administered animals indicating the hepatoprotective potential of test compounds. Moreover, the test chalcones (3a, 3f & 3 g) antagonized the effect of 4-acetaminophenol and thus, raised the catalase (CAT) and superoxide dismutase (SOD) while decreased the malondialdehyde (MDA) in experimental animals. The test chalcones (3a, 3f & 3 g) on histological examination of liver showed improvement of tissue morphology. The study concluded that the tested compounds have antioxidant potential and may act as hepatoprotective agent. However, in-depth studies are required to validate their safety and to elucidate the exact mechanism of action.

Oxovanadium(IV) and Nickel(II) complexes obtained from 2,2'-dihydroxybenzophenone-S-methyl-thiosemicarbazone: Synthesis, characterization, electrochemistry, and antioxidant capability

2,2'-Dihydroxybenzophenone-S-methyl-thiosemicarbazone and 3-methoxy-salicylaldehyde were reacted in the presence of oxovanadium(IV) or nickel(II) ions to yield the N2O2-type-chelate complex. The synthesized complexes were characterized by employing elemental analysis, electronic and infrared spectra, 1H NMR spectra, magnetic measurements, and thermogravimetric analyses. The expected structures of oxovanadium(IV) and nickel(II) complexes were confirmed by using the single-crystal X-ray diffraction method. The presence of π-π stacked dimeric structures provided stronger crystalline formations. The optimized geometries and vibrational frequencies of the compounds were obtained using the DFT/ωB97XD method with the 6-31G (d,p) basis set and compared with the experimental data. The electrochemical characterization of the oxovanadium(IV) and nickel(II) complexes were carried out by using the cyclic voltammetry (CV) method. The oxovanadium(IV) complex gives a ligand-centered oxidation and a metal-centered one electron reduction and oxidation peaks corresponding to the VIV/IIIO and VIV/VO, respectively. The nickel(II) complex gives a ligand-centered oxidation and metal-centered (NiII/I) reduction peaks in a dimethyl sulfoxide (DMSO) solution. The redox potentials were calculated in terms of Gibbs free energy change of the redox reaction at the theory level of M06-L/LANL2DZ/PCM. In addition, the energy gap, HOMO and LUMO distributions were calculated. The total antioxidant capacities of the compounds were determined by using cupric reducing antioxidant capacity (CUPRAC) method, in which the oxovanadium(IV) complex was found to be powerful as an antioxidant agent.

Synthesis of imine bond containing insoluble polymeric ligand and its transition metal complexes, structural characterization and catalytic activity on esterification reaction

In this study, synthesis of insoluble polymeric ligand (L) and its transition metal complexes [Cu(L)Cl₂]·2H₂O (1), [Co(L)Cl₂(H₂O)₂] (2) and [Ni(L)Cl₂(H₂O)₂] (3), having the azomethine groups, were synthesized by the condensation reactions of the diamines and dialdehydes. The structural properties were characterized by the analytical and spectroscopic methods using by elemental analysis, Fourier Transform Infrared, Thermo Gravimetric Analysis, Powder X-ray Diffraction, magnetic susceptibility and Inductively Coupled Plasma. The solubilities of the synthesized polymeric materials were also investigated and found as insoluble some organic and inorganic solvents. Additionally, their catalytic performance was carried out for the esterification reaction of acetic acid and butyl acetate. The highest conversion rate is 75.75% by using catalyst 1. The esterification of butanol gave butyl acetate with 100% selectivity.

Theoretical study on the optical response behavior to hydrogen chloride gas of a series of Schiff-base-based star-shaped structures

Schiff-base compounds have many applications in the field of optoelectronic materials and chemical sensing because of their appealing coordination ability, and simple and easily accessible use in structural modification. Herein, five kinds of star-shaped Schiff-base compounds were designed and their optical response behavior to hydrogen chloride (HCl) gas was studied using dependent/time-dependent density functional theory (DFT/TDDFT). Moreover, the relationship between structures and properties was investigated upon changing the benzene group into N atom or triazine group at the core-position and introducing a methoxyl (-OCH₃) or nitro (-NO₂) group into the star-shaped Schiff-bases at the tail of the branches. The results show that all five Schiff-bases could be candidates for HCl gas sensing materials. Furthermore, introducing an electron-donating group at either the core or the tail forms a charge transfer channel with the electron deficient H-bonded imino group, which is convenient for charge transfer and subsequently promotes a red-shift in absorption spectra and fluorescence quenching.