Complex CuL Research Articles

Anti-Malarial and Multi-Bioactive Co (II), Cu (II) and Ni (II) Salen Complexes: Synthesis, Characterization and Computational Studies.

Herein, we report the anti-malarial, anti-bacterial and anti-inflammatory activities of the N2O2 donor tetradentate salen type ligand and its CoL, NiL, and CuL metal complexes. The synthesized compounds were characterized by various spectroscopic analytical methods. The in-vitro anti-malarial investigations revealed that the complex CuL exhibited equipotency with quinine drug having IC50 value 0.25 μg/mL. The compound L showed significant inhibition of bacterial spp. viz. E. Coli, P. Aeruginosa, and S. Aureus (MIC=12.5-50 μg/mL), while the compound CoL (MIC=12.5 μg/mL) exhibited potency against gram-positive bacteria. In the in-vitro anti-inflammatory study, the compound CuL displayed moderate activity than other tested compounds. The compound CuL showed the highest anti-malarial docking score with enzyme pLDH at -8.12 Kcal/mol. The DFT study also gives authentication of higher antimalarial activity of CuL due to high dipole moment. None of the potent compounds was found cytotoxic towards vero cell lines.

Cytotoxic Cu(II) Complexes with a Novel Quinoline Derivative Ligand: Synthesis, Molecular Docking, and Biological Activity Analysis.

The utilization of metallodrugs as a viable alternative to organic molecules has gained significant attention in modern medicine. We hereby report synthesis of new imine quinoline ligand (IQL)-based Cu(II) complexes and evaluation of their potential biological applications. Syntheses of the ligand and complexes were achieved by condensation of 7-chloro-2-hydroxyquinoline-3-carbaldehyde and 2,2'-thiodianiline, followed by complexation with Cu(II) metal ions. The synthesized ligand and complexes were characterized using UV-vis spectroscopy, TGA/DTA, FTIR spectroscopy, 1H and 13C NMR spectroscopy, and pXRD. The pXRD diffractogram analysis revealed that the synthesized ligand and its complexes were polycrystalline systems, with nanolevel average crystallite sizes of 13.28, 31.47, and 11.57 nm for IQL, CuL, and CuL 2 , respectively. The molar conductivity confirmed the nonelectrolyte nature of the Cu(II) complexes. The biological activity of the synthesized ligand and its Cu(II) complexes was evaluated with in vitro assays, to examine anticancer activity against the MCF-7 human breast cancer cell line and antibacterial activity against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacterial strains. The CuL complex had the highest cytotoxic potency against MCF-7 breast cancer cells, with an IC50 of 43.82 ± 2.351 μg/mL. At 100 μg/mL, CuL induced the largest reduction of cancer cell proliferation by 97%, whereas IQL reduced cell proliferation by 53% and CuL 2 by 28%. The minimum inhibitory concentration for CuL was found to be 12.5 μg/mL against the three tested pathogens. Evaluation of antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl revealed that CuL exhibited the highest antioxidant activity with IC50 of 153.3 ± 1.02 μg/mL. Molecular docking results showed strong binding affinities of CuL to active sites of S. aureus, E. coli, and estrogen receptor alpha, indicating its high biological activity compared to IQL and CuL 2 .

Synthesis, characterization and biological studies of novel copper(II) and Ni(II) complexes and triphenylphosphine

AbstractFour new complexes of transition metals CuL2, Ni2L2(μ‐Cl)2,Cu2(LH) 2P(Ph)3(H2O)(μ‐Cl)2, [Ni(LH)P(Ph)3Cl2(H2O)]H2O, based on the ligand [2‐(benzo[d]thiazol‐2‐yl)phenol] (L) were synthesized and characterized by FTIR, NMR (1H,13C,31P), ESI‐MS and UV–visible spectroscopy. Spectral data show that the CuL2 complex has a distorted square geometry, octahedral for the Cu2(LH)2P(Ph)3(H2O)(μ‐Cl)2 [Ni(LH)P(Ph)3Cl2(H2O)]H2O complexes and tetrahedral for the Ni2L2(μ‐Cl)2 complex. Remarkable antioxidant and antibacterial activity against four strains for the complexes and ligand L was investigated. Cytotoxicity study was made on the germination of Lepidium sativum seeds, and on the behavior of erythrocytes and leukocyte nuclei. All synthesized products showed no hemolytic and genotoxic effects on erythrocytes and leukocyte nuclei, respectively. The results of the present study indicate that the synthesized ligand and its complexes tested are safe to human blood cells, and they might be used as active agents for pre‐clinical trials.

Enhancement of the Cytotoxicity of Quinazolinone Schiff Base Derivatives with Copper Coordination

Two copper(II) complexes (Cu-L1, Cu-L2) derived from 2,3-substituted quinazolinone Schiff base ligands (L1, L2) were prepared to examine their anticancer activity. Compounds were characterized using various spectroscopic methods (FTIR, NMR, UV-vis) and quantum-chemical calculations. The biological effects of Cu(II) complexes bearing quinazolinone scaffolds were evaluated on two cancers’ cell lines (breast—MCF-7 and lung—A549), as well as on untransformed cells (keratinocytes—HaCaT). Copper complexes were highly cytotoxic, with IC50 in the low micromolar range, while the quinazoline ligands L1 and L2 remained inactive in inhibiting cell proliferation. Antioxidant activity was investigated in the model systems using DPPH and FRAP assays. The Cu-L1 and Cu-L2 complexes exhibited enhanced DPPH free radical scavenging efficiency compared to the L1 and L2 ligands, but their reducing ability was comparable to that of the free ligands. Evaluation of oxidative stress in vitro carried out by staining cells with various ROS-specific indicators showed reduced production of superoxide anion radical and hydrogen peroxide after treatment of cells with copper complexes. Such a negative impact on ROS formation in cells can lead to cellular redox imbalance and consequent cell death, among others, by inducing apoptosis and/or necrosis, depending on the copper complex used. We hypothesize that the high cytotoxic activity of the investigated copper complexes is apparently the result of multiple mechanisms of action, and the imbalance in the cellular antioxidant system partly contributes to the overall cytotoxic effect.

Rhodamine hydrazide-linked naphthalimide derivative: Selective naked eye detection of Cu2+, S2− and understanding the therapeutic potential of the copper complex as an anti-cervical cancer agent

A naphthalimide-labeled rhodamine hydrazone derivative HL has been synthesized, characterized and examined in metal ion recognition. It shows selective colorimetric detection of Cu2+ over a number of other metal ions with a detection limit of 1.66 × 10−7 M in CH3CN/HEPES buffer (v/v = 2:1, pH = 6.8). The spirolactam ring of rhodamine and the imino-phenol motif of naphthalimide in HL are involved in complexation of Cu2+ as shown by single crystal X-ray. Single crystal of the copper-complex is prepared by utilizing NaSCN and it is characterized as CuL(SCN). The emergence of new absorption at 550 nm in UV–vis and the pink color of the solution reveal the selective interaction toward Cu2+. HL is characterized as a fluorescence resonance energy transfer (FRET) system that remains ‘turned OFF’ while spirolactam ring exists. In the presence of Cu2+, FRET is ‘turned ON’ via the opening of spirolactam ring to give emission at 580 nm which is less intense due to the quenching effect of Cu2+ ion. The complexation is reversible and the ensemble of Cu2+.HL selectively recognizes S2− over a series of different anions involving a color change from pink to colorless via the formation of spirolactam ring. The copper complex CuL(SCN) is further employed to understand its efficacy as a therapeutic agent. The complex is cytotoxic to high-risk HPV positive cervical cancer cell lines like SiHa and HeLa and is efficient in the generation and accumulation of reactive oxygen species (ROS). The complex also initiates nuclear blebbing and shows DNA degradation as understood by DNA laddering assay.

Effect of Cu+/2+ ions on the biological activity of their bis‐oxalyldihydrazone complexes: ctDNA interaction, antimicrobial and anticancer action

Two bimetallic homoleptic complexes (CuL1 and CuL2) were synthesized from the coordination of Cu+/2+ ions with diisatin oxalyldihydrazone ligand (H2Lx), respectively. Confirmation of their chemical structures was based on the investigation of alternative spectroscopic tools. To distinguish the role of Cu+/2+ ion and its various charges on their complexes' reactivity, the bioreactivity of H2Lx, CuL1, and CuL2 was established on the spectral results against the growth of some microbial series (fungi and bacteria) and against three human cancer/normal cells. Furthermore, their behavior towards calf thymus DNA (ctDNA) was evaluated through viscometric and spectrophotometric titration. Both CuL1 and CuL2 complexes exhibited an amazing inhibiting effect against the growth of the titled microbial series and the human cancer cells, corresponded to the inhibited zone (mm), MIC (μM), and IC50 magnitudes (μM) and compared with those of their uncoordinated H2Lx ligand. CuL1 demonstrated a featured interacted behavior against ctDNA over that of CuL2 depending on the obtained intrinsic binding constants and the derived Gibbs' free energy values. The assigned nature of interaction could be built on the covalent and/or noncovalent modes, which supported by the electronegativity and electrophilicity of the titled studied compounds towards ctDNA.

Biophysical study on DNA and BSA binding activity of Cu(II) complex: Synthesis, molecular docking, cytotoxic activity, and theoretical approach

The bidentate (N, O) donor Schiff base, methyl‐4‐(2‐hydroxybenzylidene‐amino) benzoate (HL), was synthesized for the synthesis of CuL2 complex. Their structures were characterized by single crystal X‐ray diffraction and spectroscopic methods. The important structural features of ligand HL are (space group: Pca21; a = 6.1434(7) Å; b = 7.1021(7) Å; c = 28.963(3) Å; α = 90.00°; β = 90.00°, and γ = 90.00°) and of CuL2 are (space group: P21/n; a = 15.763(7) Å; b = 8.1921(5) Å, and c = 20.1955(8) Å; α = 90.00°; β = 96.547(4)°, and γ = 90.00°). The DFT/TD‐DFT studies were performed to evaluate the structure optimization, MEP plot, and electronic spectroscopy data as well as the HOMO‐LUMO energy and also other electronic descriptor properties. The DNA and BSA binding property of both the ligand and complex were studied employing a variety of spectroscopic methods, viscosity experiments, and gel electrophoresis technique. Their biophysical study including 3D fluorescence, FRET calculation, and anisotropy measurements with BSA were studied by spectrofluorometric methods. The molecular docking simulation of the ligand HL and CuL2 was executed with DNA and BSA to observe their different weak and strong binding interactions and to compare their binding aptitude with biomolecules and experimental results. The software “PASS” for drug likeness prediction and “ADMET” for bioactivity were implemented to get an idea about the antineoplastic and bioactivity aspects of HL and CuL2 complex. The anticancer property of the Cu(II) complex was measured by MTT assay against human breast carcinomas (MCF‐7) cancer cell line and as well as normal human embryonic kidney cells (HEK293) and is less toxic and comparable anticancer activity compared to cisplatin and oxaliplatin. The annexin V‐FITC, propidium iodide assay by flow cytometric method, and reactive oxygen species (ROS) production assay by DCFDA were assessed in presence of the HL and CuL2 for their cell death mechanism proceed via either apoptosis or necrosis.

Physical structure of constitutional isomers influences antiproliferation activity of thiosemicarbazone-alkylthiocarbamate copper complexes

A series of hybrid thiosemicarbazone-alkylthiocarbamate copper complexes with similar electronic environments but distinct physical structures have been prepared, characterized, and evaluated for antiproliferation activity. The complexes include the constitutional isomers (1-phenylpropane-1-imine-(O-ethylthiocarbamato)-2-one-(N-methylthiosemicarbazonato))copper(II) (CuL1) and (1-phenylpropane-1-one-(N-methylthiosemicarbazonato)-2-imine-(O-ethylthiocarbamato))copper(II) (CuL2) along with (1-propane-1-imine-(O-ethylthiocarbamato)-2-one-(N-methylthiosemicarbazonato))copper(II) (CuL3). Complexes CuL1 and CuL2 differ in the positions of the pendent thiosemicarbazone (TSC) and alkylthiocarbamate (ATC) moieties on the 1-phenylpropane backbone. Complex CuL3 employs a propane backbone with the TSC in the 2-position as in CuL1. The isomer pair CuL1 and CuL2 have equivalent electronic environments with indistinguishable CuII/I potentials (E1/2 = -0.86 V vs. ferrocenium/ferrocene) and electron paramagnetic resonance (EPR) spectra (g∥ = 2.26, g⊥ = 2.08). The electronic structure of CuL3 has a similar E1/2 of -0.84 V and identical EPR parameters to CuL1, 2. Single crystal X-ray diffraction studies confirm a consistent donor environment with no substantial variation in the CuN or CuS bond distances and angles between the complexes. The antiproliferation activities of the CuL1–3 were evaluated against the lung adenocarcinoma cell line (A549) and nonmalignant lung fibroblast cell line (IMR-90) using the MTT assay. CuL1 had the highest A549 activity (A549EC50 = 0.065 μM) and selectivity (IMR-90EC50/A549EC50 = 20). The constitutional isomer CuL2 displayed decreased A549 activity (0.18 μM) and selectivity (10.6). The complex CuL3 displayed activity (0.009 μM) similar to CuL1 but with a lack of selectivity (1.0). Cellular copper loading determined by ICP-MS was consistent with the activity and selectivity trends. The complexes CuL1–3 did not induce reactive oxygen species (ROS) generation.

INVESTIGATING THE STRUCTURAL AND SURFACE PROPERTIES OF COPPER AND NICKEL COMPLEXES FLUORINE-BASED SALEN TYPE SCHIFF BASES

Two new transition metal complexes, NiL1 (1) and CuL2 (2), with formulations C18H12F6N2NiO4 and C18H12CuF6N2O4, respectively, were synthesized through the slow evaporation method in ethanol. The synthesized complexes were extensively characterized using X-ray diffraction, Fourier transform infrared spectroscopy, and UV-Vis spectroscopy techniques. X-ray crystallographic analysis revealed that the Ni(II) and Cu(II) salen complexes consist of double deprotonated tetrafunctional chelating ligands, namely L1 for NiL1 and L2 for CuL2, along with the corresponding metal cations, Ni+2 and Cu+2. The asymmetric unit of NiL1 comprises half of the molecule, while the asymmetric unit of CuL2 consists of a single molecule. In the crystal lattice, the molecules of both complexes are interconnected through C–H···O and C–H···F hydrogen bonds. Additionally, weak π···π interactions contribute to the formation of a layered structure in both complexes. To gain further insight into the intermolecular interactions, Hirshfeld surface analysis was employed, enabling the identification of atom locations with potential for hydrogen bonding and providing a quantitative assessment of these interactions in the complexes. The analysis revealed that the dominant contributions to the Hirshfeld surface originated from F···H, H···H, and O···H contacts in both NiL1 and CuL2 complexes.

Synthesis, DFT, Biological and Molecular Docking Analysis of Novel Manganese(II), Iron(III), Cobalt(II), Nickel(II), and Copper(II) Chelate Complexes Ligated by 1-(4-Nitrophenylazo)-2-naphthol

Novelmanganese(II), iron(III), cobalt(II), nickel(II), and copper(II) chelates were synthesized and studied using elemental analysis (EA), infrared spectroscopy, mass spectrometry, ultraviolet-visible spectroscopy, and conductivity, as well as magnetic measurements and thermogravimetric analysis (TG). The azo-ligand 1-[(4-nitrophenyl)diazenyl]-2-naphthol (HL) chelates to the metal ions via the nitrogen and oxygen centers of the azo group and the hydroxyl, respectively. The amounts of H2O present and its precise position were identified by thermal analysis. Density functional theory (DFT) was employed to theoretically elucidate the molecular structures of the ligand and the metal complexes. Furthermore, the quantum chemical parameters were also evaluated. The antimicrobial properties were evaluated against a group of fungal and bacterial microbes. Interestingly, the bioactivity of the complexes is enhanced compared to free ligands. Within this context, the CuL complex manifested the lowest activity, whereas the FeL complex had the greatest. Molecular docking was used to foretell the drugs' binding affinity for the structure of Escherichia coli (PDB ID: 1hnj). Protein-substrate interactions were resolved, and binding energies were accordingly calculated.

Tetracoordinated ONNO donor purine‐based Schiff base and its metal complexes: Synthesis, characterization, DNA binding, theoretical studies, and bioactivities

AbstractTetracoordinated ONNO purine‐based novel Schiff base (1) and its metal complexes Co(II), Ni(II), Cu(II), and Zn(II) (2–5) were procured from 2,6‐diaminopurine and 5‐chlorosalicylaldehyde and characterized by elemental analyses, IR, UV–Vis, magnetic measurements, ESI‐MS, 1H NMR, and 13C NMR analysis. The new complexes showed an interesting structural variation: Distorted tetrahedral (CoL, CuL, and ZnL) and tetrahedral (NiL) geometries indicate that the metal ions bind with ligands through ONNO coordination sites. Density functional theory (DFT) and neutral bond orbital (NBO) calculations were performed to obtain an understanding of the structural characteristics, orbital interactions, and electronic chemical descriptors evaluation. Absorption and fluorescence spectra have been employed to examine the calf thymus deoxyribonucleic acid (CT‐DNA)‐binding behavior of the ligand and its complexes. Pharmacological activities, including in vitro antioxidant, in vitro anti‐inflammatory, and in vitro antidiabetic assays, were performed. All compounds showed better activities compared with the free ligand. For anti‐inflammatory and antidiabetic assays, ZnL complex showed high activity, whereas CuL complex exhibited the highest antioxidant activity among other metal complexes. Moreover, the zone of inhibition (ZOI) and minimum inhibitory concentration (MIC) of the synthesized compounds were screened for in vitro antibacterial activity against Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Here also, complexes exhibited better antibacterial activity than the free ligand, especially the ZnL complex. The docking active site interactions were gauged to predict the activity of ligand and its metal complexes by binding with distinct active sites of B‐DNA dodecamer (for DNA‐binding activity), cyclooxygenase‐2 (for anti‐inflammatory assay), and α‐amylase enzyme and α‐glucosidase enzyme of human pancreatic system (for antidiabetic assay). The results indicated that the compounds are worth further investigation as a possible therapeutic agent.

Synthesis, Characterization, Antibacterial and Antioxidant Studies of Isoniazid-based Schiff Base Ligands and Their Metal Complexes

The condensation of aromatic aldehyde with amine results in the formation of Schiff's bases, which are considered to be one of the most significant groups of ligands. Schiff's base metal complexes have received a lot of attention because of their high biological activity. Such include antimicrobial, anticancer, antibacterial, and antifungal activities. The current research is focused on the synthesis and characterization of two Schiff's base ligands obtained from the reaction of isoniazid with 4-(N,N-dimethylamino)benzaldehyde (L1) and 5-nitro-2-furfurldehyde (L2), respectively and their metal complexes with Cu2+, Zn2+, and Ni2+ ions. FT-IR, UV-Vis, conductivity, and magnetic susceptibility (µeff) measurements were used to describe the ligands (L1 and L2) and their complexes. The square planar geometry of Cu2+ and Ni2+ complexes, as well as the tetrahedral geometry of Zn2+ complexes, are supported by the Uv-Vis spectra and magnetic moments data. Their antibacterial effectiveness against various pathogenic microorganisms was evaluated in the presence of standard Kanamycin-30. The CuL2 complex, among all the metal complexes derived from the L2 ligand, exhibited better antibacterial activity against S. aureus than that of Kanamycin-30. When compared to the BHT antioxidant, all Cu2+ complexes showed excellent efficacy.

Isoniazid Derived Schiff Base Metal Complexes: Synthesis, Characterization, Thermal Stability, Antibacterial and Antioxidant Activity Study

Transition metal complexes of Cu2+, Ni2+ and Co2+ with the Schiff base ligand, N-(2-methoxybenzylidene)isonicotinohydrazone, (L1) were synthesized by the conventional condensation approach. Ligand and its metal were characterized by FT-IR, UV-Vis, Magnetic moment measurements and Thermogravimetric (TGA) analysis. IR spectra revealed that the Schiff base ligand coordinated to the metal ion through nitrogen (N) of azomethine group and oxygen (O) of carbonyl group. IR data coupled with TGA analysis confirmed the presence of coordinated water molecules. Antibacterial activity for both ligand and its complexes were investigated against some pathogenic bacteria and the best activity was observed in the case of the CuL1 against E. coli when compared with standard drug, Kanamycin-30. The antioxidant activity of the CuL1 complex was the greatest among all the complexes when compared to that of BHT.

New mononuclear Fe(III), Co(II), Ni(II), Cu(II), and Zn(II) complexes incorporating 4‐{[(2 hydroxyphenyl)imino]methyl}phenyl‐4‐methylbenzenesulfonate (HL): Synthesis, characterization, theoretical, anti‐inflammatory, and molecular docking investigation

Herein, new Fe(III), Co(II), Ni(II), Cu(II), and Zn(II) complexes incorporating 4‐{[(2‐hydroxyphenyl)imino]methyl}phenyl 4‐methylbenzenesulfonate Schiff‐base ligand (HL) were designed, synthesized, and characterized. The structure of the new compounds was elucidated based on spectroscopic techniques (nuclear magnetic resonance [NMR], ultraviolet–visible [UV‐vis], infrared [IR], mass), magnetic, conductivity, thermal analysis (thermogravimetric analysis [TGA], differential thermal analysis [DTA]) measurements, in addition to complex stoichiometry determination using molar ratio and Job's methods. The new complexes showed an interesting structural variation: square‐planar (in the case of NiL), tetrahedral (in the case of CuL), and octahedral (in the case of FeL2, CoL2, and ZnL2). Furthermore, density functional theory (DFT) calculations were performed to obtain deep insights into the structural features, orbital interactions, and electronic chemical descriptors evaluation. Moreover, the anti‐inflammatory behavior of the titled compounds was in vitro investigated. Interestingly, the ZnL2 complex showed the highest activity, whereas the CuL complex showed the lowest activity compared with the other compounds. In order to ascertain the bioactivity of the present compounds, their efficacy was compared with previously reported compounds showing high activity. The anti‐inflammatory activity was supported by molecular docking analysis against cyclooxygenase‐2 (COX‐2) enzyme (PDB ID: 5IKT), which confirms the bioactivity behavior. The obtained results indicated that the titled compounds could be promising anti‐inflammatory candidates.

Bidimensional Polyiodide Netting Stabilized by a Cu(II) Macrocyclic Complex

Iodine-dense polyiodide phases are interesting materials for a number of potential uses, including batteries and solid-state conductors. The incorporation of transition metal cations is considered a promising way to enhance the stability, tune the properties, and influence the architecture of polyiodides. However, several interesting metals, including Cu(II), may suffer redox processes, which generally make them not compatible with the I2/I− redox couple. Herein L, a simple derivative of cyclen, is proposed as a Cu(II) ligand capable of protecting the +2 oxidation state of the metal even in the presence of polyiodides. With a step by step approach, we report the crystal structure of free L; then we present spectrophotometric verification of Cu(II) complex stability, stoichiometry, and formation kinetic in DMF solution, together with Cu(II) binding mode elucidation via XRD analysis of [Cu(L)Cl]ClO4∙CH3CN crystals; afterwards, the stability of the CuL complex in the presence of I− is demonstrated in DMF solution, where the formation of a Cu:L:I− ternary complex, rather than reduction to Cu(I), is observed; lastly, polyiodide crystals are prepared, affording the [Cu(L)I]2I3I5 crystal structure. This layered structure is highly peculiar due to its chiral arrangement, opening further perspective for the crystal engineering of polyiodide phases.

Antimicrobial, photocatalytic action and molecular docking studies of imidazole-based Schiff base complexes

CoL2, NiL2, CuL2 and ZnL2 mononuclear Schiff base complexes were synthesized by using a condensation process between imidazole-2-carboxaldehyde and 2-aminobutyric acid. Infrared, electronic, elemental, and magnetic investigations were performed on the four coordinated mononuclear Schiff base complexes. The SEM images confirmed the particle size was micrometre range with different morphological appearances of the respective synthesized compounds. UV–vis. spectra were used to explore the photocatalytic activities of ML2 complexes, using methylene blue (MB) as a target dye impurity for degradation. All the complexes show good catalytic activity towards the degradation of MB. Among the catalysts, the CoL2 and CuL2 complexes exhibit maximum percentage degradation of 88 and 87.5 % respectively after 90 min. irradiation of sunlight. Conventional H-bond, hydrophobic, and π-alkyl-interactions are predominant, with excellent binding affinities, according to molecular docking studies of Schiff base with the observed biological receptors. The in vitro antimicrobial studies revealed that all synthesized ML2 complexes exhibit significant activities as compared to the ligand. The complex CuL2 shows maximum antimicrobial action against E. coli, S. aureus, and C. albicans.

Microwave synthesis, Characterisation and Biological activities of transition metal complexes with Novel SNSN Donor Schiff base ligand

A novel Schiff base (E)-N-(pyridine-2-yl)thiophen-2-ylmethylene)hydrazine carbothioamide (L), was synthesised by the condensation of thiophen-2-carbaldehyde and N-(pyridin-2-yl)-hydrazinecarbothiamide, using solvent free microwave synthesis. The Co(II), Ni(II), Cu(II) and Zn(II) complexes of the ligand were also prepared. They were characterised by elemental analysis, EI-mass spectrum, 1H & 13C-NMR spectrum, FTIR, UV-Vis spectra, magnetic, EPR spectra and thermal analysis. The “SNSN” donor ligand binds the metal ion in tetradentate mode through thiophenyl and thioenolic sulphur atoms and imino and pyridine nitrogen atoms. The electronic spectra along with magnetic measurements demonstrate tetrahedral geometry for Co(II), Ni(II) and Zn(II) complexes whereas square planar geometry for CuL complex. All the complexes were found to be thermally stable from thermogravimetric studies. The complexes show enhanced antibacterial activity than the ligand against various bacterial strains. The BSA binding activity of the complexes shows that the affinity for binding was greater towards copper complex. The cytotoxicity of the ligand and its complexes were tested on HT29 colon cancer cells using MTT assay.

Synthesis and Complexation Properties of 2-Hydroxy-5-methoxyphenylphosphonic Acid (H3L1). Crystal Structure of the [Cu(H2L1)2(\u041d2\u041e)2] Complex

2-Hydroxy-5-methoxyphenylphosphonic acid (H3L1) and the complex [Cu(H2L1)2(H2O)2] were synthesized and characterized by IR spectroscopy, thermogravimetry, and X-ray diffraction analysis. The polyhedron of the copper atom is an axially elongated square bipyramid with oxygen atoms of phenolic and of monodeprotonated phosphonic groups at the base and oxygen atoms of water molecules at the vertices. The protonation constants of the H3L1 acid and the stability constants of its Cu2+ complexes in water were determined by potentiometric titration. The protonation constants of the acid in water are significantly influenced by the intramolecular hydrogen bond and the methoxy group. The H3L1 acid forms complexes CuL‒ and CuL24‒ with Cu2+ in water.

DNA-binding and Kinetics AChE Inhibition studies of Cobalt(II) and Copper(II) Complexes Derived from 5-[4-(dimethylamino) phenyl]-3-(2-oxo-2H-chromen-3-yl)-1H-pyrazole-1-carbothioamide

A series of transition metal complexes of the general formula [MLCl(H2O)2] ,M=Co(II) and Cu(II) and L=3-(pyridine-2-yl)-4,5-dihydro-1H-pyrazole-1-thiocarboxamides (L) have been synthesized by a two steps reaction sequence starting from substituted Benz aldehydes and 2-acetyl pyridine. The cobalt(II) and copper(II) complexes were isolated in their solid state by the direct reactions of ligand ,L with CoCl2.6H2O and CuCl2•2H2O solutions. The structure and geometry of the metal complexes were determined their chemical structures on the basis of (CHNS) elemental analyses, FT-IR,LC-MS and UV-Visible spectra beside the measurements of magnetic susceptibility at room temperature and molar conductance in DMSO solvent. The application part of the recent paper was the screening of the new poly dentate-based pyrazoline ligand and its CoL and CuL complexes with thymus DNA act as powerful sequence-specific gene modulators, by exerting their effect from transcription regulation to gene modification. The DNA binding abilities of the 5-[4-(dimethylamino)phenyl]-3-(2-oxo-2H-chromen-3-yl)-1H-pyrazole-1-carbithioamide and it Cu , Co complexes was evaluated by UV–Vis titration experiments, which was a useful method to calculate the DNA binding constants in vitro. After Calf Thymus DNA (CT DNA) was added to the phosphate buffer solution containing constant ligand and complexes concentrations, all of the solutions exhibited a slight hypochromic without any significant spectral shift. The binding constants of the compounds were calculated by using a plot of D/∆Ɛapp versus D. Close ,Cu and Co showed the largest binding constant (7.8 * 104 , 8 * 108 , 6.1* 103 ) M for binding with DNA respectively . Specifically, both compounds showed hypochromicity upon increasing DNA concentration, indicating that both compounds interacted with the DNA helix. However, a weak hypochromic effect is indeed observed, and no red shift is apparent. In a third part of study ,a series of chromene and its complexes with Co and Cu were synthesized and their acetyl cholinesterase enzyme (AChE) inhibitory effects were investigated. All carben were synthesized from the corresponding carboxylic acids via of the acids with diphenyl phosphoryl azide followed by addition of benzyl alcohol. The chromene and its complexes with Co and Cu were determined to be very good inhibitors against for AChE with different type of inhibition (mix and non-competitive) inhibition.

New Cu(II), Co(II) and Ni(II) azo-Schiff base complexes: Synthesis, characterization, catalytic oxidation of alkenes and DFT study

Three new complexes with general formula of ML (M = Cu (1), Co (2), Ni (3)) containing an azo-Schiff base ligand (H2L) derived from 2,3-butanediamine and 4-(benzeneazo) salicylaldehyde were synthesized by template method. Characterization of the ligand and complexes were accomplished with FT-IR, UV–Vis, and 1H NMR. The catalytic activity of the complexes (1–3) were tested for the oxidation of various alkenes (cyclooctene, cyclohexene, styrene, α-methyl styrene, and norbornene) applying tert-butyl hydroperoxide (TBHP) as an oxidizing agent, and it was found that they were acceptable catalysts. Under the optimized reaction conditions, CuL complex displayed 94% conversion for the oxidation of cyclooctene, and CoL and NiL complexes exhibited 90 and 85% conversions for oxidizing α-methyl styrene, respectively. Based on our density functional computations, diffuse functions are compulsory in the basis set for geometry optimization of these systems. Therefore, the most stable structures and the vibrational frequencies were calculated at the M06-2X/6–311++G(d,p) level. By establishing the correlation between observed and calculated frequencies, the assignment of the vibrational modes was performed. Based on natural charge analysis (NAO), the back electron transfer from ML to the TBHP breaks the OO bond and facilitates the formation of tert-butoxyl radicals.