Copper(II)–8-mercaptoquinoline,copper(II)–5,8-dimercaptoquinoline and copper(II)–5-thiomethyl-8-mercaptoquinoline complexing in a copper(II)hexacyanoferrate(II) gelatin-immobilized matrix

Novel complexing processes in the Cu^II–8-mercaptoquinoline, Cu^II–5,8-dimercaptoquinoline and Cu^II–5-thiomethyl-8-mercaptoquinoline systems proceeding in the copper(II)hexacyanoferrate(II) gelatin-immobilized matrix in contact with aqueous solutions of the ligands indicated, have been studied. Under the conditions specified for complexing in the Cu^II–8-mercaptoquinoline system, only a monomeric water-insoluble coordination compound was formed. In the Cu^II–5,8-dimercaptoquinoline system, three coordination compounds were formed and, in the Cu^II–5-thiomethyl-8-mercaptoquinoline system, two such compounds were formed. Conversely, complexing in solution or solid phase results in the formation only coordination compounds in each of the system studied.     

Copper(II)–1,2-bis(thiocarbamoyl)hydrazine and copper(II)–(1-carbamoyl-2-thiocarbamoyl)hydrazine complexing in copper(II)hexacyanoferrate(II) gelatin-immobilized matrix systems

The complex formation that occurs in gelatin-immobilized copper(II)hexacyanoferrate(II) matrices upon contact with aqueous alkaline (pH 12.0) solutions of 1,2-bis(thiocarbamoyl)hydrazine, H₂NC(S)NHNHC(S)NH₂ and 1-carbamoyl-2-(thiocarbamoyl)hydrazine, H₂NC(O)NHNHC(S)NH₂ has been studied. The reaction of each of these ligands with copper(II) is preceded by the destruction of copper(II)hexacyanoferrate(II) in an alkaline medium to form a polymeric copper(II) hydroxide, which is involved in the subsequent copper(II)–ligand complex formation. In both Cu^II–N ligand systems, two complex compounds are formed; the water-insoluble Cu₂B₂(H₂O)₂ dimer and a water-soluble product of tentative composition [CuB(HB)]^– (H₂B=ligand).     

Soft template synthesis in the cobalt(III)–1,2-diaminoethane-1,2-dithione–propanone triple system on a K[CoFe(CN)<Subscript>6</Subscript>]-gelatin-immobilized matrix

Complexation of Co^III, in the form of K[CoFe(CN)₆]-gelatin-immobilized matrix, in contact with aqueous-alkaline solutions (pH ∼ 12) containing 1,2-diaminoethane-1,2-dithione and propanone, has been studied. Template synthesis leading to a chelate Co^III coordination compound with a tetradentate N,N,S,S-donor ligand identified as 4,4,6-trimethyl-1,9-diamino-1,9-dimercapto-3,7-diazanon-3-en-2,8-dithione and hydroxy co-ligand occurs under these specific conditions. 1,2-Diaminoethane-1,2-dithione and propanone are the ligand synthons in this process.     

Ferromagnetic copper(II)–copper(II) interaction in a single chlorido and dicyanamido bridged mixed–valence copper(I/II) 2-D polymer generated by in situ partial reduction of copper(II)

A mixed-valence 2-D Cu(I/II) complex, [{Cu(II)(dmen)(μ-Cl)(μ_1,5-dca)}{Cu(I)(μ_1,5-dca)}]_n (1) (dmen = N,N-dimethylethylenediamine, dca = dicyanamide = [N(CN)₂]^?), has been synthesized by in situ partial reduction of Cu(II) to Cu(I) using benzoin (2-hydroxy-1,2-di(phenyl)ethanone) as reductant. Complex 1 was characterized by spectroscopic techniques, single crystal X-ray diffraction, and low temperature magnetic measurements. Structural investigation reveals that 1 represents a mixed-valence 2-D coordination polymer formed by parallel 1-D [Cu(II)(dmen)(Cl)Cu(I)(μ_1,5-dca)₂]_n chains running along the b axis, where chloride bridges Cu(II) ions of adjacent polymers through long connections (2.8401(1) Å) to form a 2-D network. The metal centers have two different geometrical environments (distorted square pyramidal and distorted trigonal planar geometries for Cu(II) and Cu(I), respectively). The Cu(II) ions in [Cu(II)(dmen)(μ-Cl)(dca)]_n are interconnected through single chloride bridges while within the [Cu(I)(μ_1,5-dca)]_n units, the dca connects adjacent Cu(I) ions through μ_1,5-dca bridges. Magnetic susceptibility measurements reveal weak ferromagnetic interactions (J = +0.3 cm^?1) within the chlorido-bridged Cu(II) regular chain present in 1. Simultaneous presence of μ_1,5-dca and single chlorido bridges with ferromagnetic coupling is believed to be unique in mixed-valence Cu(I)/Cu(II) complexes.     

Interconversion of copper(II) to copper(I): synthesis,characterization of copper(II) and copper(I) 2,2′-biquinoline complexes and their microbiological activity

The complexes [Cu(biq)₂]Cl₂ and [Cu(biq)₂]BF₄·biq (biq?=?2,2′-biquinoline) have been prepared and characterized. The interconversion to copper(I) complex [Cu(biq)₂]BF₄·biq, from [Cu(biq)₂]Cl₂ has been established. The new complexes have been characterized by elemental analysis, conductivity and magnetic measurements, IR, UV-vis and ¹H- and ¹³C-NMR spectroscopy. The X-ray analysis of the complex [Cu(biq)₂]BF₄·biq supports the assumption of the interconversion of copper(II) to copper(I) in this case. The crystal structure shows that geometry around the metal is severely distorted from T_d, and displays many supramolecular motifs incorporating both hydrophobic (aryl···aryl) and hydrophilic (C–H···F) intermolecular interactions. The microbiological activity of the complexes against bacteria and fungi was found to be high against Candida albicans, and slight to moderate against bacteria. The antimicrobial activity of [Cu(biq)₂]BF₄·biq was slightly better than that observed for [Cu(biq)₂]Cl₂ against both bacteria and fungi.     

Low-temperaturic template synthesis of macrocyclic cobalt(III) chelates with (N,N,S,S)-donor atomic ligands in the cobalt(II)–dithiooxamide-formaldehyde and cobalt(II)–dithiooxamide-glyoxal systems in the Co2[Fe(CN)6]-gelatin-immobilized matrices

The complexing processes in the triple cobalt(II)–dithiooxamide-formaldehyde and cobalt(II)–dithiooxamide-glyoxal systems taking place in the cobalt(II)hexacyanoferrate(II) gelatin-immobilized matrix in contact with aqueous alkaline solutions (pH ca. 12) containing (dithiooxamide+formaldehyde) and (dithiooxamide+glyoxal), have been studied. Template synthesis leading to macrocyclic coordination compounds with tetradentate N,N,S,S-donor ligands-(2,8-dithio-3,7-diaza-5-oxanonan-dithioamide-1,9) and (2,7-dithio-3,6-diazaoctadien-3,5-dithioamide-1,8) with Co^II–Co^III redox-process occurs under these specific conditions where dithiooxamide, formaldehyde and glyoxal are the ligand synthons.     

Synthesis,characterization, and DNA interaction of mononuclear copper(II) and zinc(II) complexes having a hard–soft NS donor ligand

Knoevenagel condensate-based Schiff base ligands (L) containing N and S donor sites have been designed and synthesized [L = 3-cinnamalideneacetylacetonethiosemicarbazone (CAT)/3-cinnamalideneacetylacetoneethylthiosemicarbazone (CAET)/3-cinnamalideneacetylacetonephenylthiosemicarbazone (CAPT)]. They afford complexes of the type [ML] [M = Cu(II) and Zn(II)]. Both the ligands and their complexes were characterized by analytical and spectral data. Intercalative binding of these complexes with DNA has been investigated by electronic absorption spectroscopy, viscosity measurements, cyclic voltammetry, and differential pulse voltammetry. Electrophoretic study of the complexes indicates that they efficiently cleave supercoiled pUC19 DNA in the presence of hydrogen peroxide.     

An ESR study of the copper(II)–glycyl-l-serine and copper(II)–l-seryl-glycine systems by the simultaneous analysis of multi-component isotropic spectra. Formation constants and coordination modes

The formation constants and the isotropic ESR parameters (g-factors, ⁶³Cu, ⁶⁵Cu, ¹⁴N hyperfine coupling constants and relaxation parameters) of the various species were determined by the simultaneous analysis of a series of spectra, taken in a circulating system at various pH and ligand-to-metal concentration ratio. For both systems the new [CuLH]²⁺ complex was identified in acidic solutions. With the glycyl-l-serine ligand below pH 11.5 the same complexes and coordination modes are formed than with simple dipeptides. The side-chain donor group is bound only over pH 11.5 in the complex [CuLH₋₂(OH)]²⁻, where it is deprotonated and substitutes the carboxylate O in the third equatorial site. For the bis complex [CuLH₋₁(L)]⁻ an isomeric equilibrium was shown, where the difference between the isomers was based on which of the donor atoms of the ‘L’ ligand, the peptide O or the amino N, occupies the fourth equatorial position, and which one is coordinated axially. The l-seryl-glycine ligand forms the same species as simple dipeptides and glycyl-l-serine up to pH 8. The only difference is that the axial binding of the alcoholic OH group fairly stabilizes the bidentate equatorial coordination of the ‘L’ ligand through the amino N and peptide O atoms in the [CuL]⁺ complex as well as in the major isomer of the [CuLH₋₁(L)]⁻ complex. For this system we showed that (1) proton loss and the equatorial coordination of the alcoholic OH group occurs at relatively low pH (over pH 8–9), which results in the [CuL₂H₋₂]²⁻ complex with excess ligand, and also the newly identified species [Cu₂L₂H₋₄]²⁻: (2) this process is in competition with the proton loss of a coordinated water molecule. For both systems, the ESR-inactive species [Cu₂L₂H₋₃]⁻ was also shown.     

Nickel(II) and copper(II) – l-cysteine,l-methionine,l-tryptophan-nucleotide ternary complexes

Four new ternary complexes of Cu^II with l-methionine and the nucleotides 5AMP (adenosine 5-phosphate), 5GMP (guanosine 5-phosphate) and 5IMP (inosine 5-phosphate), and with l-tryptophan and 5AMP, were synthesized and characterized by elemental analysis and i.r. spectroscopy. One ternary complex of N^II with l-cysteine and 5IMP was also prepared and characterized. The study of the three ternary compounds of Cu^II, of general formulae Cu-5NMP-l-methionine, indicates coordination of the phosphate group and of N(7) of the purinic ring. l-Methionine is bound by the carboxylic and amino groups. The ternary complex obtained from a mixture of Cu-5AMP and l-tryptophan is a dimer in which the nucleotide bridges the two copper atoms. In the complex of Ni-5IMP and l-cysteine, the nucleotide seems to bind the metal through the N(7) of the heterocyclic ring, and the l-cysteine is coordinated as a bidentate chelate by the carboxyl and thiol groups. E.s.r. spectra of the copper complexes are in good agreement with the low symmetry structure proposed. The one-electron reduction potentials E_c(Fc⁺/Fc) (V) of Cu^II to Cu^I were established for the four copper complexes from cyclic voltammetry studies. The one-electron oxidation potential E_a(Fc⁺/Fc⁺) (V) of Ni^II to Ni^III was also measured for the nickel complex.     

Syntheses,crystal structures and magnetic properties of two cyano-bridged copper(I)–copper(II) mixed-valence complexes

Two cyano-bridged copper(II)–copper(I) mixed-valence assemblies, Cu(EAM)₂[Cu(CN)₂]₂ 1 (EAM?=?ethanolamine) and Cu(DETA)[Cu(CN)₂]₂·0.5H₂O 2 (DETA?=?diethylenetriamine), have been prepared and structurally and magnetically characterized. IR spectra indicate the presence of bridging cyano groups in both 1 and 2, confirmed by structure analyses; Cu(I)–CN–Cu(II), Cu(I)–CN–Cu(I) and Cu(I)–Cu(I) metal bond linkages are evident. In the lattice, a 3D network is formed by two [Cu(CN)₂]?^? units and one [Cu(EAM)₂]²⁺unit for 1. Variable temperature magnetic susceptibilities, measured in the 5–300?K range, indicate weak antiferromagnetic exchange interactions in complex 1.     

Linear oxalato- and 4,4′-dipyridyldisulfide-bridged copper(II) coordination polymer involving in situ ligand synthesis

The reaction of 1,3-bis(pyridyl-4-ylthio)propan-2-one with Cu(ClO₄)₂?·?6H₂O gave a new complex {[Cu₂(4PDS)₂(ox)(H₂O)₄](ClO₄)₂} _n (4PDS?=?4,4′-dipyridyldisulfide, ox?=?oxalate), with 4PDS and ox being created by the Cu(II)-assisted oxidation of 1,3-bis(pyridyl-4-ylthio)propan-2-one. The complex determined by X-ray crystallography is a 1D polymer, in which metallacycles formed by two 4PDS and two Cu(II) ions are further bridged through ox anions. It crystallizes in the orthorhombic system, space group Fddd, with lattice parameters a?=?15.106(2), b?=?23.667(4), c?=?27.637(3)?Å and Z?=?8.     

A novel lariat-silacrown ether based in sol–gel process: synthesis, characterization and interaction study with the copper(II) ion

The synthesis and characterization of the lariat-silacrown ether (Sila15NH??IUPAC name: 3-[1-[[1-(3-aminopropyl)-2,5,8,11,14-pentaoxa-1-silacyclotetradec-1-yl] oxy]-2,5,8,11,14-pentaoxa-1-silacyclotetradec-1-yl]propan-1-amine) and its complex with copper(II) ion, Cu(II)?CSila15NH, are reported in this work. Tetraethylene glycol, 3-aminopropyl triethoxysilane and metallic sodium were employed as precursors and the lariat-silacrown ether obtained in a good yield (64?%) was characterized by elemental analysis, infrared spectroscopy (FTIR) and nuclear magnetic resonance of ¹H, ¹³C and ²⁹Si. The Cu(II)?CSila15NH was characterized by elemental analysis and FTIR. The straightforward Cu(II) complex formation suggests this property could be explored for analytical purposes.     

DNA-binding and photocleavage studies of metallofluorescein–porphyrin complexes of zinc(II) and copper(II)

The DNA-binding behaviors of the fluorescein?Cporphyrinatozinc(II) complex Zn(Fl-PPTPP) (Fl-PPTPP?=?5-(4-fluoresceinpropyloxy)phenyl-10,15,20-triphenylporphyrin) and fluorescein?Cporphyrinatocopper(II) complex Cu(Fl-PPTPP) with calf thymus DNA (CT-DNA) were investigated by UV?CVis absorption titrations, fluorescence spectra, viscosity measurements, thermal denaturation and circular dichroism. The results suggest that both complexes interact with CT-DNA by intercalation. In addition, their photocleavage reactions with pBR322 supercoiled plasmid DNA were investigated. Both complexes exhibit significant DNA cleavage activity, and singlet oxygen may play an important role in these reactions.     

Cyanide-bridged manganese(II) and chloride-bridged copper(II) complexes with 2-pyridineethanol: synthesis,structural characterization and C-H⋯M interactions

[Mn(hepH)₂Ni(μ-CN)₂(CN)₂]_n (1) and [Cu₂(μ-Cl)₂(μ-hep)₂]_n (2) (2-pyridineethanol abbreviated to hepH) have been synthesized and characterized by FT-IR and Raman spectroscopies, elemental analyses, and single-crystal X-ray diffraction. X-ray single-crystal structure analysis reveals that the structures of 1 and 2 consist of 1-D infinite chains. The coordination environment of Mn(II) was identified as distorted octahedral, whereas Ni(II) has a square planar geometry in 1. Each Cu(II) in 2 adopts a distorted square pyramidal geometry in which the basal plane is constructed by oxygen and nitrogen atoms from hep and a bridging chloride ligand, respectively, and the apical position is occupied by the other chloride. The 1-D chains in 1 and 2 are extended into a 2-D supramolecular network by O?H?N and weak C?H?Cl hydrogen bonds, respectively. Adjacent 2-D layers are further connected by C?H?M interactions resulting in the formation of 3-D supramolecular networks. The most remarkable properties of complexes are the presence of close C–H?M interactions with distance values of 2.58 and 2.93 Å between H?Ni and H?Cu, respectively. The H?Ni interaction distance is shorter than the corresponding values of other tetracyanonickelate(II) complexes.     

Synthesis,spectral, magnetic,electrochemical and catalytic studies of cyclam-based copper(II) and nickel(II) complexes–effect of N-substitution

New N-substituted cyclam ligands 1,8-[bis(3-formyl-2-hydroxy-5-methyl)benzyl]-1,4,8,11-tetraazacyclotetradecane, 1,8-[bis(3-formyl-2-hydroxy-5-methyl)benzyl]-4,11-dimethyl-1,4,8,11-tetraazacyclotetradecane, 1,8-[bis(3-formyl-2-hydroxy-5-bromo)benzyl]-1,4,8,11-tetraazacyclotetradecane, and 1,8-[bis(3-formyl-2-hydroxy-5-bromo)benzyl]-4,11-dimethyl-1,4,8,11-tetraazacyclotetradecane (L¹–L⁴) were synthesized and mononuclear copper(II) and nickel(II) complexes prepared. The ligands and complexes were characterized by elemental analysis, electronic, IR, ¹H NMR and ¹³C NMR spectral studies. N-alkylation causes red shifts in the λ_max values of the complexes. Copper(II) complexes show one-electron, quasi-reversible reduction waves in the range ?1.04 to ?1.00 V. The nickel(II) complexes show one-electron, quasi-reversible reduction waves in the range ?1.18 to ?1.30 V and one-electron, quasi-reversible oxidation waves in the range +1.20 to +1.40 V. The reduction potential of the copper(II) and nickel(II) complexes of the ligands L¹ to L² and L³ to L⁴ shift anodically on N-alkylation. The ESR spectra of the mononuclear copper(II) complexes show four lines, characteristic of square-planar geometry with nuclear hyperfine spin 3/2. All copper(II) complexes show a normal room temperature magnetic moment value μ_eff?=?1.70–1.74 BM which is close to the spin only value of 1.73 BM. Kinetic studies on the oxidation of pyrocatechol to o-quinone using the copper(II) complexes as catalysts and on the hydrolysis of 4-nitrophenylphosphate using the copper(II) and nickel(II) complexes as catalyst were carried out. The tetra-N-substituted complexes have higher rate constants than the corresponding disubstituted complexes.     

Synthesis and characterization of a dipeptide–copper(II)– 2-aminomethylbenzimidazole ternary complex

A new ternary complex [Cu(glygly)(AMBZ)(H₂O)]Cl·H₂O (1) (glygly?=?glycylglycine anion, AMBZ?= 2-aminomethylbenzimidazole) has been prepared and characterized by single-crystal X-ray diffractometry and ESR, electronic and IR spectroscopy. The copper(II) ion has a slightly distorted square-pyramidal coordination, being equatorially coordinated by the bidentate 2-aminomethylbenzimidazole and the bidentate glycylglycine anion and axially by a water molecule. The individual complex molecules are hydrogen bonded to their neighbors, forming a polymeric hydrogen-bonded lattice. Spectroscopic data are in accordance with the crystal structure.     

Synthesis and properties of double copper(I)–nickel(II) sulfite

Pourbaix diagrams of Cu–H₂SO4–H₂O and Ni–H₂SO₄–H₂O systems have been refined, and stability regions of the sulfite phases have been determined. State diagrams of double copper(I)–copper(II) and copper(I)–nickel(II) sulfites have been constructed. Double copper(I)–nickel(II) sulfite has been isolated from aqueous solutions saturated with sulfur dioxide. The solutions at different ratios of the metals have been studied by spectrophotometry; the isolated double sulfite has been studied by X-ray diffraction, IR spectroscopy, dispersion analysis, and thermal analysis. Fundamentals of thermodynamic prognostication of the Cu₂SO₃·MSO₃ double sulfites synthesis have been elaborated.