Cobalt Schiff Base Complexes Research Articles

Transfer Hydrogenation of Vinyl Arenes and Aryl Acetylenes with Ammonia Borane Catalyzed by Schiff Base Cobalt(II) Complexes.

A series of bench-stable Co(II) complexes containing hydrazone Schiff base ligands were evaluated in terms of their activity and selectivity in carbon-carbon multiple bond transfer hydrogenation. These cobalt complexes, especially a Co(II) precatalyst bearing pyridine-2-yl-N(Me)N=C-(1-methyl)imidazole-2-yl ligand, activated by LiHBEt3, were successfully used in the transfer hydrogenation of substituted styrenes and phenylacetylenes with ammonia borane as a hydrogen source. Key advantages of the reported catalytic system include mild reaction conditions, high selectivity and tolerance to functional groups of substrates.

Recent developments on the synthesis of copper and cobalt-Schiff base complexes and their assessment as anti-tuberculosis drugs

Recent developments on the synthesis of copper and cobalt-Schiff base complexes and their assessment as anti-tuberculosis drugs

Theoretical studies and evaluation of anticancer properties of two cobalt(III) Schiff base complexes derived from 3,5-dichloro-2-hydroxybenzaldehyde and 1,2-phenylene diamine

This research aimed to synthesize a tetradentate symmetrical ligand, H2L, through the condensation reaction between 3,5-dichloro salicylaldehyde and 1,2-phenylenediamine. The produced ligand contains [N2O2] donor atoms and forms two new Co(III) Schiff base complexes, namely [CoIII(L)(1-MeIm)2]ClO4 (1) and [CoIII(L)(mrpln)2]ClO4 (2). Then, the structural characterization of these compounds was further examined by experimental techniques such as single x-ray diffraction, CHNS analysis, FT-IR spectroscopy, UV–Vis spectroscopy, and theoretical quantum chemical calculations. Furthermore, the structure's HOMO-LUMO energy gap and molecular electrostatic potential (MEP) were measured using the B3LYP/6–311 G method and compared to experimental data. Hirshfeld surface analysis was employed to investigate intermolecular interactions inside the crystal structures. Subsequently, an investigation was conducted to examine the biological characteristics of the ligand (H2L) and its complexes about SW-480 cancer cells, revealing significant anti-cancer effects. Molecular docking assessments were performed on both complexes to determine their propensity for binding the protein B-cell lymphorna (BCL-2, PDB ID: 4LXD).

An impactful approach for visible photocatalytic reduction of CO2 accelerated with Schiff base-cobalt complex

An impactful approach for visible photocatalytic reduction of CO2 accelerated with Schiff base-cobalt complex

Synthesis, crystal structure, thermal properties of a homoleptic Schiff base cobalt complex bis(N-tert-pentyl salicylaldimine)cobalt(II) as precursor for coating Co3O4 thin film by a plasma enhanced MOCVD

A Schiff base complex of cobalt namely, bis(N-tert-pentyl-salicylaldimine)cobalt(II) (2) was synthesized by treating the parent complex, bis(salicylaldehydato)cobalt(II) (1) with n-tert-pentylamine in a methanolic medium. Complex 2 was analysed by dynamic TG/DTA using high purity Ar as purge gas at ambient pressure and was found to be volatile without undergoing decomposition leaving a negligible amount of (1.8 %) residue at 322 °C after melting sharply at 155 °C. The parent complex (1) wherein four oxygen atoms are coordinated to cobalt yielded a residue of 58 % at 400 °C. The dissimilarity in thermal property of 2 (CoN2O2) from that of 1 (CoO2O2) arises from the bonding of nitrogen atoms to cobalt by introducing n-tert-pentylamine which caused replacement of aldehyde O (–CH = O) with azomethine nitrogen (–CH = N). Single crystal XRD analysis of complex 2 revealed it to crystallise in orthorhombic crystal system with a space group of P212121. Further 2 was characterised by FTIR, elemental analysis and mass spectrometry. Transpiration TG technique was employed to evaluate the temperature dependence of saturated vapour pressure (pe) and enthalpy of vaporization (ΔvapH° = 102.3 ± 2.5 kJ mol−1) for 2 in the temperature range of 443–545 K. Complex 2 was transformed in to Co3O4 thin film at 350 °C in an Ar plasma by using a lab made plasma assisted chemical vapour deposition (CVD) process at 1.2 mbar deposition pressure. XRD revealed a preferential growth of cubic Co3O4 in the (311) plane. The SEM images confirmed a dense but scattered growth of cauliflower shaped structures. The particle size was found to be 19.3 nm. Kubelka-Munk function yielded a band gap of 2.01 eV.

Synthesis, crystal structures and anticancer studies of Ni (Ⅱ), Co (Ⅲ) and Zn (Ⅱ) complexes based on 5-bromosalicylaldehyde- 2-(2-aminophenyl)benzimidazole Schiff base

Three metal complexes [Ni2 (HL)2 (C2H5OH)2 Cl2]·2C2H5OH (complex 1), [Co (HL) (L)] (complex 2) and [Zn2 (HL)2 (CH3COO)2] (complex 3) derived from 5-bromosalicylaldehyde-2-(2-aminophenyl)benzimidazole Schiff base ligand (H2L) were synthesized and characterized by infrared (IR) spectroscopy, thermogravimetric (TG) analysis and powder X-ray diffraction (XRD). Single crystal X-ray diffraction analysis confirmed that complex 1 crystallized in binuclear octahedral structure with space group P21/C and complex 2 displayed in mononuclear octahedral structure with space group P 121/c 1. While complex 3 produced binuclear pyramid structure with space group P 121/c 1. Herein, cobalt (Ⅱ) salt was oxidized to form Schiff base cobalt (Ⅲ) complex by coordinating three deprotonated groups. The MTT method was employed to determine the three complexes in vitro cytotoxicity effects against human lung cancer cells (A-549), liver cancer cells (SMMC-7721), breast cancer cells (MDA-MB-231) and nasopharyngeal carcinoma cells (CNE-2Z). The results showed that Co (Ⅲ) complex has significant anticancer activity against human breast cancer MDA-MB-231 cells compared with cisplatin. The further study of its anticancer mechanisms exhibited that Co (Ⅲ) complex could inhibit MDA-MB-231 cells proliferation through both apoptosis and DNA replication inhibition.

Corrosion inhibition of Schiff base and their metal complexes with [Mn (II), Co (II) and Zn (II)]: Experimental and quantum chemical studies

The synthesis, characterization, and examination of anti-corrosion performance of 2-furaldehyde semicarbazone Schiff base (FSC) complexes of cobalt (II), zinc (II), and manganese (II) on XC38 carbon steel immersed in 1 M HCl solution are performed using experimental investigations and quantum chemical simulation approaches. The theoretical approach used were DFT calculations and MC simulation. The inhibition effect was also studied by electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP). Electrochemical testing results show that these chemical compounds are particularly powerful inhibitors, which FSC-Mn provides a considerable inhibition of 91.48%at 500 ppm. The results also demonstrate that the inhibition effect of the four inhibitors increased with increasing inhibitor concentration, revealing that these compounds adsorb significantly to the steel surface. The scanning electron microscopy (SEM) analyses indicated that FSC and its complexes adsorbed onto the surface of XC38 carbon steel by forming a barrier between the inhibitors and the vacant d-orbital of iron. Quantum investigations were consistent with experimental findings on the four inhibitors’ capacity to prevent XC38 carbon steel from corroding in 1 M HCl, which were also proven effective as cathodic and anodic type inhibitors, displacing water molecules from mild steel, and producing heterogeneous coatings on the XC38 carbon steel surface to defend against corrosion.

The Transfer Hydrogenation of Cinnamaldehyde Using Homogeneous Cobalt(II) and Nickel(II) (E)-1-(Pyridin-2-yl)-N-(3-(triethoxysilyl)propyl)methanimine and the Complexes Anchored on Fe3O4 Support as Pre-Catalysts: An Experimental and In Silico Approach

The imino pyridine Schiff base cobalt(II) and nickel(II) complexes (C1 and C2) and their functionalised γ-Fe3O4 counterparts (Fe3O4@C1 and Fe3O4@C2) were synthesised and characterised using IR, elemental analysis, and ESI-MS for C1 and C2, and single crystal X-ray diffraction for C1, while the functionalised materials Fe3O4@C1 and Fe3O4@C2 were characterized using IR, XRD, SEM, TEM, EDS, ICP-OES, XPS and TGA. Complexes C1, C2 and the functionalised materials Fe3O4@C1 and Fe3O4@C2 were tested as catalysts for the selective transfer hydrogenation of cinnamaldehyde and all four pre-catalysts showed excellent catalytic activity. Complexes C1 and C2 acted as homogeneous catalysts with high selectivity towards the formation of hydrocinnamaldehyde (88.7% and 92.6%, respectively) while Fe3O4@C1 and Fe3O4@C2 acted as heterogeneous catalysts with high selectivity towards cinnamyl alcohol (89.7% and 87.7%, respectively). Through in silico studies of the adsorption energies, we were able to account for the different products formed using the homogeneous and the heterogeneous catalysts which we attribute to the preferred interaction of the C=C moiety in the substrate with the Ni centre in C2 (-0.79 eV) rather than the C=O (-0.58 eV).

Copper(ii) and cobalt(iii) Schiff base complexes with hydroxy anchors as sensitizers in dye-sensitized solar cells (DSSCs).

Two Schiff base complexes of copper(ii) and cobalt(iii) having the formulae [CuL2] (Cu-Sal) and [CoL3] (Co-Sal) (HL = 2-(((2-hydroxyethyl)imino)methyl)phenol) have been synthesized and characterized microanalytically, spectroscopically and in the case of Cu-Sal using single crystal X-ray diffraction technique. The single crystal X-ray analysis reveals a square planar geometry around Cu(ii) satisfied by phenoxide oxygen and imine nitrogen of the L- ligand to generate a six membered chelate ring. The solid state structure of Cu-Sal is satisfied by varied intermolecular non-covalent interactions. The nature of these interactions has been addressed with the aid of Hirshfeld surface analysis. Both compounds have been used as sensitizers in TiO2 based dye sensitized solar cells (DSSCs) and the DSSC experiments revealed that Co-Sal offers better photovoltaic performance in comparison to Cu-Sal. The Co-Sal exhibited a J sc of 9.75 mA cm-2 with a V oc of -0.648 V, incident photon to current conversion efficiency (IPCE) of 57% and η of 3.84%. The relatively better photovoltaic performance of Co-Sal could be attributed to better light absorption and dye loading than that of Cu-Sal.

Novel Schiff Base Co(II) Complexes: Potential Biological Applications

Cobalt (Co) complexes with the N2O2 category have been created synthetically by the reaction of salicylaldehyde / 3,4-diamino benzophenone with acetylacetone and glutaric anhydride respectively. The ligands and individual Cobalt (II) complexes were recognized through spectroscopical data (Fourier Transform Infrared, Ultra Violet-visible, proton and carbon-13 NMR, & Mass). Non-electrolytic in nature of the complex found from their molar conductivities (Ω-1cm2mol-1) in DMSO of 10-3M solution. The ESR revealed the geometry of the complexes to be octahedral. The Schiff base Cobalt (II) complex was characterized by anticancer activity and cytotoxicity

A significantly non-toxic novel Cobalt(III) Schiff base complex induces apoptosis via G2-M cell cycle arrest in human breast cancer cell line MCF-7

AimsMetal complexes have ignited considerable interest in the field of chemotherapy after the serendipitous discovery of cisplatin but the severe toxicity of these platinum-based drugs compelled researchers to search for newer, more effective lesser toxic anticancer drugs. Materials and methodsStructural analysis is done by different physicochemical techniques including X-ray single crystallography. Toxicity study has been done in normal Swiss albino mice. MTT assay assessed cell viability. Apoptosis, cell cycle arrest, and cell proliferation were assessed by FACS using Annexin V-PI, PI, and CFSE staining respectively. Western blot quantifies protein expression. While cell migration was studied by wound healing assay. Key findingsOne-pot synthesis of a novel mononuclear cobalt(III)-Schiff base complex (1) (>99 % purity) and its complete characterization have been done. Cell viability assay showed that 1 (IC50 = 16.81 ± 1.33 μM) exhibits cytotoxicity at much lower concentration in comparison to oxaliplatin (IC50 = 31.4 ± 0.69 μM) against MCF-7 cells for 24 h of therapy without being overly toxic to human PBMCs (IC50 ≥ 60 μM). Additional in vitro studies demonstrated that 1 induces apoptosis via G2-M cell cycle arrest and reduces cell proliferation as well as cell migration in MCF-7 cells. In vivo subacute toxicity (28 days) and systemic chronic toxicity (40 days) studies were carried out in normal Swiss albino mice showed 1 is significantly nontoxic to the host. SignificanceThe readily synthesizable, significantly nontoxic cobalt complex with appreciable anticancer activity implies that it might be an effective chemotherapeutic agent for new-age anti-tumor medication.

Synthesis, Structural Elucidation, Cytotoxic activity and Plant Growth Studies of Some Novel Schiff Base Cobalt(II) and Nickel(II) Complexes of Sulfur/Oxygen and Nitrogen Donor Agents

Eight metal complexes with Schiff base ligands, HL1 [2-{1-(2-fluorophenyl)ethyledene}] hydrazinecarboxamide and HL2 [2-{1-(2-fluorophenyl)ethyledene}] hydrazinecarboxathioamide were synthesized with Co(II) and Ni(II). These were characterized by analytical as well as various spectroscopic techniques like FT-IR, 1H NMR, electronic absorption spectra. The spectral results revealed the formation of octahedral complexes. To determine the concentration of cobalt in Schiff base metal complex flame atomic absorption spectroscopy (FAAS) was done. The accuracy of results was verified by inductively coupled plasma mass spectroscopy (ICP-MS). In vitro cytotoxic activity of the ligands HL1, HL2 and their Schiff base metal complexes was examined, in which A549 (human lung cancer cell line) and L929 (mouse normal fibroblast cell line) were used in the screening test. Among all the synthesized Schiff base ligands and metal complexes, Ni(II) thiosemicarbazone based complex i.e. (Ni (L2)2.2H2O) exhibited a significant cytotoxic effect towards A549 cell line with a mean IC50 value of 36.43 μΜ. Plant growth regulatory activity of the ligands (HL1, HL2) and their metal complexes have also been performed on chick pea plant. The PGR activity of the ligands and their complexes were compared and it was found that the thiosemicarbazone based metal complexes possess higher PGR activity.

Field-Induced Single Molecule Magnetic Behavior of Mononuclear Cobalt(II) Schiff Base Complex Derived from 5-Bromo Vanillin

A mononuclear Co(II) complex of a Schiff base ligand derived from 5-Bromo-vanillin and 4-aminoantipyrine, that has a compressed tetragonal bipyramidal geometry and exhibiting field-induced slow magnetic relaxation, has been synthesized and characterized by single crystal X-ray diffraction, elemental analysis and molecular spectroscopy. In the crystal packing, a hydrogen-bonded dimer structural topology has been observed with two distinct metal centers having slightly different bond parameters. The complex has been further investigated for its magnetic nature on a SQUID magnetometer. The DC magnetic data confirm that the complex behaves as a typical S = 3/2 spin system with a sizable axial zero-field splitting parameter D/hc = 38 cm−1. The AC susceptibility data reveal that the relaxation time for the single-mode relaxation process is τ = 0.16(1) ms at T = 2.0 K and BDC = 0.12 T.

Degradation of dye wastewater by using cobalt, copper and nickel Schiff base complexes as catalysts: spectral, molecular modelling, catalytic activity and metal removal from aqueous solution

ABSTRACT Metal complexes of Co(II), Cu(II) and Ni(II) with the Schiff base ligand, 6,6ʹ-(([1,1ʹ-biphenyl]-4,4ʹ diylbis(azaneylylidene))bis(methaneylylidene))bis(2,4-dichlorophenol) (H2L) were synthesised. All synthesised compounds were identified and characterised. The conductivity measurements showed the non-electrolytic nature of all the complexes. The decomposition of all complexes ended with metal oxide. Octahedral geometries were proposed for all complexes. Photocatalytic degradation of methylene blue dye (MB) in the presence and absence of hydrogen peroxide was studied by using Co(II), Cu(II) and Ni(II) complexes as catalysts. Fluorescence studies have shown that the reported compounds can act as photoactive materials. Density functional theory was used to investigate the geometries of the ligand and its complexes. The adsorption of Co2+, Ni2+ and Cu2+ in an aqueous solution on H2L ligand under various conditions was studied. The optical properties of all complexes were studied. Antimicrobial activities of the ligand and its transition metal complexes were studied. The in-vitro cytotoxicity of ligand and its cobalt(II), nickel(II) and copper(II) complexes were evaluated towards the human Liver Carcinoma (HepG2) cell line and compared with standard cisplatin.

Cytotoxic cobalt (III) Schiff base complexes: in vitro anti-proliferative, oxidative stress and gene expression studies in human breast and lung cancer cells.

Increasing cancer drug chemo-resistance, especially in the treatment of breast and lung cancers, alarms the immediate need of newer and effective anticancer drugs. Until now, chemotherapeutics based on metal complexes are considered the most effective treatment modality. In the present study, we have evaluated the cytotoxic effect of two cobalt (III) Schiff base complexes based on the leads from complex combinatorial chemistry. Cobalt (III) Schiff base complexes (Complex 3=Co(Ph-acacen)(HA)2](ClO4) and Complex 4= [Co(Ph-acacen)(DA)2](ClO4)] (Ph-acacen, 1-phenylbutane-1,3-dione; DA, dodecyl amine; HA, heptylamine) were evaluated against human breast cancer cell MCF-7 and lung cancer cell A549 using MTT cell viability assay, cellular morphological changes studied by Acridine Orange and Ethidium Bromide (AO/EB), Dual fluorescent staining, Hoechst staining 33248, Comet assay, Annexin V-Cy3 and 6 CFDA assay, JC-1 staining, Reactive oxygen species (ROS) assay, Immunofluorescence assay, and Real-time reverse transcription-polymerase chain reaction (RT-qPCR). Treatment of cobalt (III) Schiff base complexes (Complex 3 & 4) affected the viability of the cancer cells. The cell death induced by the complexes was predominantly apoptosis, but necrosis also occurred to a certain extent. Complex 4 produced better cytotoxic effect than complex 3, and MCF-7 cell was more responsive than A549. In that order, the complexes were more selective to cancer cell than normal cell, and more effective in overall performance than the standard drug cisplatin. Therefore, we conclude that cobalt (III) Schiff base complexes, especially complex 4, have the potential to be developed as effective drugs for treatment of cancers in general, and breast and lung cancers in particular.

Radioprotective effect of a novel and green bio-nanohybrid, chitosan/silver/cobalt complex, based on Ferulago angulate plant.

A novel bio-nanocomposite was developed by incorporating the extracted nanochitosan from shrimp wastes with Schiff base cobalt complex (Chit-Co complex). The phytosynthesis of Chit-Co complex/Ag bio-nanocomposite was designed utilizing Chit-Co complex at the presence of Ferulago angulate extraction and characterized by AFM, SEM, EDAX, TEM, FT-IR, and elemental analysis. The radioprotective application of this bio-nanocomposite on human lymphocyte cells was evaluated using micronucleus (MN) assay. Total antioxidant activities of it were evaluated using FRAP and DPPH assays. Chit-Co complex/Ag bio-nanocomposite significantly decreased the frequency of micronuclei in human lymphocytes exposed to ionization irradiation (IR). The highest protection was observed at 200μg/ml. Also, maximum antioxidant activities of bio-nanocomposite were provided at the same dose. These data exhibit the radioprotective effect of a bio-nanocomposite based on wastes of living organisms can be an excellent radioprotective agent, which can protect the normal cells of human against the genetic damage by IR.

Potential application of two cobalt (III) Schiff base complexes in cancer chemotherapy: Leads from a study using breast and lung cancer cells

Cobalt (III) Schiff base complexes are of attraction in the context of their potential application in cancer therapy. The aim of this study has been to find the mechanism of action of cobalt (III) Schiff base complexes 1 and 2, the synthesis and characterization of which have already been reported, in inhibiting growth of human breast cancer cell MCF-7 and lung cancer cell A549. The already proclaimed anti-proliferative effect of the cobalt complexes was ascertained using MTT cytotoxicity assay. More assays such as Acridine orange & Ethidium bromide staining, AnnexinV-Cy3 staining, Hoechst staining, comet assay, and Reactive Oxygen Species (ROS) assay- all supported the cytotoxic property of the complexes. Moreover, the expression levels of mRNA of pro- and antiapoptotic genes also supported the effectiveness of cobalt complexes by modifying the ratio of Bax: Bcl-2. In addition, the cobalt complexes induced apoptosis in MCF- 7 and A549 cells through modulation of pro-apoptotic, anti-apoptotic, and ROS modulatory gene expressions. The present study validates the scientific evidence for antiproliferative efficacy of cobalt complexes against MCF-7 and A549 cells. Thus, this study takes cobalt complexes 1 and 2 to a step higher towards their use as anticancer agents.

Design of a New Poly Imidazolium-Tagged Cobalt (II) Schiff Base Complex for Selective Oxidation of Alcohols and Sulfides in a Water Solvent

In this study, a new catalyst including polymeric imidazolium ionic liquid functionalized Cobalt (II) Schiff base complex [PIL-SB-Co (II)] was prepared and characterized using various analyses like FT-IR, H-NMR, FE-SEM, Energy-dispersive X-ray, thermogravimetric analysis, and ICP-OES. Then, its catalytic activity was studied in oxidation reaction of sulfides and alcohols. This polymeric heterogeneous catalyst can catalyze the oxidation reactions in water as a green solvent, and mild conditions (room temperature) with good to excellent yields of sulfoxides, aldehydes, and ketones as worthwhile and critical products. Highlights First preparation and characterization of poly ionic liquid functionalized Co (II) Schiff base catalyst. First oxidation reaction of sulfides and alcohols catalyzed by polymeric ionic liquid Schiff base complex. Oxidation reaction of sulfides and alcohols to sulfoxides and aldehydes and ketones in water as a green solvent and room temperature. Reusable catalyst at least for five runs.

Retraction notice to “Cobalt Schiff base complexes: Synthesis characterization and catalytic application in Suzuki-Miyaura reaction” [Chin. J. Chem. Eng. 27(3) (2019) 556–563

Retraction notice to “Cobalt Schiff base complexes: Synthesis characterization and catalytic application in Suzuki-Miyaura reaction” [Chin. J. Chem. Eng. 27(3) (2019) 556–563

A novel Schiff base cobalt(III) complex induces a synergistic effect on cervical cancer cells by arresting early apoptosis stage

A new schiff base cobalt(III) complex [N,N'-bis(2'-hydroxyphenylacetone)-o-ethanediamine] cobalt(III) (M3) has been synthesized and characterized by single X-ray crystallography. The cytotoxicity of complex M3 was evaluated against HeLa, LoVo, A549, A549/cis cancer cell lines, and the normal cell lines LO2 by MTT assays. The IC50 is in the range of 6.27-22.68μM, which is somewhat lower than cisplatin on the basis of platinum molar concentration. Furthermore, anticancer mechanistic studies showed that the complex M3 inhibited cell proliferation by blocking DNA synthesis and then acted on nuclear division of HeLa cells over time. Moreover, western blot analysis indicated M3 dramatically decreased the target protein c-Myc and KLF5 expression levels, and activated many signaling pathways including ER stress, apoptosis, cell cycle and DNA damage in HeLa. M3 did not affect proteasomal activity.