Synthesis,characterization, and anticancer activity of some azole‐heterocyclic complexes with gold(III), palladium(II), nickel(II), and copper(II) metal ions

Four new complexes of Au(III), Pd(II), Ni(II), and Cu(II) ions were synthesized, derived from a novel heterocyclic ligand (L) that has both triazole and tetrazole rings. The ligand synthesis was through successive steps to achieve both heterocyclic rings. The synthesized compounds were characterized using conventional techniques like infrared, ultra violet—visible and proton/carbon nuclear magnetic resonance spectroscopy, metal and thermal analyses, and molar conductivity. All complexes were suggested to have square planar geometry, gold, nickel, and palladium complexes were salts while copper neutral complexes have the chemical formulas; [AuL₂]Cl.2H₂O, [PdL₂]Cl₂.2H₂O, [NiL₂]Cl₂.2H₂O, and [CuL₂]. The cytotoxic effect was studied on breast cancer cell line (MCF‐7 cell line) at different concentrations by using the 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay method, for the ligand (L) and complexes. The results showed that gold(III) and nickel(II) complexes have the highest cytotoxicity among all compounds against cancer cell lines.     

Catalytic oxidative reactions of organic compounds by nitrogen‐containing copper complexes

The dimeric copper(II) complex di‐µ‐chloro‐bis[chloro(di‐3,5‐dimethylpyrazole)copper(II)] (A) in the presence of co‐oxidant hydrogen peroxide acts as a catalyst for the oxidation of benzylic alcohols to give the corresponding aldehydes. In the presence of hydrogen peroxide it also catalyses the oxidation reaction of 2,6‐dimethylphenol to 4,4′‐dihydroxy‐3,5,3′,5′‐tetramethylbiphenyl. The oxidative reactions by bis‐pyridinium tetrachlorocopper(II) (B) in the presence of hydrogen peroxide were compared for similar catalytic reactions of A, and it is observed that B can catalyse the oxidation of aromatic diols, 2,6‐dimethylphenol and thiophenol, but is not suitable for oxidation of benzylic alcohols. Bis‐(N‐phenyl‐3,5‐dimethylpyrazole)copper(II) nitrate monohydrate (C) has a suitable redox potential for one‐electron oxidation. It can oxidize ferrocene to the ferricinium cation, and it can liberate bromine from tetra‐alkylammonium bromides. The complex is catalytically effective for the oxidation of different aromatic and aliphatic aldehydes to the corresponding carboxylic acids. The compound is also effective in transforming benzylic amine to benzylalcohol and benzaldehyde. It can also oxidize diphenylmethane to give benzophenone and diphenylmethanol. It is observed that in each of these complexes a quasi‐reversible Cu(I)–Cu(II) species is present and facilitates the single‐electron oxidation process. Copyright © 2004 John Wiley & Sons, Ltd.     

Nickel versus copper: enhanced antibacterial activity in a series of new nickel(II) Schiff base complexes

Five new Ni(II) Schiff base complexes [NiL^x(Solv)₂] denoted by NiL^x, x = 1–5, were synthesized and characterized. The Schiff base ligands were synthesized from the condensation of 5-bromo-2-hydroxy-3-nitrobenzaldehyde with different aliphatic and aromatic diamines. The X-ray crystal structure of NiL³ was determined. The ligands and complexes were tested as antibacterial agents against two gram(+) and two gram(?) human pathogenic bacteria. The complexes showed moderate antibacterial activity against both gram type bacteria. The new Ni(II) complexes showed enhanced antibacterial activity compared to the previously reported Cu(II) complexes of the same ligands.     

Catalytic activity of some new copper(II) azo-complexes

Copper(II) complexes [Cu(L)₂]?·?nH₂O, where L is 3-(p-X-)-4-hydroxy-l,2-naphthoquinone (for L1, X?=?H; L2, X?=?CH₃; L3, X?=?Cl; L4, X?=?Br; and L5, X?=?NO₂), have been synthesized and characterized by analytical, electrochemical, spectroscopic (IR, UV-Vis, ESR, and ¹H NMR), and magnetic methods. From the data obtained, square-planar geometry has been assigned for all the complexes. [CuL1]?·?H₂O exhibits catalytic activity for oxidation of benzyl alcohol, piperonyl alcohol, and cinnamyl alcohol into their respective aldehydes in the presence of H₂O₂ as co-oxidant and in CH₃CN and H₂O as solvents at room temperature.     

Effect of macrocyclic nickel(II) and copper(II) complexes on the reaction of trypsin with a soybean bioinhibitor

The blocking effect of nickel(II) azamacrocyclic complexes in the biospecific reaction between soybean trypsin inhibitor and trypsin and the absence of such a reaction for related copper(II) complexes were established. The efficiency for inhibition of the formation of the protein adduct was found to depend on the substituents in the macrocyclic ligands. In particular, electron-donor oxygen-containing groups lead not only to efficient blocking of this reaction but also possibly to a considerable change in the conformation of the soybean trypsin inhibitor molecule. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 44, No. 4, pp. 248–253, July–August, 2008.     

Synthesis,spectral and antibacterial activity of Co(II), Ni(II) and Zn(II) complexes with 2‐hydroxy‐benzoic acid(3,4‐dihydro‐2H‐naphthalen‐1‐ylidene)‐hydrazide

A bioactive Schiff base HL i.e. 2‐hydroxy‐benzoic acid(3,4‐dihydro‐2H ‐naphthalen‐1‐ylidene)‐hydrazide was synthesized by reacting equimolar amount of salicylic acid hydrazide and 1‐tetralone. Co(II), Ni(II) and Zn(II) complexes of ligand HL was synthesized in 1:1 and 1:2 molar ratio of metal to ligand. The structure of the synthesized ligand and metal complexes was established by elemental analysis, molar conductance, magnetic susceptibility measurements, electronic, IR and EPR spectral techniques. For determining the thermal stability the TGA has been done. In DFT studies the geometries of Schiff bases and metal complexes were fully optimized with respect to the energy using the 6–31 + g(d,p) basis set. Spectral data reveal that ligand behave uninegative tridentate in ML complexes and uninegative bidentate in ML₂ complexes. On the basis of characterization octahedral geometry has been assigned for Co(II) and Ni(II) complexes, while tetrahedral for Zn(II) complexes. Antibacterial activity of the synthesized compounds were evaluated against Staphylococcus aureus , Bacillus subtilis, Escherichia coli , Xanthomonas campestris and Pseudomonas aeruginosa and the results revealed that metal complexes show enhanced activity in comparison to free ligand.     

Thermal and photochemical reactions of copper(II) dithiocarbamate mixed-ligand complexes with chloroalkanes

Thermal and/or photochemical conversion of a series of copper(II) complexes containing mixed dithiocarbamato–alcohol ligands, Cu^II(Et₂dtc)⁺ . . . Y⁻ (Y=ClO₄⁻, NO₃⁻), into Cu^II(Et₂dtc)Cl in chloroalkane/alcohol solutions, where chloroalkane=CCl₄, CHCl₃ or CH₂Cl₂ and alcohol=MeOH, EtOH or i-BuOH, proceeds in chloroalkanes. Both reactions follow a similar pathway which is more effective the stronger the acceptor properties of chloroalkanes and the weaker the coordinating abilities of alcohols are. A detailed reaction mechanism is proposed which well fits the experimental results obtained by EPR and UV–VIS spectra and quantum yields.     

Cobalt(II), nickel(II), and copper(II) complexes of 14-membered hexaazamacrocycles: synthesis and characterization

Cobalt(II), nickel(II), and copper(II) complexes containing 5,12-di(4-bromophenyl)-7,14-dimethyl-1,2,4,8,9,11-hexaazacyclotetradeca-7,14-diene-3,10-dione (H₂L¹) and 5,12-diphenyl-7,14-dimethyl-1,2,4,8,9,11-hexaazacyclotetradeca-7,14-diene-3,10-dione (H₂L²) have been synthesized. All complexes were characterized by elemental analysis, MALDI TOF-MS spectrometry, and electronic absorption spectroscopy. The crystal structures of two compounds, [Cu₂(H₂L¹)Cl₄]_n and [NiL²], were determined by X-ray powder diffraction. In the polymeric [Cu₂(H₂L¹)Cl₄]_n, the Cu₂Cl₄ units and H₂L¹ molecules are situated on inversion centers. Each Cu(II) has a distorted trigonal-bipyramidal coordination environment formed by N and O from H₂L¹ [Cu–N 2.340(14)?Å, Cu–O 1.952(11)?Å], two bridging chlorides [Cu–Cl 2.332(5), 2.279(5)?Å] and one terminal chloride [Cu–Cl 2.320(6)?Å]. In the [NiL²] complex, the Ni(II) situated on inversion center has a distorted square-planar coordination environment formed by four nitrogens from L² [Ni–N 1.860(11), 1.900(11)?Å].     

The synthesis and characterization of three new vic -dioximes and their nickel(II), copper(II) and cobalt(II) complexes

Three new vic-dioximes, [L¹H₂], N-(4-ethylphenyl)amino-1-acetyl-1-cyclohexenylglyoxime, [L²H₂], N-(4-butylphenyl)amino-1-acetyl-1-cyclohexenylglyoxime, and [L³H₂], N-(4-methoxyphenyl)amino-1-acetyl-1-cyclohexenylglyoxime were synthesized from 1-acetyl-1-cyclohexeneglyoxime and the corresponding substituted aromatic amines. Metal complexes of these ligands were also synthesized with Ni(II), Cu(II), and Co(II) salts. These new compounds (ligands and complexes) were characterized with FT–IR, magnetic susceptibility measurement, molar conductivity measurements, mass spectrometry measurements, thermal methods (e.g. thermal gravimetric analysis), ¹H NMR (Nuclear Magnetic Resonance) and ¹³C NMR spectral data and elemental analyses.     

Thermal behaviour of hydrated copper(II) complexes

Dehydration steps of aquacopper(II) complexes with homogeneous and heterogeneous coordination sphere are investigated from the view point of structural changes taking place under their heating to the decomposition temperature and during the dehydration. The role of loosening of intra-and intermolecular hydrogen bonds in the decomposition reaction for the structure changes of the remainder, the structural presumptions of the reactants for lower hydrates formation are discussed. Activation parameters of dehydration were found to be the lower, the smaller are the structure differences between the reactants and products. They do not reflect the bond length central atomvolatile ligand, much more the overall structure differences between the starting and resulting compounds. From all data on crystal and molecular structures of dehydrated compounds is the reaction pathway best indicated by anisotropic temperature parameters of donor atoms corrected for the thermal movement of the central atom: the higher these values in the bond direction are, the lower the values of activation energies of dehydration are.     

Syntheses and characterization of nickel(II), zinc(II) and palladium(II) complexes derived from three pyrazole-based polydentate ligands

Two pyrazole-based polydentate ligands, 1,3-bis(5-methyl-3-phenylpyrazol-1-yl)-propan-2-ol (Hmppzpo) and 1,3-bis(5-methyl-3-p-isopropylphenylpyrazol-1-yl)-propan-2-ol (Hmcpzpo), have been synthesized. A third ligand, 1,3-bis(3,5-dimethylpyrazol-1-yl)-propan-2-ol (Hdmpzpo), has been synthetically modified. Seven new M(II) coordination compounds of general formula M₂L₂X₂ (M?=?Zn, Ni; X?=?NO₃ or ClO₄; L?=?dmpzpo, mppzpo or mcpzpo) or MLX (M?=?Pd; L?=?dmpzpo; X?=?Cl) were synthesized and structurally characterized by elemental analysis and FT-IR analysis. The crystal structures of [Zn₂(μ-dmpzpo-O,N,N′)₂(NO₃)₂]?·?2H₂O (1?·?2H₂O), [Ni₂(μ-dmpzpo-O,N,N′)₂(CH₃CN)₂](ClO₄)₂ (2) and Pd(μ-dmpzpo-N,N′)Cl₂ (4) were determined by single-crystal X-ray crystallography. The crystal structures show that complexes 1?·?2H₂O and 2 are center-symmetric dinuclear compounds, with two metal ions bridged by two alkoxo groups and each metal ion with a distorted square-pyramidal environment. The palladium complex, 4, displayed square-planar coordination geometry around the Pd(II) ion with trans arrangement.     

Studies on mononuclear chelates derived from substituted Schiff-base ligands (part 6): synthesis and characterization of a new 3-ethoxysalicyliden- p -aminoacetophenoneoxime and its complexes with cobalt(II), nickel(II), copper(II) and zinc(II)

Schiff-base complexes of cobalt(II), nickel(II), copper(II) and, zinc(II) with 3-ethoxysalicyliden-p-aminoacetophenoneoxime (HL) were prepared and characterized on the basis of elemental analyses, IR, ¹H- and ¹³C-NMR, electronic spectra, magnetic susceptibility measurements, molar conductivity and thermogravimetric analyses (TGA). A tetrahedral geometry has been assigned to the complexes.     

Synthesis,characterization and antimicrobial activity of 5‐(arylazo)salicylaldimines and their copper(II) complexes

A new series of twelve bidentate Schiff's base ligands (HL^1–12) was synthesized via condensation of 5‐(arylazo)salicylaldehydes with aromatic amines. When the new salicylaldimine derivatives were reacted with copper(II) chloride, the neutral complexes Cu(L^1–12)₂ were obtained. The structure of the copper complexes was established from microanalyses, IR and UV spectra and thermal analyses. The results suggested that the ligands were coordinated to the metal ion in a bidentate manner with ON donor sites of the deprotonated phenolic‐OH and azomethine‐N. The composition of the complexes can be represented as CuL₂. Evaluation of antimicrobial activity for the synthesized compounds was carried out to probe their activity. The compounds were found to have weak antimicrobial activity.     

Cu(II) and Ni(II)‐1,10‐phenanthroline‐ 5,6‐dione‐amino acid ternary complexes exhibiting pH‐sensitive redox properties

Syntheses, and electrochemical properties of two novel complexes, [Cu(phendio)(L ‐Phe)(H₂O)](ClO₄) ·H₂O (1) and [Ni(phendio)(Gly)(H₂O)](ClO₄)·H₂O (2) (where phendio = 1,10‐phenanthroline‐5,6‐dione, L ‐Phe = L ‐phenylalanine, Gly = glycine), are reported. Single‐crystal X‐ray diffraction results of (1) suggest that this complex structure belongs to the orthorhombic crystal system. The electrochemical properties of free phendio and these complexes in phosphate buffer solutions in a pH range between 2 and 9 have been investigated using cyclic voltammetry. The redox potential of these compounds is strongly dependent on the proton concentration in the range of ? 0.3–0.4 V vs SCE (saturated calomel reference electrode). Phendiol reacts by the reduction of the quinone species to the semiquinone anion followed by reduction to the fully reduced dianion. At pH lower than 4 and higher than 4, reduction of phendio proceeds via 2e^?/3H⁺ and 2e^?/2H⁺ processes. For complexes (1) and (2), being modulated by the coordinated amino acid, the reduction of the phendio ligand proceeds via 2e^?/2H⁺ and 2e^?/H⁺ processes, respectively. Copyright © 2006 John Wiley & Sons, Ltd.     

Synthesis, crystal structure, spectroscopic and photoluminescence studies of manganese(II), cobalt(II), cadmium(II), zinc(II) and copper(II) complexes with a pyrazole derived Schiff base ligand

Varying coordination modes of the Schiff base ligand H₂L [5-methyl-1-H-pyrazole-3-carboxylic acid (1-pyridin-2-yl-ethylidene)-hydrazide] towards different metal centers are reported with the syntheses and characterization of four mononuclear Mn(II), Co(II), Cd(II) and Zn(II) complexes, [Mn(H₂L)(H₂O)₂](ClO₄)₂(MeOH) (1), [Co(H₂L)(NCS)₂] (2), [Cd(H₂L)(H₂O)₂](ClO₄)₂ (3) and [Zn(H₂L)(H₂O)₂](ClO₄)₂ (4), and a binuclear Cu(II) complex, [Cu₂(L)₂](ClO₄)₂ (5). In the complexes 1-4 the neutral ligand serves as a 3N,2O donor where the pyridine ring N, two azomethine N and two carbohydrazine oxygen atoms are coordinatively active, leaving the pyrazole-N atoms inactive. In the case of complex 5, each ligand molecule behaves as a 4N,O donor utilizing the pyridine N, one azomethine N, the nitrogen atom proximal to the azomethine of the remaining pendant arm and one pyrazole-N atom to one metal center and the carbohydrazide oxygen atom to the second metal center. The complexes 1-4 are pentagonal bipyramidal in geometry. In each case, the ligand molecule spans the equatorial plane while the apical positions are occupied by water molecules in 1, 3 and 4 and two N bonded thiocyanate ions in 2. In complex 5, the two Cu(II) centers have almost square pyramidal geometry (τ = 0.05 for Cu1 and 0.013 for Cu2). Four N atoms from a ligand molecule form the basal plane and the carbohydrazide oxygen atom of a second ligand molecule sits in the apex of the square pyramid. All the complexes have been X-ray crystallographically characterized. The Zn(II) and Cd(II) complexes show considerable fluorescence emission while the remaining complexes and the ligand molecule are fluorescent silent.     

Synthesis and spectroscopic studies of copper(II) and nickel(II) complexes containing hydrazonic ligands and heterocyclic coligand

Two types of copper(II) and nickel(II) complexes derived from benzophenone anthranoylhydrazone (L1), 2-acetonaftanone anthranoylhydrazone (L2), 4-phenylacetonaftonone anthranoylhydrazone (L3), benzophenone salicyoylhydrazone (L4), 2-acetonaftanon salicyoylhydrazone (L5), 4-phenylacetonaftanon salicyoylhydrazone (L6) and bidentate heterocyclic base [1,10-phenanthroline (phen)] with general stoichiometry [ML2] and [ML(phen)]Cl have been synthesized and characterized by elemental analysis, infrared spectra, UV-vis electronic absorption spectra and magnetic susceptibility measurements. The effect of varying pH and solvent on the absorption behavior of both ligands and complexes have been investigated. According to the IR spectra, the ligands act as monobasic bidentate and coordination takes place in the enol tautomeric form.     

Oxovanadium(IV), copper(II) or cobalt(II) acetylacetone complexes immobilized on amino‐functionalized CMK‐3 for the aerobic epoxidation of styrene

Oxovanadium(IV), copper(II) and cobalt(II) acetylacetone complexes have been grafted onto amino‐modified CMK‐3‐O (VO‐NH₂‐CMK‐3, Cu‐NH₂‐CMK‐3 and Co‐NH₂‐CMK‐3,respectively) and the materials thus prepared were used as heterogeneous catalysts for the aerobic oxidation of styrene. X‐ray diffraction, nitrogen adsorption–desorption and transmission electron microscopy measurements confirmed the structural integrity of the mesoporous hosts, and spectroscopic characterization techniques (Fourier transform infrared, X‐ray photoelectron, Raman) and thermogravimetry confirmed the ligands and the successful anchoring of the acetylacetone complexes to the modified mesoporous support. VO‐NH₂‐CMK‐3 displayed a relatively good catalytic performance with 94.6% of styrene conversion using air as oxidant, while Cu‐NH₂‐CMK‐3 gave 99.6% of styrene conversion using tert‐butyl hydroperoxide as oxidant. Copyright © 2015 John Wiley & Sons, Ltd.     

Copper(II) complexes of two TEMPO-functionalized polypyridyl ligands: structure and catalytic activity in alcohol oxidation

The reaction of copper(II) salts with Bpy-TEMPO and Tpy-TEMPO (Bpy-TEMPO = [2,2′]Bipyridinyl-5,5′-dicarboxylic acid bis-[(2,2,6,6-tetramethyl-1-oxy-piperidin-4-yl)-amide]; Tpy-TEMPO = 2,2,6,6-tetramethyl-4-(2,2′:6′,2″-terpyridin-4′-yloxy)piperidin-1-oxyl) gave dinuclear Bpy-TEMPO-Cu₂ (1) and mononuclear Tpy-TEMPO-Cu (2), respectively. The Cu(II) complexes were characterized by single crystal X-ray analysis. In 1, Cu(II) has a distorted square pyramidal coordination geometry, with a bridging chloride as the axial ligand. The Cu(II) core in 2 also exhibited a distorted square pyramidal coordination geometry, with one chloride as an axial ligand. Weak interactions such as π-interactions and hydrogen bonds are observed in both complexes. When applied as catalysts for the oxidation of benzyl alcohol to benzaldehyde in air, 1 exhibited higher activity than 2 for reactions in o-xylene at 60°C with DBU as a base. High yield (67%) of benzaldehyde was observed when using 1 as a catalyst in a solution of o-xylene with DBU at 60°C.     

Kinetic features of the adsorption of water vapor by copper and nickel ammine complexes with polyoxometallate anions

The rate of adsorption of water vapor by compounds obtained from cationic copper(II) and nickel(II) ammine complexes and polyoxometallate anions may be described by the linear driving force mass transfer model as one or two parallel processes. The differences observed were attributed to differences in the crystal structure of the adsorbents. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 43, No. 2, pp. 112–117, March–April, 2007.