Preparation,characterization, DFT calculations and ethylene oligomerization studies of iron(II) complexes bearing 2-(1H-benzimidazol-2-yl)-phenol derivatives

Five 2-(1H-benzimidazol-2-yl)-phenol derivatives including 1H (HL₁), 5-chloro-(HL₂), 5-methyl-(HL₃), 5,6-dichloro-(HL₄), and 5,6-dimethyl-(HL₅) were synthesized by the reaction of their corresponding benzene-1,2-diamine precursors and 2-hydroxybenzaldehyde which subsequently was employed in complexation with Fe(II) to prepare complexes C1–C5, respectively. Indeed, in all complexes, the ligands were coordinated as bidentate, via the C=N nitrogen and hydroxy oxygen atom of benzimidazole moiety and phenol ring, respectively. The compounds were characterized by FTIR, UV–vis, ¹H- and ¹³C-NMR spectropscopy, ICP, and elemental analysis (C, H, and N). The purity of these compounds was determined by melting point (m.p )and TLC. The synthesized ligands and complexes were geometrically optimized by Gaussian09 software at B3LYP/TZVP level of theory and satisfactory theoretical–experimental agreement was achieved for analysis of IR data of the compounds. Catalytic behavior of the iron(II) complexes was investigated for ethylene reactivity. On activation with diethylaluminum chloride (Et₂AlCl), iron(II) complex (C4) showed the highest activity (1686 kg oligomers.mol^?1(Fe).h^?1) for ethylene oligomerization when it contains chlorine substituents and exhibits good selectivity for linear 1-butene. The steric and electronic effects of ligands were investigated in detail on the influence of their catalytic activities.     

Two 1-D and 2-D cobalt(II) complexes: synthesis,crystal structures,spectroscopic and electrochemical properties

Two new cobalt(II) complexes, [Co(L³)₂]·CH₃OH·CH₃COCH₃ (1) (HL³ = 1-(2-{[(E)-3,5-dichloro-2-hydroxybenzylidene]amino}phenyl)ethanone oxime) and Co(L⁴)₂ (2) (HL⁴ = 1-(2-{[(E)-3,5-dibromo-2-hydroxybenzylidene]amino}phenyl)ethanone oxime), have been synthesized via complexation of Co(II) acetate tetrahydrate with HL¹ and HL². HL¹, HL², and their corresponding Co(II) complexes were characterized by IR, ¹H NMR spectra, as well as by elemental analysis and UV–Vis spectroscopy, respectively. The crystal structures of the complexes have been determined by single-crystal X-ray diffraction. 1 and 2 display that extensive hydrogen bonds and C–X···π bonding interactions construct the 1-D infinite chain [Co(L³)₂]·CH₃OH·CH₃COCH₃ and Co(L⁴)₂ into 2-D supramolecular frameworks. The electrochemical properties of two Co(II) complexes were also investigated by cyclic voltammetry.     

The Interaction of α‐Hydroxycarboxylic Acids with Metal Ions: Lactic Acid (H2L1) and 2‐Methyllactic Acid (H2L2) with Cobalt(II) Crystal and Molecular Structures of [Co(HL1)2(H2O)2]·H2O and [Co(HL2)2(H2O)2]

The cobalt(II) complexes [Co(HL¹)₂(H₂O)₂]·H₂O) ( 1 ) and [Co(HL²)₂(H₂O)₂]( 2 ) [(HL¹)^‐ = (/plusmn;)‐lactate, (HL²)^‐ = 2‐Methyl‐lactate] were prepared and characterized structurally. The cobalt atom is in a distorted octahedral environment in both compounds. Both α‐hydroxycarboxylato ligands are O, O'‐bidentate chelating monoanions. The presence of a lattice water molecule in 1 makes its supramolecular organization different from that of 2 . The thermal behaviour of both compounds was also investigated.     

Synthesis,structures, and urease inhibition of nickel(II), zinc(II), and cobalt(II) complexes with similar hydroxy-rich Schiff bases

Four new nickel(II), zinc(II), and cobalt(II) complexes, [Zn(L¹)₂]?·?H₂O (1), [Ni(L¹)₂]?·?H₂O (2), [Ni(L²)₂] (3), and [Co(L³)₂]?·?H₂O (4), derived from hydroxy-rich Schiff bases 2-{[1-(5-chloro-2-hydroxyphenyl)methylidene]amino}-2-methylpropane-1,3-diol (HL¹), 2-{[1-(2-hydroxy-3-methoxyphenyl)methylidene]amino}-2-ethylpropane-1,3-diol (HL²), and 2-{[1-(5-bromo-2-hydroxyphenyl)methylidene]amino}-2-methylpropane-1,3-diol (HL³) have been synthesized and characterized by elemental analyses, infrared spectroscopy, and single-crystal X-ray determination. Each metal in the complexes is six-coordinate in a distorted octahedral coordination. The Schiff bases coordinate to the metal atoms through the imino N, phenolate O, and one hydroxyl O. In the crystal structures of HL¹ and the complexes, molecules are linked through intermolecular O–H···O hydrogen bonds, forming 1-D chains. The urease inhibitory activities of the compounds were evaluated and molecular docking study of the compounds with the Helicobacter pylori urease was performed.     

Manganese(II) complexes of hydrazone based NNO-donor ligands and their catalytic activity in the oxidation of olefins

The reaction between tridentate NNO donor hydrazone ligands, (E)-2-cyano-N′-(phenyl(pyridin-2-yl)methylene)acetohydrazide (HL¹) and (E)-2-cyano-N′-(1-(pyridin-2-yl)ethylidene)acetohydrazide (HL²), with MnCl₂·4H₂O in methanol resulted in [Mn(HL¹)Cl₂(CH₃OH)] (1) and [Mn(HL²)Cl₂(CH₃OH)] (2). Molecular structures of the complexes were determined by single-crystal X-ray diffraction. All of the investigated compounds were further characterized by elemental analysis, FT-IR, TGA, and UV–Vis spectroscopy. These complexes were used as catalysts for olefin oxidation in the presence of tert-butylhydroperoxide (TBHP) as an oxidant. Under similar experimental conditions with equal manganese loading, the presence of [Mn(HL²)Cl₂(CH₃OH)] (2) resulted in higher conversion than [Mn(HL¹)Cl₂(CH₃OH)] (1).     

Octahedral Co(II) and Ni(II) complexes of Schiff bases,semicarbazone and thiosemicarbazone,synthesis, biological,spectral, and thermal studies

A new series of cobalt(II) and nickel(II) complexes, [M(ligand)(H₂O)₂(Y)] (M = Co(II) or Ni(II); Y = Cl^?, Br^? or NO₃ ^?), containing the Schiff-base semicarbazone and thiosemicarbazone, HL¹ and HL², formed from 4-hydroxycoumarin-3-carbaldehyde have been synthesized. The nature of bonding and the stereochemistry of the complexes have been deduced from elemental analyses, infrared, electronic spectra, magnetic susceptibility, and conductivity measurements. An octahedral geometry has been suggested for the complexes. The metal complexes were screened for their antifungal and antibacterial activities on different species of pathogenic fungi and bacteria and their biopotency has been discussed.     

Coordination compounds of copper with 2-formylpyridine 4-(dimethylphenyl)thiosemicarbazones

2-Formylpyridine 4-(2,6-dimethylphenyl)-(HL¹), 4-(2,5-dimethylphenyl)-(HL²), 4-(3,4-dimethylphenyl)-(HL³), and 4-(2,4-dimethylphenyl)thiosemicarbazones (HL⁴) react with copper chloride and nitrate to form coordination compounds CuL^1–4X·nH₂O [X = Cl^?, NO ₃ ^? ; n = 1, 2]. All compounds have a polynuclear structure. Azomethines HL^1–4 act as the bridging monodeprotonated tridentate N,N,S-ligands. The thermolysis of the complexes includes the dehydration (70–90°C) and total thermal decomposition (350–520°C). The complexes synthesized exhibit a selective antimicrobial activity against a series of standard strains of Staphylococcus aureus and Escherichia coli in the concentration range of 0.009–37.5 μg ml^?1.     

Nitrocellulose Membrane,Modified by RC(S)NHP(X)(OiPr)2 (X = S,R = PhNH; X = O,R = PhNH,Ph), for Sorption Extraction of Cobalt Cations

The complexation and extraction properties of RC(S)NHP(X)(OiPr)₂ [X = S, R = PhNH (HL^I); X = O, R = PhNH (HL^II), Ph (HL^III)] towards cobalt cations were studied. The nitrocellulose membrane was used as a carrier for HL^I?III. The maximal degree of extraction of cobalt cations from an aqueous solution is observed at pH = 7.8–8.4. It was established that complexes formed are kept in a water solution on a surface of the carrier and washed away in 96% aqueous ethanol. The membrane modified by HL^I allows extraction and concentration of Co(II) selectively, while the modification by HL^III leads to the selective extraction of Co(III).     

Complexes of Co(II) and Zn(II) with N-(Thio)phosphorylthioureas AdNHC(S)NHP(O)(OiPr)2 and MeNHC(S)NHP(S)(OiPr)2

The reaction of the potassium salt of the N-(thio)phosphorylated thioureas AdNHC(S)NHP(O)(OiPr)₂ (HL^I , Ad = Adamantyl) and MeNHC(S)NHP(S)(OiPr)₂ (HL^II ) with Co(II) and Zn(II) in aqueous EtOH leads to [ML^I,II ₂] chelate complexes. They were investigated by UV-vis, ¹H and ³¹P NMR spectroscopy, and microanalysis. The molecular structures of [ML^I ₂] were elucidated by single crystal X-ray diffraction analysis. The metal centers in both complexes are found to be in a distorted-tetrahedral O₂S₂ environment formed by the C=S sulfur atoms and the P=O oxygen atoms of two deprotonated L^I ligands. The photoluminescence properties of [ZnL^II ₂] are also reported.     

Effect of Structure and Composition of Copper and Cobalt Complexes with Schiff Base Ligands on their DNA/Protein Interaction and Cytotoxicity

Four transition metal complexes, namely Cu₂Cl₂(HL¹)₂ ( 1 ), Co(HL¹)₂ ( 2 ), Cu(HL²)₂ ( 3 ), Co(HL²)₃ ( 4 ) {H₂L¹ = 2‐{[2‐(2‐hydroxy‐ethoxy)‐ethylimino]‐methyl}‐phenol, H₂L² = 3‐{[2‐(2‐hydroxy‐ethoxy)‐ethylimino]‐methyl}‐naphthalen‐2‐ol} were synthesized and characterized by single‐crystal X‐ray diffraction, IR spectroscopy, and elemental analysis. The interactions of these copper and cobalt complexes with calf thymus DNA (CT‐DNA) were studied by absorption and emission titration spectroscopic methods. The interactions of these copper and cobalt complexes with bovine serum albumin (BSA) were also investigated using fluorescence, UV/Vis, and synchronous fluorescence spectroscopy. Further, the in vitro cytotoxic effect of the complexes are examined on human colon carcinoma cell lines (HCT‐116) and human lung carcinoma cell line (A549).     

Synthesis,structure, geometrical,and spectral characteristics of the (HL<Superscript><Emphasis Type="Italic">n</Emphasis></Superscript>)<Subscript>2</Subscript>[CuCl<Subscript>4</Subscript>] complexes. Crystal and molecular structure of bis(2-methylimidazolium) tetrachlorocuprate(II)

The (HL ⁿ )₂[CuCl₄] complexes (where L ⁿ are organic nitrogen-containing bases with n = 1–6) were synthesized. The crystal and molecular structures of bis(2-methylimidazolium) tetrachlorocuprate(II), (HL¹)₂[CuCl₄], were determined. The spectral characteristics of the complexes were measured. The correlations between the degree of distortion of the crystal structure of the tetrachlorocuprate anion and the hydrogen bond parameters and the spectral characteristics of compounds were obtained.     

Chemical and Electrochemical Preparation for Co(II) Complexes of Some Novel Pyridine-2-(1H)-Thione Ring Fused Cycloalkane Derivatives

Anodic oxidation of cobalt and copper metals in an anhydrous acetone solution of pyridine-2-(1H)-thione-3-cyano-4-(2-bromophenyl)-5,6-ring fused cycloheptane (HL¹) and its derivatives, (HL²), (HL³), (HL⁴), (HL⁵), (HL⁶), (HL⁷), (HL⁸), and (HL⁹) yields complexes of composition [M(L)₂·(H₂O)₂]·n H₂O and [M(L)₂·(acetone)₂], where M = Co(II) or Cu(II) and L is the ligand. Also, reaction of an aqueous ethanolic solution of Co(Ac)₂·2H₂O with the previous ligands was prepared. Elemental analysis, and infrared and electronic spectral data are presented to confirm the formulation of the amorphous complexes. The spectral data indicate that the ligands are coordinated to the metal via the thioenol sulfur atom and the nitrogen atom of cyano groups. The ligands reacts in the enol form through the anodic dissolution of the ligands or during the reaction with metal salts. The ligand field parameters and crystal field splitting energies, Δ_o, for different cobalt metal complexes were calculated.     

New homoleptic metal complexes of Schiff bases derived from 2,4-di-p-tolyl-3-azabicyclo[3.3.1]nonan-9-one

New bidentate Schiff-base ligands 2-(2,4-di-p-tolyl-3-azabicyclo[3.3.1]nonan-9-ylidene)hydrazinecarbothioamide HL¹ and 2-(2,4-di-p-tolyl-3-azabicyclo[3.3.1]nonan-9-ylidene)hydrazinecarboxamide HL² were synthesized from the condensation of 2,4-di-p-tolyl-3-azabicyclo[3.3.1]nonan-9-one with thiosemicarbazide and semicarbazide, respectively. Homoleptic complexes of these ligands, of general formula K[Cr(L ⁿ )₂Cl₂], K₂[Mn(L ⁿ )₂Cl₂], K₂[Fe(L¹)₂Cl₂] and [M(L ⁿ )₂] (where M = Co(II), Ni(II) Cu(II), Zn(II), Cd(II), and Hg(II) ions; n = 1 or 2) are reported. The mode of bonding and overall geometry of the complexes were determined through IR, UV-Vis, NMR and mass spectral studies, magnetic moment measurements, elemental analysis, metal content, and conductance. These studies revealed octahedral geometry for Cr(III), Mn(II), and Fe(II) complexes, square planar for Cu(II), Co(II), and Ni(II) complexes and tetrahedral for Zn(II), Cd(II), and Hg(II) complexes.     

Synthesis,characterization, and fluorescence properties of dinuclear cadmium(II) complexes

Four dinuclear cadmium(II) complexes, [Cd₂(L¹)(μ₂-Cl)Cl₂] (1), [Cd₂(L²)(μ₂-Cl)Cl₂] (2), [Cd₂(L³)(μ₂-Cl)Cl₂] (3), and [Cd₂(L⁴)₃ClO₄] (4), where HL¹ = 4-methyl-2,6-bis(1-(2-piperidinoethyl)iminomethyl)-phenol, HL² = 4-methyl-2,6-bis(1-(2-pyrrolidinoethyl)iminomethyl)-phenol, HL³ = 4-methyl-2,6-bis(1-(2-morpholinoethyl)iminomethyl)-phenol and HL⁴ = 4-methyl-2,6-bis(cyclohexylmethyl)iminomethyl)-phenol, were synthesized. They were characterized by elemental analysis, FT-IR, UV–Vis, fluorescence and electronspray ionization mass spectroscopy. Complexes 1 and 4 were also characterized by single crystal X-ray analysis. The cadmiums atoms in 1 are linked by μ₂-chloride in a distorted square pyramidal geometry, whereas cadmium atom in 4 is in a distorted octahedral environment. The complexes show emission bands around 500 nm with excitation at 395 nm.     

两种1,2,3-三唑衍生物的配合物合成策略:晶体结构和表面分析

在不同反应条件下反应得到了两种1,2,3-三唑衍生物的配合物[Co（H₂O）₆][Co（L¹）₃]₂·4H₂O（1）和Cu（L²）₂（2）（HL¹=5-methyl-1-phenyl-1H-1,2,3-triazole-4-carboxylic acid;HL²=1-（4-iodophenyl）-5-methyl-1H-1,2,3-triazole-4-carboxylic acid）。通过X射线单晶衍射和红外光谱确定了晶体结构,同时对配合物1和2进行了表面作用分析（Hirshfeld surface analysis）,在二维指纹图谱中可以清楚的看到配合物中的主要分子间作用。     

Cobalt complexes based on dendritic PAMAM bridged salicylaldimine ligands: Synthesis,characterization and performance in ethylene oligomerization

Two novel dendritic poly(amido-amine) (PAMAM) bridged salicylaldimine ligands were synthesized by Schiff base reaction using 1.0 generation dendritic PAMAM as bridged groups. The cobalt complex with 1,4-butanediamine as core (C1) and the cobalt complex with 1,6-hexanediamine as core (C2) based on dendritic PAMAM bridged salicylaldimine ligands were prepared by metallic coordination reaction, respectively. The structures of the ligands and the dendritic cobalt complexes were characterized by fourier transform infrared (FTIR), ultraviolet spectra (UV), hydrogen nuclear magnetic resonance (¹H NMR) and electrospray ionization mass spectra (ESI-MS). The complexes C1 and C2 were evaluated as catalyst precursors for ethylene oligomerization after being activated with methylaluminoxane (MAO), diethylaluminum chloride (Et₂AlCl), ethylaluminium dichloride (EtAlCl₂) and ethylaluminum sesquichloride (EASC). The dendritic cobalt complexes exhibited the highest activity and selectivity for high carbon oligomers with EASC as activator. Under the conditions of 1.0 MPa, 25°C and Al/Co molar ratio 1500, the catalytic activity and selectivity for C₁₀–C₂₀ using C1 were 3.44×10⁶ g·(mol Co·h)^?1 and 76.53% after activation with EASC, and the catalytic activity and selectivity for C₁₀–C₂₀ using C2 were 3.42×10⁶ g·(mol Co·h)^?1 and 84.50%, respectively.     

Synthesis,crystal structure and catalytic performance of bis (imino)pyridyl nickel complexes

Two new Ni(II) complexes of 2,6-bis[1-(2,6-diethylphenylimino)ethyl]pyridine (L¹), 2,6-bis[1-(4-methylphenylimino)ethyl]pyridine (L² ) have been synthesized and structurally characterized. Complex Ni(L¹)Cl₂?·?CH₃CN (1), exhibits a distorted trigonal bipyramidal geometry, whereas complex Ni(L¹)(CH₃CN)Cl₂ (2), is six-coordinate with a geometry that can best be described as distorted octahedral. The catalytic activities of complexes 1, 2, Ni{2,6-bis[1-(2,6-diisopropyl-phenylimino)ethyl]pyridine} Cl₂?·?CH₃CN (3), and Ni{2,6-bis[1-(2,6-dimethylphenylimino) ethyl]pyridine}Cl₂?·?CH₃CN (4), for ethylene polymerization were studied under activation with MAO.     

Synthesis,structures, and characterization of copper(II), nickel(II), and cobalt(III) metal complexes derived from an asymmetric bidentate Schiff-base ligand

An asymmetric bidentate Schiff-base ligand (2-hydroxybenzyl-2-furylmethyl)imine (L–OH) was prepared. Three complexes derived from L–OH were synthesized by treating an ethanolic solution of the appropriate ligand with an equimolar amount of metallic salt. Three complexes, Cu₂(L–O^?)₂Cl₂ (1), Ni(L–O^?)₂ (2) and Co(L–O^?)₃ (3), have been structurally characterized through elemental analysis, IR, UV spectra and thermogravimetric analysis. Single crystal X-ray diffraction shows metal ions and ligands reacted with different proportions 1?:?1, 1?:?2 and 1?:?3, respectively, so copper(II), nickel(II), and cobalt(III) have different geometries.     

Novel 2-formylpyridine 4-allyl-S-methylisothiosemicarbazone and Zn(II), Cu(II), Ni(II) and Co(III) complexes: Synthesis,characterization, crystal structure,antioxidant, antimicrobial and antiproliferative activity

New zinc (II), copper (II), nickel (II) and cobalt (III) complexes, [Zn (HL)₂]I₂ (1) , [Cu (HL)Cl₂] (2) , [Cu (HL)Br₂] (3) , [Cu (HL)(H₂O)₂](ClO₄)₂ (4) , [Ni (HL)₂]I₂·H₂O (5) , [Co(L)₂]Cl (6) , [Co(L)₂]NO₃ (7) , [Co(L)₂]I·[Co(L)₂](I₃) (8) were obtained with 2-formylpyridine 4-allyl-S-methylisothiosemicarbazone ( HL ). The isothiosemicarbazone ligand was characterized by NMR (¹H and ¹³C), IR spectroscopy and X-ray diffraction. All the complexes were characterized by elemental analysis, IR, UV–Vis, ESI-MS spectroscopy, molar conductivity, magnetic susceptibility measurements. X-ray diffraction analysis on the monocrystal and powder elucidated the structure of the complexes 1 , 5 , 7 and 8 . The ligand and the complexes were tested for their antioxidant and antimicrobial activity against Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae and Candida albicans. Also, the antiproliferative properties of these compounds on human leukemia HL-60, human cervical epithelial HeLa, human epithelial pancreatic adenocarcinoma BxPC-3, human muscle rhabdomyosarcoma spindle, large multinucleated RD cells and normal MDCK cells have been investigated. The nickel complex 5 and cobalt complexes 6 , 7 showed promising antiproliferative activity and low toxicity.