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.     

Soft template synthesis in copper(II)–dithiooxamide–methanal,copper(II)–dithiooxamide–ethanal and copper(II)–dithiooxamide–propanone triple systems in a copper(II)hexacyanoferrate(II) gelatin-immobilized matrix

Novel complexing processes in the Cu^II–dithiooxamide–methanal, Cu^II–dithiooxamide–ethanal and Cu^II–dithiooxamide–propanone triple systems proceeding under specific conditions, to copper(II)hexacyanoferrate(II) gelatin-immobilized matrix systems in contact with aqueous-alkaline (pH 12) solutions containing dithiooxamide and methanal, ethanal or propanone, have been studied. It has been shown that template synthesis leading to the formation of macrocyclic coordination compounds (2,8-dithio-3,7-diaza-5-oxanonandithioamide-1,9)copper(II), (2,8-dithio-3,7-diaza-4,6-dimethyl-5-oxanonandithio-amide-1,9)copper(II) and (4,4,6-trimethyl-2,8-dithio-3,7-diazanonen-6-dithioamide-1,9)copper(II), respectively, takes place under such conditions. Dithiooxamide, methanal, ethanal and propanone act as ligand synthons in these processes.     

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.     

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.     

μ-phenoxo-bridged binuclear copper(II) complexes

Summary Two -phenoxo-bridged binuclear copper(II) complexes, [Fsal(GG)₂Cu₂Cl₃]·H₂O (1) containing an exogenous chloride-bridge and [Fsal(GG)₂Cu₂(OH)](ClO₄)₂·H₂O (2) containing an exogenous hydroxide-bridge, where {Fsal(GG)₂ = 2,6-bis[N-(acetylglycine)-imino-methylene]-4-methylphenol}, were synthesized. The complexes were characterized be several spectroscopic methods. According to variable temperature magnetic susceptibility measurements (4–300 K), the hydroxide-bridged complex (2) has a weak antiferromagnetic spin exchange integral (J =- 23.6 cm), while the chloride complex (1) has an unusual weak ferromagnetic spin exchange integral (J = + 30.9 cm); both complexes have similar optical spectra in the aqueous solutions.     

Reevaluation of copper(I) affinity for amyloid-β peptides by competition with ferrozine--an unusual copper(I) indicator

The association constant of ferrozine (5,6-diphenyl-3-(2-pyridyl)-1,2,4-triazine-4,4'-disulfonic acid) with Cu(I) to form the chromophoric [Cu(I)(Fz)(2)](3-) complex was determined by UV/Vis titration experiments in Hepes buffer (0.1 M, pH 7.4). An association constant close to 10(12) M(-2), which is significantly weaker than those of the well-known, water-soluble, Cu(I) chelators bicinchoninic acid and 2,9-dimethyl-4,7-diphenyl-1,10-phenantroline disulfonic acid, was found. The [Cu(I)(Fz)(2)](3-) chromophore was used in UV/Vis competition experiments to determine Cu(I) binding affinity for the amyloid-β peptide involved in Alzheimer's disease and for a series of pertinent mutants. An association constant of approximately 10(7) M(-1) was found; this is much weaker than that reported for dithiothreitol and confirms that imidazoles are harder ligands than thiolates. Each His mutation (H6A, H13A, and H14A) impacts the peptide affinity for Cu(I). The native human amyloid-β peptide was found to be a fourfold-stronger Cu(I) ligand than the murine peptide, which differs by three point mutations (R5G, Y10F, and H13R) from the human one.     

Disposition of copper(II) inβ-cyclodextrin

Distances of glucose protons in-cyclodextrin (BCD) from copper(II) in copper(II)--cyclodextrin have been determined from¹H NMR spin-lattice relaxation time (T ₁) measurements for the first time. Very lowT _1p /T _2p values indicated the dipolar mechanism to be the most dominant one in determining the paramagnetic contribution to relaxation. The distances of copper(II) from BCD glucose protons indicated copper(II) to be present almost in the centre, inside the cavity in the same plane as H-1 and H-4. An average distance of about 5.0–5.9 Å was obtained for copper(II) from the H-2, H-3, H-1, H-4 and H-6 a and b protons in BCD.     

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.     

Structure of bis-(1,1,1-trifluoro-2-(methylimino)pentanoato-4)copper(II). Thermal properties of N-methylsubstituted copper(II) β-iminoketonates

The single crystal X-ray diffraction (XRD) method was used to determine the structure of the [Cu(mi-tfac)₂] (mi-tfac = MeC(O)CHC(NMe)CF₃) complex at the temperature of 150 K. The crystallographic data are as follows: space group Pnna, a = 11.8798(16) Å, b = 12.0315(16) Å, c = 10.6259(14) Å, V = 1518.8(4) ų, Z = 4, R = 0.0288. The structure is molecular, the coordination environment of copper in the molecule adopts a distorted tetrahedral geometry. The Cu–O and Cu–N distances are 1.9182(13) Å and 1.9610(16) Å respectively, the OCuN chelate angle is 94.18(5)°. The thermal properties of the compounds [Cu(mi-tfac)₂] and [Cu(RC(O)CHC(NMe)R)₂] (R = Me, ^t Bu) in the condensed phase have been studied by the methods of thermogravimetry and differential scanning calorimetry. The thermodynamic characteristics of the melting processes have been determined.     

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).     

Synethesis and Crystal Structure of Bi(ethylenediamine)copper Tetracyanonickelate(Ⅱ)

The crystal structure of the title compound C8H16CuN8Ni has been determined by single crystal X-ray diffraction. The crystal is triclinic with space group P1, a=6.494(3), b=7.270(4), c=7.936(5) .A, α=106.67(3), β=91.33(4), γ=106. 80(6)°, V=341. 3(3) A3, Z==1, Mr=346. 54, F(000)=177, μ=2. 933mm-1, Dc= 1. 686 Mg/m3. The final R factor is 0. 0603 for 1214 unique ob24- served reflections [I≥2σ(I)]. The structure consists of [Cu(en)2]2+ (eh=ethylenedi amine) cations and [Ni(CN)4]2- anions linked together by two of the CN groups (the remaining two act as unidentate ligands) to form infinite chains, in the chain, the hy between the interchains also exist, with distances of 3. 160 and 3. 124 A , so it forms a three-dimensional structure of the title compound.     

2,4′-Bipyridyl complexes with silver(I) and copper(II)

Summary Ag^I and Cu^II complexes with 2,4-bipyridyl (2,4-bipy or L) with the general formulae AgL₂X (where X = NO _inf3 ^sup– or ClO₄ ^-), CuL₂X₂·2H₂O (X = Cl^- or Br^-), CuL₄SO₄·4H₂O, CuL₄(NO₃)₂·2H₂O and CuL₄(ClO₄)₂·H₂O have been isolated pure and characterized by analytical, spectral and magnetic measurements. The thermal decomposition of these complexes was studied under non-isothermal conditions in air.     

Condensation of bis(β-alaninato)copper(II) with formaldehyde and ammonia

Various complexes have been prepared by the template condensation of -amino acids with formaldehyde or acetaldehyde in the presence of metal ions(^1–5). In particular, glycine has received much attention(^1–4). For example, (3N, 7N-1,3,5,7-tetraazabicyclo[3.3.1]nonyl)-diacetato nickel(II) (1) has been prepared by condensing bis(glycinato)nickel(II) dihydrate with formaldehyde and ammonia at pH 8.5⁴. More recently⁵, complex (2) has been prepared by condensing bis(L-alaninato)copper(II) with formaldehyde and ammonia. These reactions are interesting for the following reasons:

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.     

An MCl inf4 p2− moiety (M = copper,zinc, cadmium and mercury) stabilized by bis(ethylenediamine)copper(II) cation

Summary New ionic bimetallic complexes of the type [Cu(en)₂]-[MCl₄], where M = Cu^II, Zn^II, Cd^II and Hg^II, were prepared by reacting bis(ethylenediamine)copper(II) dichloride (1 mol) with copper, zinc, cadmium and mercury dichlorides (1 mol) in absolute alcohol. Elemental analyses, conductivity and magnetic susceptibility measurements, and spectroscopic data (such as i.r., u.v.-vis. and e.p.r.) confirm that the compounds are 22 electrolytes in MeOH and that the copper(II) ion is paramagnetic, maintaining its square-planar geometry, while metal ions in the anionic moiety of the complexes achieve their usual tetrahedral environment. An augmented magnetic moment has been observed in the [Cu(en)₂] [CuCl₄] complex, which is attributed to the ferromagnetic effect and TIP.Author to whom all correspondence should be directed.     

Formation of a mixed valence copper(II)–copper(I) coordination polymer {[Cu(1,2-pn)2(μ3-I)Cu2(μ2-I)3(CH3CN)]⋅CH3CN}n: in situ reduction of copper(II) at ambient condition

A mixed valence copper(II)–copper(I) coordination polymer has been synthesized starting from a copper(II) salt at ambient condition and characterized by IR and Raman spectra and single crystal X-ray diffraction. The structure of the complex consists of a 1-D infinite chain with repeating unit [Cu(1,2-pn)₂(μ₃-I)Cu₂(μ₂-I)₃(CH₃CN)] and a free CH₃CN, where 1,2-pn = 1,2-diamino-1-propene. The complex shows a very short copper(I)–copper(I) distance (2.412?Å).     

Study of liquid-crystalline copper(II) β-enaminoketonates by EPR

The structure of the chelate unit and magnetic properties of the homologous series of liquid-crystalline bis{1-[4-(4-alkoxybenzoyloxy)phenyl]-3-amyl-1-aminoprop-1-en-3-onate)copper(II) complexes was studied by EPR. The direction of the orientation of liquid crystal molecules in an external magnetic field in the mesophase state was determined. The complexes have a square-planar structure of the chelate unit determining their mesomorphic properties.     

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.     

Mechanism of electrochemical synthesis of copper(II) β-diketonates

Formation of copper -diketonates in electrolysis of a solution of acetylacetone in acetonitrile in the presence of oxygen, with tetraethylammonium bromide as supporting electrolyte, was studied.Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 11, 2004, pp. 1804–1807.Original Russian Text Copyright © 2004 by Kostyuk.     

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.