Monobasic Bidentate Ligand Research Articles

Development of cancer-targeted nano gold functionalized ruthenium(III)-doxorubicin complex: Synthesis, characterization and evaluation of DNA cleavage, anticancer and bioimaging activity

Metal-based drugs have attracted greater attention for cancer diseases because of biological relevance. However, some drawbacks are present in the metal complexes such as low stability and low bioavailability. Nanomaterials functionalized metal complexes can protect the stability and enhanced the bioavailability. In the present study, Nano gold functionalized ruthenium(III) complex from doxorubicin have been synthesized from ruthenium(III) complex and characterized using various spectrochemical techniques such as IR, UV, and NMR. In the metal complex, Doxorubicin (DOX) acts as a monobasic bidentate ligand and is coordinated through the carbonyl oxygen and phenolate oxygen of the anthracene ring. Based on spectral evidences, the complex [Ru(DOX)(PPh3)2Cl2] has an octahedral geometry. The Nano Au-Ru(III) DOX is analysed for their size, and morphology using XRD, SEM and HRTEM. X-ray diffraction pattern revealed that the complex has nanocrystalline in nature. The Nano Au-Ru(III) DOX is spherical shape and particle size is less than 15 nm. The DNA cleavage activity of [Ru(DOX)(PPh3)2Cl2] and Nano Au-Ru(III) DOX has been evaluated using pUC18 plasmid DNA and the results showed significant cleavage. The [Ru(DOX)(PPh3)2Cl2] and Nano Au-Ru(III) DOX have been tested against human breast cancer (MCF-7) and leukemia cancer cell lines (K-562) in vitro for its antitumor effects. The tumour activity of the Nano Au-Ru(III) DOX showed more promising activity than the [Ru(DOX)(PPh3)2Cl2]. The cell imaging of the Nano Au-Ru(III) DOX was examined against epithelial human breast cancer cell line (MDA-MB-231) using fluorescent microscopy. The fluorescence images showed high scattering light in tumour tissue at 100 µg/mL Hence, Nano Au-Ru(III) DOX can serve as a promising drug for cancer therapy and cellular imaging.

New iron(III), cobalt(II), nickel(II), copper(II), zinc(II) mixed-ligand complexes: Synthesis, structural, DFT, molecular docking and antimicrobial analysis

The present framework has as its goal the design and synthesis and characterization of new mononuclear 1:1:1 (M:L:Q) mixed-ligand complexes, including FeLQ, CoLQ, NiLQ, CuLQ, and ZnLQ. The "L," is the 4-[(4-oxo-4,5-dihydro-1,3-thiazol-2-yl)hydrazono]methylphenyl 4-methylbenzenesulfonate, while the "Q," is the 8-hydroxy quinoline. According to the findings, L and Q ligands each play the role of a neutral bi-dentate NN and a monobasic bi-dentate ON ligand, respectively. The findings demonstrated an octahedral shape. The density functional theory (DFT) technique was employed, and the quantum chemical descriptors were assessed, to optimize the molecular structure of the compounds. An in vitro investigation was carried out to investigate the antibacterial and antifungal activities of the compounds. According to the findings, the activity of metal complexes as potential candidates for use as antibiotics and antifungals is much greater than that of their free ligands. The in-silico inhibition of the 1fj4 protein was investigated using molecular docking. ZnLQ complex was the one that inhibited the 1fj4 protein with the greatest degree of success. The fact that this is the case lends credence to the notion that these compounds have the potential to function as launchpads for the development of new classes of antibiotics.
 KEY WORDS: Metal complexes, Schiff-base, Antimicrobial, DFT, Molecular docking
 Bull. Chem. Soc. Ethiop. 2024, 38(1), 147-166. DOI: https://dx.doi.org/10.4314/bcse.v38i1.12

Synthesis, characterization, DFT, biological activity evaluation, and molecular docking analysis of new 8-[(2-hydroxynaphthalen-1-yl)diazenyl]naphthalene-1,3-disulfonic acid based complexes

Three novel metal complexes of 2‑hydroxy-1-naphthaldehyde azine (HNANSA) with iron(III), nickel(II), and copper(II) have been synthesized and characterized. Various analytical methods, such as elemental analysis, infrared spectroscopy, mass spectrometry, ultraviolet–visible spectroscopy, conductivity, magnetic testing, and thermal analysis, have been used to determine the structural and physical properties of the HNANSA and its metal complexes. The results indicated that; the HNANSA acts as a monobasic bi-dentate NO donor ligand and that the metal complexes contain water molecules in different patterns. Also, density functional theory (DFT) calculations have been performed to confirm the molecular structures and to study the quantum chemical parameters of the HNANSA and its metal complexes. Furthermore, the antibacterial, antifungal, anti-inflammatory, and antioxidant activities of the HNANSA and its metal complexes have been in vitro evaluated. The findings revealed that; the metal complexes have higher bioactivty than the free HNANSA ligand. Furthermore, molecular docking analyses have been performed against 2VF5 (Escherichia coli), 3CKU (Aspergillus flavus), 5IKT (Human Cyclooxygenase-2), and 5IJT (human peroxiredoxin 2), to estimate the binding affinities and interactions of the HNANSA and its metal complexes with target proteins. The results suggest that the HNANSA and its metal complexes may have potential applications in the development of new therapeutic agents.

New copper (II) complexes derived from azo pyridone dyes: Structure characterization, thermal properties, and molecular docking studies

Two azo dye ligands, bearing different substituents (chlorine atom or methoxy group) in the para‐position of the phenyl ring, were employed for the synthesis of two Cu(II) chelates. Full structural affirmation of complexes was assessed. X‐ray diffraction measurements revealed that the coordination geometry for Cu atoms in both complexes is square‐pyramidal with a ligand:metal ratio of 2:1 where dyes behave as monobasic bidentate ligands. Thermogravimetric analyses of the complexes and their starting dyes were performed to study their thermal stabilities and decomposition behavior confirming the thermal stability of both dyes and complexes. Antioxidative activity of the complexes has been assigned and compared with their parent ligands revealing that the presence of the electron–donor, methoxy group, in the phenyl ring, in both dye and complex, is responsible for the activity (IC50 values of 1.54 for the dye and 1.30 mM for the complex). It should be stated that the complexation of the methoxy‐substituted dye leads to enhanced antioxidative activity concurrent to a standard antioxidant molecule of ascorbic acid, making this molecule a promising antioxidant agent. Docking study with vascular endothelial growth factor receptor 2 and Aurora kinase A proteins indicate that complexes exhibit higher binding affinities to proteins than the starting ligand dyes. The most promising structure exhibiting the best docking potential toward both proteins is the complex‐bearing methoxy group. The presented results represent a promising start for further investigations of these compounds as potential therapeutic candidates for the treatment of various types of cancer.

Synthesis, spectral and thermal studies of new Schiff base copper(II) complexes with their biological effect on Entomopathogenic nematodes

AbstractNew Schiff base ligands; (Z)‐1,5‐diphenyl‐2‐((thiophen‐2‐ylmethylene)amino)‐1H‐pyrrole‐3‐carbonitrile (L1); or (Z)‐2‐((2,4‐dihydroxybenzylidene)amino)‐1,5‐diphenyl‐1H‐pyrrole‐3‐carbonitrile (H2L2) and their Cu(II) complexes have been isolated and characterized using elemental analysis, spectral (FT‐IR, 1H NMR, UV/vis, EPR), molar conductivity and magnetic moment measurements, in addition to thermal techniques. FT‐IR spectra established that the Schiff base L1 coordinates as neutral bidentate or tridentate ligand. While the Schiff base H2L2 ligates as neutral or monobasic bidentate ligand. The EPR spectra indicated covalent nature of complexes [CuL1(OH)]Cl.2H2O (1), [CuL1(OH)(H2O)2]NO3.2H2O (2), [Cu(H2L2)Cl(H2O)3]Cl.H2O (5) and [Cu(HL2)NO3(H2O)3].H2O (6). The biological effect of Cu(II) ions, current ligands and complexes (1, 5) on the mortality and rate of reproduction of Entomopathogenic nematodes (Heterorhabditis bacteriophora and Steinernema carpocapsae) was studied. The results showed that, the obtained Schiff base ligands and their Cu(II) complexes make detoxification of the lethal effect of Cu(II) ions on the beneficial Entomopathogenic nematodes and complex (1) scored the highest reproduction potential.

Synthesis, characterization, theoretical calculation, DNA binding, molecular docking, anticovid-19 and anticancer chelation studies of some transition metal complexes

The globe has recently been consumed by frightening viral pneumonia (COVID-19). The new strain of the virus, called SARS-CoV-2, belongs to the family of coronaviruses, so research is aimed at screening ligands and drugs for multimodal structure-based structure-design and then docking to the main viral protease to examine the active binding sites. The complexes of Cu(II), Ni(II) Zn(II) and Mn(II) with 3-Cyano-6-(p-chlorophenyl) azo-7-hydroxy coumarin (HL) were synthesized and characterized by elemental analyses, IR, UV-Visible, magnetic measurements and thermal analyses. The measurements of molar conductance showed that all the complexes are non-electrolyte. The IR spectra showed that the ligand (HL) acts as a monobasic bidentate ligand by coordinating via the nitrogen atom (-N = N-) and deprotonated -OH group. Analytical data showed that all complexes exhibited a ratio of 1:1 (metal-ligand). The thermal data indicate that some complexes have outside water molecule and some have within the domain of coordination water molecule, and the complexes display identical fragments of thermogravimetric decomposition that are compatible with the proposed structures. Mass spectra were also used to make the large fragments of the ligand and Ni (II) complex, with the main peaks corresponding to molecular weight using quantum chemical equations.

Synthesis, characterization, DNA binding, and biological action of dimedone arylhydrazone chelates

AbstractA chain of metal(II) chelates that M = Co2+, Ni2+, and Cu2+have been produced from 2‐(4‐sulfadiazine)hydrazono dimedone (HL) and characterized on analyses of elemental, Fourier‐transform infrared (FTIR) spectra, electronic, susceptibility to magnetic fields, and molar conductance. The chelates are nonelectrolytes, according to measurements of conductance. Spectroscopy methods and additional analytical measurements detect pseudo octahedral shape of Co2+and Ni2+chelates, but square planar structure for Cu2+chelate. The ligand (HL) acts as a monobasic bidentate ligand by coordinating via oxygen atom of the carbonyl (C═O) group and the nitrogen atom of the hydrazone moiety (NH) with deprotonation. The enhanced, bond angles, bond lengths, and quantum chemical factors were used to determine the ligand and its complexes. Absorption spectra method and measurements of viscosity were used to investigate DNA linking activity. In the viability experiment of vinblastine and colchicine, the findings of synthesized compounds against the human cancer cell lines MCF‐7 and HepG‐2 were reported in contrast to positive controls. The antioxidant function of chelates is resolute by means of the free radical‐scavenging analyze (DPPH). As a final point, the antimicrobial effects of the chelates were studied utilizing the diffusion disc technique on fungal (Candida albicans), gram‐positive (Staphylococcus aureus), and gram‐negative (Escherichia coli) bacteria.

Effect of N-benzyl group in indole scaffold of thiosemicarbazones on the biological activity of their Pd(II) complexes: DFT, biomolecular interactions, in silico docking, ADME and cytotoxicity studies

A series of N-benzyl substituted indole-based thiosemicarbazone (TSC) ligands (L4-L6) and palladium(II) TSC complexes, [Pd(L)2] (1–6) (L = monoanionic bidentate un/N-substituted indole-based TSC ligand) have been synthesized and characterized using analytical and spectroscopic tools. The exact molecular structures of L4-L6 and the complexes (2–4 and 6) were ascertained by single-crystal X-ray diffraction (XRD) method. Spectroscopic and crystallographic studies indicated that Pd(II) ion was coordinated with TSCs as monobasic bidentate ligands, forming two five-membered rings with square planar geometry. The effect of N-benzyl substitution in indole scaffold of TSCs in the complexes was studied using DFT method, and structure–activity relationships (SAR) were explored. The in silico ADME properties of the ligands and their complexes were thoroughly analyzed with respect to their lipophilicity and oral bioavailability. The complexes (1–6) exhibited strong intercalation with calf thymus DNA (CT DNA), which was examined by absorption/emission spectroscopic titrations and viscosity measurements. Similarly, the interaction of bovine serum albumin (BSA) with complexes examined using spectroscopic methods showed a strong binding between them. A better picture of various possible interactions was acquired from the molecular docking of the complexes with the targets like DNA, BSA, DNA Topoisomerase II and CASP3. In addition, in vitro cytotoxicity of the complexes was screened against two cancer (HeLa-S3 and A549) and one normal (IMR-90) cell lines. It was learnt that the N-benzyl substitution in the indole system inactivated the whole molecule by diminishing its anticancer activity. The unsubstituted indole TSC complex (2) displayed significant activity towards HeLa-S3 cells, and the results were compared with those of cisplatin. Beneficially, the active complex showed less toxicity against IMR-90 normal cells. Further, the results of AO-EB staining studies indicated that the complexes induced cell death via apoptosis pathway. The steric influence of the substituted indole moiety, its limited electronic effects and lesser stability in aqueous systems retarded the Pd(II) complexes of N-benzyl substituted indole TSCs from exhibiting their biological activities.

Synthesis, spectral characterization, DNA binding, catalytic and in vitro cytotoxicity of some metal complexes

A series of 2-(4-sulfamethazine)hydrazono-5,5-dimethylcyclohexane-1,3-dione (HL) and its complexes of Co(II), Ni(II) and Cu(II) (1–3) were synthesized. Elemental measurements, FTIR, 1H NMR, 13C NMR, UV–Visible, X-ray diffraction analysis, and magnetic measurements have characterized the ligand and its complexes. By coordinating with the oxygen atom of the carbonyl group (C=O) and through the hydrazone moiety nitrogen atom (-NH-) with deprotonation, the ligand (HL) functions as a monobasic bidentate ligand. The coordination geometry of the complexes Co(II) and Ni(II) is octahedral, where the complex Cu(II) is square planar. The ligand and its complexes were determined with the optimized bond lengths, bond angles and quantum chemical parameters. The ligand and its complexes calves thymus DNA linking activity was examined through absorption spectra and viscosity measurements. Results of the evaluation of synthesized compounds against the Sections of MCF-7 and HepG-2 active tumor cells have been published in the viability assay for vinblastine and colchicine, relative to positive controls. The DPPH free radical-scavenging assay specifies the in vitro anti-oxidant function of all complexes. Finally, fungal (Candida albicans), gram-negative (Escherichia coli) and gram-positive (Staphylococcus aureus) bacteria have been investigated for the anti-microbial activities of the complexes using the disc diffusion process. Molecular docking was used to predict the binding of SARS-CoV-2 key protease in complex COVID-19 (5REA) between the ligand and breast cancer mutant (3hb5) receptor and the crystal structure.

Structural elucidation, spectroscopic, and metallochromic studies of 2-(2-hydroxy phenyl)-1-H–benzimidazole complexes: Metal ions sensing, DNA binding, and antimicrobial activity evaluation

Three novel chelates, [Ru(L)3]2H2O, C1, [NiL(H2O)3(AcO)]H2O, C2, and [CuL(H2O)(AcO)], C3, derived from 2-(2-hydroxy phenyl)-1-H –benzimidazole) HL, have been designed. The structures of the isolated compounds have been elucidated by elemental analysis, molar conductance, thermal analysis, spectral data (UV–Vis, mass spectra, IR, fluorescence), thermal analysis (TGA) and magnetic moment measurements. The IR spectral data ascertained that the HL compound acts as a monobasic bidentate ligand via the O and N atoms of the OH and C=N groups of the benzimidazole moiety, respectively. The spectral and magnetic measurements implied octahedral structures for C1 and C2 and square planar geometry for C3. The kinetic and thermodynamic parameters of the thermal decomposition stages have been evaluated. Molecular orbital calculations have been performed. The metallochromic behavior of the investigated free ligand was studied in the presence of Ru(III), Ni(II) and Cu(II) ions. The observed spectral changes indicated the ability of HL to act as potential optical sensor for probing these metal ions. Interaction of the investigated compounds with CT-DNA was studied via electronic absorption and emission spectroscopy, as well as ethidium bromide displacement. The results suggested that all compounds interact through intercalative mode. The binding behavior and binding constants have been evaluated and discussed. The CT-DNA-binding constants confirmed the strong intercalation between the investigated ligand and metal complexes with the CT-DNA, suggesting that the investigated compounds can be used as promising therapeutic drug. Finally, the antimicrobial activities of the metal complexes have been screened.

Preparation and Characterization of New Ligand Azo-Schiff-2- Naphthol and Mixed Complexes With Ortho- Aminophenol and Ortho-Aminobenzoic Acid.

The work covered the synthesis and characterization many complexes of mixed ligands with some ions such as Co(II), Ni (II), Cu(II) and Zn(II) metals with new homocyclic azo - azomethine ligand 1-((E)-(4-((Z)-1-(p-tolylimino) ethyl) phenyl) diazenyl) naphthalen-2-ol(TEPDN) and ligand (HL2 =4-Aminoacetophenone ) at (1:1:1) ratio of (M: L1: L2) the complexes was characterized by using elemental analysis Uv-Vis and infrared spectra also their prepared complexes war measured by using the same methods in addition of molar conductance measurements, magnetic susceptibility and determined of metal percent in complexes. The physic- chemical studies and spectra data indicate that ( TEPDN ) ligand and another ligand acts as monobasic bidentate ligand after deprotonated of hydroxyl group

Synthesis of 2‐aminobenzophenone‐based Schiff base Pd(II) complexes: Investigation on crystal structure, biological behavior of DNA/protein‐binding, molecular docking, and in vitro anticancer activities

Two new monobasic bidentate ligands and their Pd(II) complexes have been synthesized and characterized by analytical and spectroscopic methods. The structures of the complexes were confirmed by single‐crystal X‐ray diffraction. The bimolecular binding of the ligands and complexes has been carried out and described. Interestingly, both the bidentate chelating ligands replaced all the triphenyl arsine and chloride ions from the metal precursor in the formation of new complexes and were found to be approximately square planar. The interaction of the ligands and the complexes with calf thymus DNA and bovine serum albumin was studied by electronic and emission spectroscopy techniques, which suggested an intercalation mode of binding. It is well‐known that the viscosity of a DNA solution increases if any compound added binds to it through intercalation because this process lengthens the DNA helix due to the increased separation of the DNA base pairs when the compound slides in between, whereas a partial, nonclassical intercalation could bend (or kink) the DNA helix, which leads to a reduction in length and thereby reducing its viscosity. By contrast, there will be no change in the viscosity when the compounds bind with DNA grooves or by partial intercalation, which was further confirmed by viscosity measurements and molecular docking studies. It has been found that the compounds cleaved supercoiled DNA into nicked DNA without any external agent. The in vitro cytotoxicity studies of the ligands and complexes against human lung (A549) and breast (MCF7) cancer cell lines showed significant activity for both species.

Design, synthesis, spectral characterization, DNA binding, photo cleavage and antibacterial studies of transition metal complexes of benzothiazole Schiff base

Abstract In the present work, a series of Benzothiazole based Schiff base ligand 2-((E)-(6-ethoxybenzo[d]thiazol-2-ylimino)methyl)-4-nitrophenol and their Cu(II), Co(II), Ni(II), Zn(II) and Cd(II) complexes were synthesized and characterized by physical, analytical and spectral data such as elemental analysis, FT-IR, 1H NMR, 13C NMR, ESI-Mass, UVvis, powder XRD, SEM and EDX studies. Based on spectro-analytical experimental data a square planar geometry is confirmed for all these metal complexes. The synthesized Schiff base acts as monobasic bi-dentate ligand which coordinates through imine nitrogen and phenolic oxygen atom to the metal. The metal complexes studies here include interaction of DNA binding studies with CT (Calf thymus) DNA through an intercalative mode. The DNA binding properties of metal complexes have been investigated by using UV–vis electron absorption spectroscopy, fluorescence emission spectra and viscosity measurement techniques. DNA photo cleavage ability evaluated by agarose gel electrophoresis method their transition metal complexes. Moreover, the antibacterial studies five bacterial species was evaluated for metal complexes. Cytotoxicity studies of Schiff base ligand and their metal complexes have been also investigated.

Synthesis and characterization studies of 3‐formyl chromone Schiff base complexes and their application as antitumor, antioxidant and antimicrobial

A novel Schiff base namely (E)‐3‐((2,6‐dihydroxypyrimidin‐4‐ylimino)methyl)‐4H‐chromen‐4‐one and its Co (II), N (II)i, Cu (II) and Cd (II) complexes have been synthesized and proved by elemental analysis, molar conductance, thermal analysis (TGA), Inductive Coupled plasma (ICP), magnetic moment measurements, X‐ray powder diffraction, IR, EI‐mass,1H NMR, 13C NMR,UV–Vis. and ESR spectral studies. On the basis of these data, it is evident that the Schiff base acts as bidentate via oxygen atom of carbonyl group and azomethine nitrogen atom for Co (II) complex; monobasic bidentate ligand for Ni (II), Cu (II) and Cd (II) complexes via oxygen atom of hydroxyl group and nitrogen atom of pyrimidine ring. The results showed all complexes have octahedral geometry. The average particle size of the ligand and its complexes were found to be 1.010–0.343 nm. The pharmacological action (antioxidant, antimicrobial and anticancer) of the prepared compounds is studied. The antitumor activity of the ligand and its metal complexes is evaluated against human liver carcinoma (HEPG2) cell. The data displayed the Co (II) complexes strong cytotoxicity where IC50 values of Co (II) complex and 5‐fluorouracil (stander drug) are 9.33 and 7.86 μg/ml respectively. The Co (II) and Cd (II) complexes have antibacterial activity more than ampicillin (stander drug). The interaction of the synthesized compounds with calf‐thymus DNA (CT‐DNA) has been performed via absorption spectra and viscosity technique. The DNA‐ binding constants have been determined.

Transition metal complexes of a multidentate Schiff base ligand containing guanidine moiety: Synthesis, characterization, anti-cancer effect, and anti-microbial activity

Abstract Guanidine Schiff bases are famous for their distinctive features and medicinal benefits with potential applications for the control of bacterial infections and cancer development. The current study was performed with a prospect to the dinuclear series of Cu(II), Ni(II), Co(II), Mn(II), Fe(III), Cr(III), Bi(III), and Zn(II) complexes of new guanidine Schiff base ligand. These complexes have been arranged and examined by 1H NMR, mass spectra, IR, UV–Vis, ESR spectra, magnetic moments, and conductance measurements, as well as, elemental and thermal analyses (DTA and TGA). The cytotoxicity, the anti-cancer effect, and the anti-microbial activity of these complexes were assessed. The IR spectral data showed that the Schiff base behaved as a neutral bidentate or monobasic bidentate ligand bonded to the metal particles through the azomethine nitrogen atom and the hydroxyl oxygen atom in protonated or deprotonated form embracing tetragonally distorted octahedral geometries. The new complexes were non-hygroscopic dissolvable in DMSO but insoluble in common natural solvents. A molar conductance, in DMF arrangement, demonstrated that the complexes were non-electrolytes. There was a variation in the cytotoxic activity of the complexes on murine spleen cells. Also, cytotoxic and apoptotic effects, indicative of the anti-cancer activity, of the twelve complexes, were noticed against the human hepatoma (HepG2) cell line. Additionally, the newly synthesized complexes showed enhanced anti-tumor and anti-microbial effects in comparison to the parent ligand and to the standard drug.

Synthesis and Evaluation of Cr (III), Mn (III) and Fe (III) Schiff Base of Metals Complexes

A novel synthesized Schiff base metal complexes Cr (III), Mn (III) and Fe (III) of 2-hydroxy-5-chloro acetophenone 2-imino-4-phenyl thiazole were prepared by condensed from 2-hydroxy-5-chloro acetophenone and 2-amino-4-phenyl thiazole have been synthesized and characterized on the basis of elemental analysis, Infrared, 1H NMR, molar conductance and magnetic susceptibilities analysis. The Schiff base acts as a monobasic bidentate ligand commonly coordinates through the oxygen atom of phenolic OH group and the nitrogen atom of azomethine group, which is confirmed by IR spectral data. All the metal complexes have studies thermal properties and their thermal parameter.
 Keyword: Schiff base, Magnetic, Thermal studies.

Synthesis, characterization and biological properties of oxovanadium(IV) complexes

The complexes of oxovanadium(IV) with bidentate heterocyclic azo pyrazolone were synthesized and characterized by elemental analyses, IR, UV–Visible, EPR and magnetic measurements as well as thermal analysis and X-ray diffraction. Reaction of [VIVO(acac)2] (where acac = acetylacetonate) in methanol with azo pyrazolones (HLn) produced mononuclear vanadium(IV) oxo complexes with general formula [VO(Ln)2]H2O. The molar conductance measurements proved that all the complexes are non-electrolytes. IR spectra showed that the ligands (HLn) acts as a monobasic bidentate ligand by coordinating via the nitrogen atom of the pyrazole ring (HNN = ) and deprotonated hydroxyl O, thereby forming a square pyramidal chelating ring. Analytical data revealed that all the complexes exhibited 1:2 (metal-ligand) ratio. The thermal data confirm that the complexes have water molecule outside the coordination sphere and the complexes show similar thermogravimetric decomposition fragments which are consistent with the proposed structures. The thermodynamic parameters of VO(II) complexes are calculated using Coats–Redfern and Horowitz-Metzger methods. The optimized bond lengths, bond angles and the calculated quantum chemical parameters for VO(II) complexes (1–3) were investigated. Their interactions with calf thymus DNA were investigated by absorption spectra and viscosity measurements. The results suggest that these complexes bind to DNA in an intercalative mode (Kb = 4.58–8.96 × 105 M−1). All VO(II) complexes (1–3) were evaluated against human cancer cell lines, MCF-7 and HepG-2 as compared with the positive controls in the viability assay of colchicine and vinblastine. Complex 2 (IC50 = 30.5 ± 2.3 and 20.1 ± 1.9 μg/ml) exhibit moderate activities against the two cell lines MCF-7 and HepG-2, respectively as compared to the Colchicine (IC50 = 17.7 ± 0.03 and 10.6 ± 0.01 μg/mL). The antimicrobial activities of VO(II) complexes were tested against gram negative bacteria (Escherichia coli), gram positive bacteria (Staphylococcus aureus) and fungal (Candida albicans).

Synthesis, characterization, DNA binding and antitumor activities of Cu(II) complexes

A series of Cu(II) complexes of 5,5-dimethyl-2-(2-arylhydrazono)cyclohexane-1,3-dione (HLn) were synthesized by the coupling of dimedone with aniline and its derivatives. These ligands and their Cu(II) complexes were characterized by elemental analyses, IR, 1H NMR, 13C NMR, UV–Visible, X-ray diffraction analysis and magnetic measurements. Spectral studies revealed that the ligand exist in an internally hydrogen bonded keto-hydrazone form rather than the azo-enol form. The ligands (HLn) acts as a monobasic bidentate ligand by coordinating via the nitrogen atom of the hydrazone moiety (NH) with deprotonation and oxygen atom of the carbonyl (CO) group. The optimized bond lengths, bond angles and quantum chemical parameters of the complexes were calculated. The calf thymus DNA binding activity of the ligands and their Cu(II) complexes were studied by absorption spectra and viscosity measurements. The antimicrobial activities of ligands and Cu(II) complexes were tested against Gram negative bacteria (Escherichia coli), Gram positive bacteria (Staphylococcus aureus) and fungal (Candida albicans). The cytotoxic activity of ligands and Cu(II) complexes was tested against two human cancer HePG-2 (Hepatocellular carcinoma) and MCF-7 (breast cancer). The antioxidant activities of ligands and Cu(II) complexes were performed by ABTS method.

Syntheses, characterizations, crystal structures, antibacterial and SOD-like activities of nickel(II) and copper(II) complexes with 2-((Z)-(4-methoxyphenylimino)methyl)-4,6-dichlorophenol

Three mononuclear nickel(II) and copper(II) complexes, [Ni(L)2(py)2] (1), [Ni(L)2(DMF)(H2O)] (2), and [Cu(L)2] (3), where HL = 2-((Z)-(4-methoxyphenylimino)methyl)-4,6-dichlorophenol, py = pyridine and DMF = N,N-dimethylformamide, have been synthesized and their structures determined by single crystal X-ray analysis. Complexes 1–3 crystallized in the monoclinic system of the space groups C2/c, P21/n, and P21/c, respectively. The crystal structures of 1 and 2 present an octahedral geometry at the metal center and 3 shows a square-planar geometry. The FT-IR spectra, UV–vis spectra, and magnetic susceptibility measurements agree with the observed crystal structures. EPR spectra indicate a dx2–y2 ground state (g|| > g⊥ > 2.0023 and A|| > A⊥) for 3 at RT and LNT. The results of simultaneous TG-DTA analyses of 1 and 3 showed the final degradation products are NiO for 1 and CuO for 3. The Schiff base (HL) behaves as monobasic bidentate ligand possessing N and O donor atoms. Electrochemical properties for the complexes are similar and involve two irreversible redox processes. Complex 3 exhibits the ability to inhibit jack bean urease, although its Schiff base has no ability to inhibit urease. Complex 1 exhibits more active scavenging effects against O2− than HL, 2 and 3 under the same conditions. Antibacterial screening activities of these complexes were also investigated.

Evaluation of Anti-Hyperglycemic Effect of Synthetic Schiff Base Vanadium(IV) Complexes

A chain of new vanadium(IV) complexes of Schiff bases, derived from acetohydrazide (HL1-3) or 4-aminoantipyrine (HL4-7) have been prepared and physicochemically distinguished using different tools including analytical, spectral, and magnetic techniques. The spectral and analytical data showed that ligands HL1-3 acted as neutral bidentate ligands, chelated through hydrazono carbonyl and azomethine groups, whereas HL4 acted as neutral tetradentate ligand coordinated via pyrazolone carbonyl, NH group, hydrazono carbonyl, and azo (N=N) groups forming binuclear complexes. The HL5 and HL6 behave as neutral bidentate ligands coordinating through pyrazolone carbonyl and NH groups; in case of ligand HL6, in addition to the mentioned mode, C=N and CN groups participated to bind a second VO(II) ion form binuclear complexes. HL7 behaves as a monobasic bidentate ligand bonded via deprotonated OH and azomethine groups. All complexes adopt square pyramidal geometry around vanadium ion. Results revealed that the oral management of vanadium complexes significantly reduced the blood glucose level in rats suffered from diabetes. The correction of altered biochemical parameters via treatment with vanadium complexes points the improved glucose balance.