Cobalt(II), nickel(II), copper(II) and zinc(II) complexes with an open-chain pentadentate nitrogen ligand

The open-chain, potentially, pentadentate, ligan 1,11-bis(dimethylamino)-3,6,9-trimethyl-3,6,9,-triazaundecane (Me₇tetren) forms a series of metal complexes having the general formula [M(Me₇tetren)]Y₂ (Y = 1, M = Co, Ni; Y = ClO₄, M = Co, Ni, Cu, Zn). On the basis of their physical properties, it is suggested that all these compounds contains isostructural five-coordinate [M(Me₇tetren)]²⁺ cations, the ligand acting as pentadentate. These complexes react in solution with thiocyanate ion to give mono- and, with exception of copper(II), di-thiocyanato five- and six-co-ordinate derivatives. Mono-thiocyanato derivatives of cobalt(II), nickel(II) and zinc(II) have been isolated as tetraphenylborate salts. Cobalt(II) and nickel (II) di-thiocyanato derivatives have been also isolated. Results are discussed in terms of the steric requirements of the ligand and electronic properties of the metal ions.     

Synthesis, characterization, and antibacterial activity of novel Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) complexes with vitamin K3-thiosemicarbazone

Vitamin K3-thiosemicarbazone (C12H11N3NaO4S2 x 5H2O, abbreviated as VT), a new Schiff base derivative, has been synthesized. Its crystal structure, determined by X-ray diffraction, is triclinic, space group P1. We have also prepared five novel complexes of VT with transition metals: [M(VT)(2)2H2O] x nH2O, (n = 1 and 2 for M = Cu(II) and Zn(II), respectively) and [M'(HVT)2Cl2] x mH2O, (m = 4, 5, and 7 for M' = Co(II), Mn(II), and Ni(II), respectively). These compounds were characterized by IR and UV-Vis spectroscopy, molar conductivity, thermal analyses, complexometric titration, and elemental analysis. In all the complexes, the VT ligand coordinates through sulfur and oxygen atoms, and the geometry around metal atom is best described as octahedral. In vitro tests of antibacterial activity showed that VT and its complexes with Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) all had strong inhibitory actions against G(+) Staphylococcus aureus, G(+) Hay bacillus, and G(-) Escherichia coli.     

Complexes of a macrocyclic ligand having both mono- and binucleating capability: binuclear Mn(II), Fe(II), Co(II), Ni(II), Zn(II) complexes

Bi-nuclear complexes of 28- atom membered macrocycles derived from 2,6-diacetyl pyridine and the amines 3,3′-diamino dipropylamine or 3,3′-diamino-N-methyl dipropylamine have been prepared by template synthesis on Ag⁺ or Pb²⁺. Template synthesis can also be accomplished, in the case of 3,3′-diamino dipropylamine, but not its N-methyl derivative, on Gp(II) metal ions, with accompanying rearrangement of the macrocycle. All the complexes produced by template synthesis can be transmetallated with the first transition series metal ions M = Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II) to give binuclear and in some cases, mononuclear, derivatives. The binuclear complexes show no evidence of magnetic exchange interaction from magnetic susceptibility measurements in the range 93-300 K. The cyclovoltammetric behaviour of mono- and bi-nuclear Fe(II) complexes is compared.     

Ternary complexes metal [Co(II), Ni(II), Cu(II) and Zn(II)]--ortho-iodohippurate (I-hip)--acyclovir. X-ray characterization of isostructural [(Co, Ni or Zn)(I-hip)(2)(ACV)(H(2)O)(3)] with stacking as a recognition factor

Four ternary metal--ortho-iodohippurate (I-hip)--acyclovir (ACV) complexes, [M(I-hip)(2)(ACV)(H(2)O)(3)] where M is Co(II) (1), Ni(II) (2), Cu (3) and Zn(II) have been obtained by reaction between the corresponding binary complexes M(II)(I-hip)(2)xnH(2)O and ACV. Three ternary complexes (M=Co, Ni and Zn) and the corresponding Zn(II)--ortho-iodohippurate binary derivative have been structurally characterized by X-ray diffraction: The studies show these three ternary complexes are isostructural and present, in solid state, an interesting stacking between the nucleobase and the aryl ring of the hippurate moiety, which probably promotes the formation of ternary complexes. Moreover, the two different ligands interact between them by means of ancillary hydrogen bonds with water molecules coordinated to the metal ion. It must be mentioned that these two recognition factors, hydrogen bonds plus stacking, could explain the reason for the isostructurality of these ternary derivatives with so different three metal ions, with diverses trends in coordination numbers and geometries. In solid state, there are two enantiomeric molecules that are related by an inversion center as the crystal-building unit (as a translational motif) for the ternary complexes.     

Complexes of Co(II), Ni(II), Cu(II) and Zn(II) with 3′AMP and 2′AMP

Derivatives of Co(II), Ni(II), Cu(II) and Zn(II) with 3′AMP and 2′AMP were synthesized and characterized by IR UV-Vis and fluorescence spectroscopy. There seems to be bonding of the metal ion to the base in all cases. The activation test, using the complexes as allosteric labels, was carried out with rabbit muscle glycogen phosphorylase b, but the enzyme was not activated, confirming that the phosphate group must necessarily be bonded to position 5′ of the ribose in order to activate this enzyme.     

Synthesis, physico-chemical characterization and antimicrobial activity of cobalt(II), nickel(II), copper(II), zinc(II) and cadmium(II) complexes with some acyldihydrazones

Complexes of the type [M(bssdh)]Cl and [M(dspdh)]Cl, where M = Co(II), Ni(II), Cu(II), Zn(II) and Cd(II); Hbssdh = benzil salicylaldehyde succinic acid dihydrazone, Hdspdh = diacetyl salicylaldehyde phthalic acid dihydrazone have been synthesized and characterized with the help of elemental analyses, electrical conductance, magnetic susceptibility measurements, electronic, ESR and IR spectra and X-ray diffraction studies. Magnetic moment values and electronic spectral transitions indicate a spin free octahedral structure for Co(II), Ni(II) and Cu(II) complexes. IR spectral studies suggest that both the ligands behave as monobasic hexadentate ligands coordinating through three > C = O, two > C = N- and a phenolate group to the metal. ESR spectra of Cu(II) complexes are axial type and suggest d(x(2)-y(2)) as the ground state. X-ray powder diffraction parameters for [Co(bssdh)]Cl and [Co(dspdh)]Cl complexes correspond to an orthorhombic crystal lattice. The ligands as well as their metal complexes show a significant antifungal and antibacterial activity against various fungi and bacteria. The metal complexes are more active than the parent ligands.     

Stereochemistry and fungitoxicity of complexes of p-anisaldehydethiosemicarbazone with Mn(II), Fe(II), Co(II) and Ni(II)

The complexes of p-Anisaldehydethiosemicarbazone (PAT) with Mn(II), Fe(II), Co(II) and Ni(II) have been isolated and characterised on the basis of elemental analyses, molar conductance, magnetic moment and spectral studies. Fungicidal activity has been evaluated against Alternaria (Sp.), Paecilomyces (Sp.) and Pestalotia (Sp.).     

Synthesis, characterization and antitumor studies of Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) complexes of N-salicyloyl-N'-o-hydroxythiobenzhydrazide

A new ligand N-salicyloyl-N'-o-hydroxythiobenzhydrazide (H2Sotbh) forms complexes [Mn(HSotbh)2], [Fe(Sotbh-H)(H2O)2], [M(Sotbh)] [M=Co(II), Cu(II) and Zn(II)] and [Ni(Sotbh)(H(2)O)2], which were characterized by various physico-chemical techniques. M?ssbauer spectrum of [Fe(Sotbh-H)(H2O)2] reveals the quantum admixture of 5/2 and 3/2 spin-states. Mn(II), Cu(II) and Ni(II) complexes were observed to inhibit the growth of tumor in vitro, whereas, Fe(III), Co(II), Zn(II) complexes did not. In vivo administration of Mn(II), Cu(II) and Ni(II) resulted in prolongation of survival of tumor bearing mice. Tumor bearing mice administered with Mn(II), Cu(II) and Ni(II) complexes showed reversal of tumor growth associated induction of apoptosis in lymphocytes. The paper discusses the possible mechanisms and therapeutic implication of the H2Sotbh and its metal complexes in tumor regression and tumor growth associated immunosuppression.     

Synthesis,physico-chemical characterization and antimicrobial activity of cobalt(II), nickel(II), copper(II), zinc(II) and cadmium(II) complexes with some acyldihydrazones

Complexes of the type [M(bssdh)]Cl and [M(dspdh)]Cl, where M = Co(II), Ni(II), Cu(II), Zn(II) and Cd(II); Hbssdh = benzil salicylaldehyde succinic acid dihydrazone, Hdspdh = diacetyl salicylaldehyde phthalic acid dihydrazone have been synthesized and characterized with the help of elemental analyses, electrical conductance, magnetic susceptibility measurements, electronic, ESR and IR spectra and X–ray diffraction studies. Magnetic moment values and electronic spectral transitions indicate a spin free octahedral structure for Co(II), Ni(II) and Cu(II) complexes. IR spectral studies suggest that both the ligands behave as monobasic hexadentate ligands coordinating through three > C = O, two > C = N– and a phenolate group to the metal. ESR spectra of Cu(II) complexes are axial type and suggest as the ground state. X–ray powder diffraction parameters for [Co(bssdh)]Cl and [Co(dspdh)]Cl complexes correspond to an orthorhombic crystal lattice. The ligands as well as their metal complexes show a significant antifungal and antibacterial activity against various fungi and bacteria. The metal complexes are more active than the parent ligands.     

N-benzoyl-N'-alkylthioureas and their complexes with Ni(II), Co(III) and Pt(II) - crystal structure of 3-benzoyl-1-butyl-1-methyl-thiourea: activity against fungi and yeast

The thiourea derivatives of N-butylmethylamine (3-benzoyl-1-butyl-1-methyl-thiourea) (1), N-ethylisopropylamine (3-benzoyl-1-ethyl-1-isopropyl-thiourea) (2) and the corresponding complexes of 1 and 2 with Ni(II), Co(III) and Pt(II) have been synthesized. The compounds obtained were characterized by elemental analysis, spectroscopic methods (FT-IR, UV-Vis and NMR) and mass spectrometry. Compound 1, crystallized in the triclinic space group. The antifungal activities of compounds 1 and 2 and their corresponding complexes against the fungus Penicillium digitatum and against the yeast Saccharomyces cerevisiae were investigated. In general, fungal growth inhibition was higher with compound 1 and its complexes than with compound 2, except for the Co(III) complex of 2.     

Antibacterial cobalt(II), nickel(II) and zinc(II) complexes of nicotinic acid-derived Schiff-bases

Nicotinic acid derived Schiff bases and their transition metal [cobalt(II), nickel(II) and zinc(II)] complexes have been prepared and characterized by physical, spectral and analytical data. The Schiff bases act as deprotonated tridentate ligands for the complexation of the above mentioned metal ions. These complexes, possessing the general formula [M(L)2] [where M = Co(II), Ni(II) and Zn(II) and L = HL1-HL4] showed an octahedral geometry of the metal ions. For determining the effect of metal ions upon chelation, the Schiff bases and their complexes have been screened for antibacterial activity against several pathogenic strains of Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. The new metal derivatives reported here were more bactericidal against one or more bacterial species as compared to the uncomplexed Schiff bases.     

Homo and hetero dioxygen complexes of Co(II), Cu(II), Ni(II) and Pb(II) with the ligand 3,7,11,19,23,27-hexaaza-33,34-dihydroxy-15,31-dimethyltricyclotetratriaconta-1(32),13,15,17(34),29(33),30-hexaene

In this paper the oxygenation of HDTHCo homo and heterodinuclear complexes with Cu(II), Ni(II) and Pb(II) in aqueous solution by control of the stoichiometry of metal ions and HDTH as well as p[H] of solution was investigated (HDTH is a dinucleating 28-membered hexaazadiphenol macrocyclic ligand, 3,7,11,19,23,27-hexaaza-33,34-dihydroxy-15,31-dimethyl-tricyclo-tetratriaconta-1(32),13,15,17(34),29(33),30-hexaene). The pH potentiometric method was utilized successfully to determine oxygenation constants and to determine the distribution of species present in the solution as a function of p[H]. Spectrophotometry was used to investigate the oxygenation process of the homo and heterodinuclear complexes. The X-ray crystal structure of homodinuclear complexes of Ni(II) is also reported. These studies suggested autooxidation takes place during the oxygenation of homo and heterodinuclear Co(II) complexes of the macrocyclic ligand. The neighboring effect increases in the order Ni(II)<Cu(II)<Pb(II)<Co(II). Pb(II) stimulates the neighboring Co(II) to accept dioxygen in its sixth vacant position. Ni(II) is not helpful to Co(II) in its oxygenation.     

Synthesis, spectral characterization and in vitro biological studies of Co(II), Ni(II) and Cu(II) complexes with 1,2,4-triazole Schiff bases

A series of metal complexes of cobalt(II), nickel(II) and copper(II) have been synthesized with newly derived biologically active ligands. These ligands were synthesized by the condensation of 3-substituted-4-amino-5-hydrazino-1,2,4-triazole and 8-formyl-7-hydroxy-4-methylcoumarin. The probable structure of the complexes has been proposed on the basis of elemental analyses and spectral (IR, Uv-Vis, magnetic, ESR, FAB-mass and thermal studies) data. Electro chemical study of the complexes is also reported. All these complexes are non-electrolytes in DMF and DMSO. All the ligands and their Co(II), Ni(II) and Cu(II) complexes were screened for their antibacterial (Escherichia coli, Staphylococcus aureus, Staphylococcus pyogenes and Pseudomonas aeruginosa) and antifungal (Aspergillus niger, Aspergillus flavus and cladosporium) activities by MIC method. The brine shrimp bioassay was also carried out to study their in vitro cytotoxic properties.     

Interaction of adenosine 5'-triphosphate with metal ions X-ray structure of ternary complexes containing Mg(II), Ca(II), Mn(II), Co(II), ATP and 2,2'-dipyridylamine

The X-ray structures of the isomorphous Mg2+, Ca2+, Mn2+ and Co2+ complexes of ATP have been determined. The metal ions are wrapped in hexa-coordination by the alpha, beta and gamma phosphate groups of two ATP molecules thus blocking the interaction of the metal ions with the adenine base. A second metal ion which is fully hydrated, M(H2O)2+(6), is engaged in a strong hydrogen bond with the gamma phosphate group of ATP and suggests a possible step in facilitating the cleavage between the beta and gamma phosphates in phosphoryl transfer reactions.     

Interaction of water-soluble Cu(II), Ni(II), and Co(III) porphyrins with polynucleotides

The interaction of the Cu(II), Ni(II) and Co(III) complexes of the following six water-soluble cationic porphyrins with calf thymus DNA, poly(dG-dC)2 and poly(dA-dT)2 was studied by UV-visible and resonance Raman spectroscopy: tetrakis(2-N-) and (3-N-methylpyridyl) porphyrin (1, 2); monophenyl-tris(4-N-methylpyridyl)porphyrin (4); cis- and trans-diphenyl-bis (4-N-methylpyridyl)porphyrin (5, 6). The binding to nucleic acids was compared with that of tetrakis(4-N-methylpyridyl)porphyrin (3). If the N(+)-CH3 group is moved from the para (3) to the meta position (2), binding of the free porphyrin as well as that of the metal complexes is only gradually modified; thus, the square-planar Cu- and Ni-2 are intercalated at the G-C site whereas Co-2 is groove-bound at A-T. Additionally, Ni-2 is probably also intercalated at the A-T site. When the N(+)-CH3 group is located at ortho position (1), the high rotation barrier of the 2-N-methylpyridyl group prevents intercalation of Cu- and Ni-1, resulting in weak outside binding. At ionic strength mu = 0.2, there is no evidence of significant interaction of Co-1 with any of the polynucleotides. When the charged N-methylpyridyl groups in 3 are subsequently replaced by phenyl groups (4, 5/6), the tendency of the Cu(II) and Ni(II) complexes to bind to the outside of the helix or to intercalate only partially increases at the expense of full intercalation. The coulombic attraction remains strong, no significant differences can be detected between 3, 4, 5, and 6. Ni-4 binds to poly(dA-dT)2 in the same complicated manner as Ni-3. The outside-binding in Co-4, -5 and -6 differs slightly from that in Co-2 and Co-3.     

Synthesis,spectral characterization and in vitro biological studies of Co(II), Ni(II) and Cu(II) complexes with 1,2,4-triazole Schiff bases

A series of metal complexes of cobalt(II), nickel(II) and copper(II) have been synthesized with newly derived biologically active ligands. These ligands were synthesized by the condensation of 3-substituted-4-amino-5-hydrazino-1,2,4-triazole and 8-formyl-7-hydroxy-4-methylcoumarin. The probable structure of the complexes has been proposed on the basis of elemental analyses and spectral (IR, Uv-Vis, magnetic, ESR, FAB-mass and thermal studies) data. Electro chemical study of the complexes is also reported. All these complexes are non-electrolytes in DMF and DMSO. All the ligands and their Co(II), Ni(II) and Cu(II) complexes were screened for their antibacterial (Escherichia coli, Staphylococcus aureus, Staphylococcus pyogenes and Pseudomonas aeruginosa) and antifungal (Aspergillus niger, Aspergillus flavus and cladosporium) activities by MIC method. The brine shrimp bioassay was also carried out to study their in vitro cytotoxic properties.     

A family of polyamino phenolic macrocyclic ligands. Acid-base and coordination properties towards Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Pb(II) ions

The acid-base and coordination properties towards Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Pb(II) of four polyamino-phenol macrocycles 15-hydroxy-3,6,9-triazabicyclo[9.3.1]pentadeca-11,13,1¹⁵-triene L1, 18-hydroxy-3,6,9,12-tetraazabicyclo[12.3.1]octadeca-14,16,1¹⁸-triene L2, 21-hydroxy-3,6,9,12,15-pentaazabicyclo[15.3.1]enaicosa-17,19,1²¹-triene L3 and 24-hydroxy-3,6,9,12,15,18-hexaazabicyclo[18.3.1]tetraicosa-20,22,1²⁴-triene L4 are reported. The protonation and stability constants were determined by means of potentiometric measurements in 0.15 mol dm⁻³ NMe₄Cl aqueous solution at 298.1 K. L1 forms highly unsaturated Co(II), Cu(II), Zn(II) and Cd(II) mononuclear complexes that are prone to give dimeric dinuclear species with [(MH₋₁L1)₂]²⁺ stoichiometry, in solution. L2 forms stable Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Pb(II) mononuclear complexes that can coordinate external species as OH⁻ anion, giving hydroxylated complexes at alkaline pH. L3 forms stable Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Pb(II) mononuclear complexes and Co(II), Ni(II), Cu(II) and Zn(II) dinuclear [M₂H₋₁L3]³⁺ species. L4 forms stable mono- and dinuclear Co(II), Cu(II), Zn(II) and Cd(II) complexes, but only mononuclear species with Pb(II). The effect of macrocyclic size is considered in the discussion of results.     

Synthesis, physico-chemical studies of manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) complexes with some p-substituted acetophenone benzoylhydrazones and their antimicrobial activity

Complexes of the type [M(pabh)(H2O)Cl], [M(pcbh)(H2O)Cl] and [M(Hpabh)(H2O)2 (SO4)] where, M = Mn(II), Co(II), Ni(II), Cu(II) and Zn(II); Hpabh = p-amino acetophenone benzoyl hydrazone and Hpcbh = p-chloro acetophenone benzoyl hydrazone have been synthesized and characterized with the help of elemental analyses, electrical conductance, magnetic susceptibility measurements, electronic, ESR and IR spectra, thermal (TGA & DTA) and X-ray diffraction studies. Co(II), Ni(II) and Cu(II) chloride complexes are square planar, whereas their sulfate complexes have spin-free octahedral geometry. ESR spectra of Cu(II) complexes with Hpabh are axial and suggest d(x(2)-y(2) as the ground state. The ligand is bidentate bonding through > C = N--and deprotonated enolate group in all the chloro complexes, whereas, >C = N and >C = O groups in all the sulfato complexes. Thermal studies (TGA & DTA) on [Cu(Hpabh)(H2O)2(SO4)] indicate a multistep decomposition pattern, which are both exothermic and endothermic in nature. X-ray powder diffraction parameters for [Co(pabh)(H2O)Cl] and [Ni(Hpabh)(H2O)2(SO4)] correspond to tetragonal and orthorhombic crystal lattices, respectively. The ligands as well as their complexes show a significant antifungal and antibacterial activity. The metal complexes are more active than the ligand.     

Biologically important coordination compounds of 4-acetyl-2-(acetylamino)-5-dimethyl-δ2-1,3,4-thiadiazole with manganese(II), iron(II), cobalt(II) and nickel(II)

The complexes of 4-Acetyl-2-(acetylamino)-5- dimethyl-δ²-1,3,4-thiadiazole (AAT) with Mn(II), Fe(II), Co(Il) and Ni(II) have been prepared and characterized on the basis of elemental analyses, molar conductance, magnetic moments, electronic and infrared spectral studies. The most probable structures of the complexes have been proposed on the basis of their physicochemical properties. The fungitoxicity of AAT and its complexes has been evaluated on pathogenic fungi.     

Synthesis, characterization and biological activity evaluation of Pt(II), Pd(II), Co(III) and Ni(II) complexes with N-heteroaromatic selenosemicarbazones

Five new complexes of Pt(II), Pd(II), Co(III) and Ni(II) with 2-pyridine(quinoline)carboxaldehyde selenosemicarbazones were synthesized and characterized. Crystal structures of Pt(II) complex with the pyridine derivative and Co(III) complex with the quinoline derivative were determined. In all complexes the ligands were coordinated through N₂Se donor atom set forming either square-planar (Pt, Pd) or octahedral (Co, Ni) geometry. All complexes showed biological activity.