Complexation copper(II) or magnesium ions with d-glucuronic acid – potentiometric,spectral and theoretical studies

Results of potentiometric and spectral studies have shown that in d-glucuronic acid (GluA) with Cu²⁺ or Mg²⁺ systems, the complexes ML and ML(OH)_x are formed. Overall stability constants (log β) and equilibrium constants (log K_e) were calculated for all complex forms. The mode of coordination for each form was concluded on the basis of spectral values, Vis, EPR, and chemical shifts in the ¹³C NMR. According to spectral analysis, Cu(GluA) exists in two possible forms, which confirm the occurrence of the coordination dichotomy in the system. The main center of interactions in the hydroxyl complexes Cu(GluA)(OH)_x and MgGluA are oxygens from the carboxyl group. Differences in the coordination mode in the copper(II) and magnesium systems at low pH were observed.     

Features of сhitosan interaction with copper(II) and cobalt(II) tetrasulfophthalocyanines

The interaction of chitosan with copper(II) and cobalt(II) tetrasulfophthalocyanines is studied by spectral methods. The main parameters of binding of chitosan to anionic metal phthalocyanines are determined by Scatchard analysis. It is found that the formation of the polymer complex is considerably contributed by donor?acceptor interactions between the coordinately unsaturated metal phthalocyanine and chitosan amino groups. Сhitosan reacts with a monomeric cobalt(II) tetrasulfophthalocyanine, whereas copper(II) tetrasulfophthalocyanine in its complex with chitosan remains in the dimeric state. The reaction centers responsible for the Cu(SO₃H)₄Pc)₂–chitosan and Co(SO₃H)₄Pc–chitosan complexes are revealed by means of IR spectroscopy.     

Synthesis, structural characterisation and thermal decomposition studies of some 2,4′-bipyridyl complexes with cobalt(II), nickel(II) and copper(II)

2,4-Bipyridyl (2,4-bipy orL) complexes with cobalt(II), nickel(II) and copper(II) of the formulae M(2,4-bipy)₂(CH₃COO)₂·2H₂O (M(II) = Co, Ni, Cu), Co(2,4-bipy)₂SO₄·3H₂O or Ni(2,4-bipy)₂SO₄·4H₂O have been prepared and their IR and electronic (VIS) spectra are discussed. The thermal behaviour of the obtained compounds has also been studied. The intermediate products of decomposition at different temperatures have been characterized by chemical analysis and X-ray diffraction.We thank dr. A. Malinowska for performing VIS spectra. This work was supported by the KBN project No. PB 0636/P3/93/04.     

Physicochemical studies of metal haloacetates—VII magnetic and IR studies of copper(II) bromo- and iodoacetates

The bromo- and iodoacetates of copper(II) have been prepared and their magnetic properties examined between 80 and 300°K. The hydrated and anhydrous monobromo-, monoiodo- and diiodoacetates appear to be essentially dimeric with a slight contamination by a monomer or polymer. Hydrated dibromoacetate and anhydrous di- and tribromoacetates occur in more than one form, while the hydrated tribromoacetate is monomeric.     

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.     

Complexation of copper(II) with 2′,2′-dialkyl-para-tert-butylbenzohydrazides

The complexation of copper(II) with 2′,2′-dimethyl-, 2′,2′-dibutyl-, and 2′,2′-diisobutyl-para-tert-butylbenzohydrazide in water-ethanol media was studied. The reagents (HL) formed [Cu(HL)]²⁺ and [Cu(HL)₂]²⁺ cationic complexes in a weakly acidic medium and uncharged CuL₂ complexes in an alkaline medium. logK _st was calculated for these complexes. The effect of 2′,2′-alkyl radicals on the stability of the complexes was considered. The obtained results were compared with data on the complexation of copper(II) ions with 2′,2′-dialkylbenzohydrazides.     

Complexation of palladium(II) with thiocyanate – a spectrophotometric investigation

Complex-formation of Pd(II) with thiocyanate has been investigated by spectrophotometry at 25?°C and an ionic strength of 1.0?M. The formation constants, β_n, for the palladium(II) thiocyanate complexes [Pd(SCN)_n(H₂O)_4–n]^2–n (n?=?0–4), have been determined and the values are: log?β₁?=?8.14, log?β₂?=?15.46, log?β₃?=?21.94, and log?β₄?=?27.42. These complexes are generally accepted to be square planar. However, a five-coordinate species, i.e. [Pd(SCN₅]^3–, with a formation constant of log?β₅?=?31.94 seems to exist and is proposed to be square pyramidal. Molar absorption spectra for all the complexes in question have been obtained.     

Synthesis,structure and magnetic studies of copper(II)-nickel(II) complexes withN,N′-bis(2-aminopropyl)oxamidocopper(II)

Three novel heterobinuclear complexes have been prepared and identified as [Cu(oxap)Ni(L)₂](ClO₄)₂·ξH₂O, where oxap denotes theN,N′-bis(2-aminopropyl)oxamido dianion and L denotes 2,2′-bipyridine (bipy), 1,10-phenanthroline (phen) or 5-nitro-1,10-phenanthroline (NO₂-phen). The crystal structure of [Cu(oxap)Ni(phen)₂]-(ClO₄)₂·2H₂O has been determined. Crystal data: triclinic, space group , a=12.079 (6), b=12.409 (4), c=17.261 (8) ?, α=70.91 (2), β=86.72 (4), γ=89.19 (3)^o. At room temperature, Z=2. The Cu^II is in a square planar environment and the Ni^II is in an octahedral environment. The Cu−Ni distance is 5.292 ?. The temperature dependences of the magnetic susceptibilities of [Cu(oxap)Ni(phen)₂]-(ClO₄)₂·2H₂O and [Cu(oxap)Ni(bipy)₂](ClO₄)₂ have been studied in the 4.2–300 K range, giving the exchange integral J=−92.4 cm⁻¹ for bipy and J=−94.3 cm⁻¹ for phen. These results are commensurate with antiferromagnetic interactions between the adjacent metal ions.     

Solution and structural studies of the Cd(II) – Aconitate system

The complexing ability of the binary system trans-aconitic acid (H₃L) with regard to Cd(II) and the crystal structures of the binary system Cd(II)–(H₃L), [Cd₃L₂(H₂O)₆] n(1) and ternary systems of Cd(II)–(H₃L)–Lewis base [Lewis base = 1,10-phenanthroline (2) and 2,2′-bipyridine (3)] have been determined. Compound 1 is a rare binodal four-connected three-dimensional (3D) metal-organic framework possessing a moganite (mog) topology. Compounds 2 and 3 represent infinite one-dimensional (1D) chains forming three-dimensional metal-supramolecular structures through H-bond and π–π stacking interactions. All compounds have been characterized by spectroscopic and thermogravimetric techniques.     

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.     

Synthesis and crystal structure of 2′-(3,5-dioxo-1,2,4-triazinane-1-yl)acetic acid and the product of its reaction with copper(II) chloride

A new organic compound, 2-(3,5-dioxo-1,2,4-triazinane-1-yl)acetic acid, was prepared by transit template synthesis, and its crystal structure was determined. The ability of this compound to form stable metal complexes, where it acts as an N,O-chelating ligand, was demonstrated using its Cu(II) compound as an example.Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 3, 2005, pp. 187–194.Original Russian Text Copyright © 2005 by Filippova, Bologa, Simonov, Gdaniec, Gerbaleu.This revised version was published online in April 2005 with a corrected cover date.This revised version was published online in April 2005 with a corrected cover date.     

Structural, MALDI-TOF-MS, magnetic and spectroscopic studies of new dinuclear copper(II), cobalt(II) and zinc(II) complexes containing a biomimicking μ-OH bridge

The Py(2)N(4)S(2) octadentate coordinating ligand afforded dinuclear cobalt, copper and zinc complexes and the corresponding mixed metal compounds. The overall geometry and bonding modes have been deduced on the basis of elemental analysis data, MALDI-TOF-MS, IR, UV-vis and EPR spectroscopies, single-crystal X-Ray diffraction, conductivity and magnetic susceptibility measurements. In the copper and zinc complexes, a μ-hydroxo bridge links the two metal ions. In both cases, the coordination geometry is distorted octahedral. Magnetic and EPR data reveal weakly antiferromagnetic high spin Co(II) ions, compatible with a dinuclear structure. The magnetic characterization of the dinuclear Cu(II) compound indicates a ferromagnetically coupled dimer with weak antiferromagnetic intermolecular interactions. The intra-dimer ferromagnetic behaviour was unexpected for a Cu(II) dimer with such μ-hydroxo bridging topology. We discuss the influence on the magnetic properties of non-covalent interactions between the bridging moiety and the lattice free water molecules.     

Complexes of copper(II) with the β-blocker atenolol

Mono- and binuclear copper(II) complexes with atenolol (HAt) can be obtained, depending on the reaction conditions. The mononuclear violet complex cation has the general formula Cu(HAt)₄ ²⁺ with an elongated octahedral geometry. The two ligands in the equatorial plane are bound in a bidentate fashion through the hydroxyl oxygen and amino nitrogen, while the other two atenolol molecules in axial position are coordinated in a monodentate way. The binuclear green complex Cu₂At₂Cl₂, is neutral, where atenolol acts as a bidentate (O^–, NH) bridging ligand. The bridge between the two Cu atoms is realized by the deprotonated oxygen of the alcohol group.     

Synthesis,spectral, magnetic,electrochemical and kinetic studies of copper(II), nickel(II) and zinc(II) complexes derived from a phenol-based unsymmetrical “end-off” ligand

A new unsymmetrical end-off, aminomethylated N-methylpiperazine and aminomethylated diethanolamine armed binucleating ligand, 2-[bis(2-hydroxyethyl)aminomethyl]-6-[(4-methylpiperazin-1-yl)methyl]-4-formylphenol (HL), was synthesized by following sequential aromatic Mannich reactions. Mononuclear and binuclear Cu(II), Ni(II) and Zn(II) complexes were synthesized and characterized by elemental and spectral analysis. The EPR spectrum of the mononuclear copper complex shows four hyperfine splittings and the binuclear complex shows a broad signal due to anti-ferromagnetic interaction. The room temperature magnetic moment of the mono and binuclear copper complexes are 1.72 and 2.68 BM, respectively. Variable temperature magnetic moment study of the binuclear copper(II) complex shows weak antiferromagnetic coupling (?2J value, 21 cm^?1). The mononuclear Ni(II) complex is square planar and diamagnetic. The six-coordinate binuclear Ni(II) complex shows a magnetic moment of 3.06 BM. Electrochemical studies of the complexes reveal that all mononuclear complexes show a single irreversible one-electron reduction wave and the binuclear complexes show two irreversible one-electron reduction waves in the cathodic region. Catecholase activity of copper(II) complexes using pyrocatechol as a model substrate and the hydrolysis of 4-nitrophenylphosphate using copper(II), nickel(II) and zinc(II) complexes as catalysts showed that binuclear complexes have higher rate constants than corresponding mononuclear complexes.     

Synthesis, characterization, spectrophotometric, structural and antimicrobial studies of the newly charge transfer complex of p-phenylenediamine with π acceptor picric acid

Charge transfer complex (CTC) of donor, p-phenylenediamine (PPD) and acceptor, 2,4,6-trinitrophenol (picric acid) has been studied in methanol at room temperature. The CT complex was synthesized and characterized by elemental analysis, FTIR spectra, 1H NMR spectroscopy and electronic absorption spectra which indicate the CT interaction associated with proton migration from the acceptor to the donor followed by hydrogen bonding via N+-H?O-. The thermal stability of CT complex was studied using TGA and DTA analyses techniques. The CT complex was screened for its antifungal activity against Aspergillus niger (Laboratory isolate), Candida albicans (IQA-109) and Penicillium sp. (Laboratory isolate) and antibacterial activity against two Gram-positive bacteria Staphylococcus aureus (MSSA 22) and Bacillus subtilis (ATCC 6051) and two Gram-negative bacteria Escherichia coli (K 12) and Pseudomonas aeruginosa (MTCC 2488). It gives good antimicrobial activity. The stoichiometry of the CT complex was found to be 1:1. The physical parameters of CT complex were evaluated by the Benesi-Hildebrand equation. On the basis of the studies, the structure of CT complex is [(PPDH)+(PA)-], and a general mechanism for its formation is proposed.     

Synthesis and magnetic properties of copper(II)-cobalt(II) complexes ofN,N′-1,2-propanedisalicylamidatocuprate(II)

Summary The binuclear metal complexes [Cu(sampn)Co(L)₂] (L=bipy, phen), have been prepared by the reaction of sodiumN,N-1,2-propanedisalicylamidatocuprate(II) heptahydrate, Na₂[Cu(sampn)] 7H₂O, with a divalent metalion, and 2,2-bipyridine or 1, 10-phenathroline. The complexes were characterized by variable-temperature magnetic susceptibility measurements; the results indicate that a weak antiferromagnetic spin-exchange interaction operates between the metal ions.     

Synthesis of new unsymmetrical “end-off” phenoxo bridged copper(II), nickel(II) and zinc(II) complexes: spectral,magnetic, electrochemical,catalytic, and antimicrobial studies

A new class of unsymmetrical end-off, aminomethylated N-methylpiperazine and aminomethylated diethanolamine binucleating ligands, 2-[bis(2-hydroxyethyl)aminomethyl]-6-[(4-methylpiperazin-1-yl)methyl]-4-methylphenol (HL¹) and 2-[bis(2-hydroxyethyl)aminomethyl]-6-[(4-methylpiperazin-1-yl)methyl]-4-acetylphenol (HL²) were synthesized by following sequential aromatic Mannich reactions. Their mononuclear and binuclear Cu(II), Ni(II) and Zn(II) complexes have been synthesized and their formulation was confirmed by analytical and spectral analysis. The mononuclear Cu(II) complexes have a magnetic moment value close to the spin only value with four hyperfine EPR signals. The binuclear Cu(II) complexes have an antiferromagnetic interaction with a broad EPR signal. Electrochemical studies of the complexes reveal that all the redox processes are irreversible. Catecholase activity of Cu(II) complexes and the hydrolysis of 4-nitrophenylphosphate using Cu(II), Ni(II), and Zn(II) complexes were carried out. Spectral, magnetic, electrochemical, and catalytic behaviors of the complexes are compared on the basis of the p-substituent of the phenolic ring. Some of the complexes show significant growth inhibitory activity against pathogenic bacteria and fungi.     

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.     

Synthesis and magnetic properties of heterobinuclear copper(II)–iron(II) complexes with N,N′-bis(2-aminopropyl)oxamidocopper(II)

Six new -oxamido heterobinuclear complexes, namely [Cu(oxap)Fe(L)2]SO4, where oxap denotes the N,N-bis(2-aminopropyl)oxamido dianion and L represents 1,10-phenanthroline (phen); 5-nitro-1,10-phenanthroline (NO2-phen); 5-chloro-1,10-phenanthroline (Cl-phen); 5-methyl-1,10-phenanthroline (Me-phen); 2,2-bipyridine (bpy); and 4,4-dimethyl-2,2-bipyridine (Me2bpy), have been synthesized and characterized by elemental analyses, i.r. spectra, electronic spectra, magnetic moments (at room temperature) and molar conductivity measurements. The temperature dependent magnetic susceptibilities of [Cu(oxap)Fe(bpy)2]SO4 (1) and [Cu(oxap)Fe(phen)2]SO4 (2) have been studied in the 4.2–300K range, giving the exchange integrals J=–20.9cm–1 for (1) and J=–22.5cm–1 for (2). These results are commensurate with antiferromagnetic interactions between adjacent metal ions within each molecule.