Synthesis of copper(II) coordination compounds with benzoxazine derivatives

Copper(II) complexes with 1,2-dihydro-4H-3,1-benzoxazine (HL) derivatives, CuLOH, were prepared by anodic electrosynthesis. The use of an amalgamated copper anode resulted in an increase in the electrosynthesis rate. It follows from the IR spectra of the products that the benzoxazine ring in the ligand molecule is opened upon complexation, while a six-membered chelate ring involving the oxygen atom of the deprotonated phenol group and the imine nitrogen atom is formed.     

Synthesis and properties of tetraalkoxy aluminates and allied derivatives of copper(II)

Tetraisopropoxyaluminate of copper undergoes alcoholysis reactions with various alcohols and acetylacetone to yield Cu[Al(OR)₄]₂, where RO = methoxy, ethoxy, 2,2,2-trifluoroethoxy, 2,2,2-trichloroethoxy, 1,3,-dibromo-2-propoxy, n-butoxy, teriary butoxy and pentoxy amyl and acetylacetone. Various physico-chemical studies like infrared, visible reflectance, and electron spin resonance and magnetic susceptibility measurements as well as molecular weight and elemental analysis have been made to throw light on the structural features of these derivatives. These studies suggest an octahedral environment for copper(II) in these derivatives.     

Synthesis and study of copper(II), nickel(II), and cobalt(II) complex compounds with dihydrobenzoxazine derivatives

Complex compounds ML₂ of copper(II), nickel(II), and cobalt(II) with 2-(2-hydroxy-5-nitrophenyl)-4,4-diphenyl-1,4-dihydro-2H-3,1-benzoxazine and 2-(2-hydroxyphenyl)-4,4-diphenyl-1,4-dihydro-2H-3,1-benzoxazine (HL) were prepared by electrochemical and chemical syntheses. The complex formation involves the azomethine form of the ligand and gives a six-membered chelate cycle comprising deprotonated phenol and azomethine groups. The coordination entity has a planar structure with trans arrangement of the nitrogen and oxygen atoms.     

Synthesis and magnetic properties of copper (II)-manganese (II) compounds with N,N′-ethylenedisalicylamidatocuprate(II)

By the reaction of sodium N,N′-ethylenedisalicylamidatocuprate ( I ) pentahydrate, Na₂[Cu(samen)]·5H₂O, with a manganese ( I ) salt and 2,2′-dipyridyl (bpy) or 1,10-phenanthroline (phen), the binuclear metal complexes [Cu(samen) Mn(L)₂] (L ? bpy, phen) have been synthesized. Based on IR, elemental analyses and electronic spectra, the complexes are proposed to consist of a four-coordinated Cu( I ) in a distorted planar environment and Mn( I ) in a distorted octahedron. The complexes have been characterized with variable-temperature magnetic susceptibility (4.2—300 K) and the susceptibility data were least-squares fit to susceptibility equation derived from the spin Hamiltonian including single-ion zero-field interaction for Mn²⁺ ion, H?—2JS₁·S₂—DS, where D is the axial zero-field splitting parameter for the Mn(II) ion. The exchange integral, J, was found to be —34.6 and —28.8 cm^?1 for [Cu(samen)Mn(bpy)₂] and [Cu(samen)Mn(phen)₂] respectively. The weak antiferromagnetic spin-exchange interaction can be interpreted by considering σ-π exchange pathway.     

Synthesis and spectroscopic properties of some thermochromic copper(II) complexes ofN(2-aminoethyl) heterocyclic derivatives

Summary Compounds of the type CuL₂X₂, where L =N(2-aminoethyl)piperazine [N(2-amet)pipz],N(2-aminoethyl)-pyrrolidine [N(2-amet)pyrr] andN(2-aminoethyl)morpholine [N(2-amet)morph] and X = BF ₄ ^– , ClO ₄ ^– and NO ₃ ^– , have been prepared and characterized by means of magnetic moments, e.s.r., electronic and i.r. spectra. Only forN(2-amet)pyrr and Cu[N(2-amet)morph]₂(NO₃)₂ complexes, do the electronic and i.r. spectra suggest polyanion coordination. In particular, as their electronic and i.r. spectra in the 293–393K range are temperature-dependent, it may be ascribed to the presence of a reversible continuous thermochromism arising from a temperature-dependent axial interaction between the anion and the CuN₄ plane, which diminishes as the temperature increases. In all the other complexes, the thermochromism may be associated with a geometry which is more planar forN(2-amet)morph than forN(2-amet)pipz derivatives.     

Synthesis,characterization, and structural determination of copper(II) complexes with alkyl derivatives of hydroxybenzophenones

Four mononuclear copper(II) complexes, [Cu(LFQM-115)₂] (1), [Cu(LFQM-116)₂] (2), [Cu(LFQM-117)₂] (3) and [Cu(octyloxy)₂] (4) [LFQM-115 = 2-hydroxy-4-O-methylbenzophenone (C₁₄H₁₁O₃), LFQM-116 = 2-hydroxy-4-O-butylbenzophenone (C₁₇H₁₈O₃), LFQM-117 = 2-hydroxy-4-O-(33-dimethylallyl)benzophenone (C₁₈H₁₈O₃) and octyloxy = 2-hydroxy-4-O-octylbenzophenone (C₂₁H₂₅O₃)], have been prepared and investigated by infrared spectroscopy, thermal analysis, and powder and single crystal X-ray diffraction. Even though the synthesis and infrared analysis of 1, 2, and 4 have been reported previously, their crystal structures were elucidated for the first time here. In addition, the crystal structures of LFQM-116 and LFQM-117 were also determined by single crystal X-ray diffraction. The pseudo-translational symmetry found in LFQM-116 and the isomorphism between LFQM-115 and LFQM-117 are discussed. The complexes were prepared from a reaction of copper(II) nitrate trihydrate and the respective ligand in a (1:2) molar ratio in methanol (for 1 and 2) or THF (for 3 and 4) with addition of NaOH. Furthermore, crystallographic studies show that each copper(II) exhibits a square planar geometry, coordinated by four oxygens of two ligands. The nature and crystal packing of the intermolecular interactions are discussed. Compounds 2 and 3 are isomorphic crystals and all structures have the same supramolecular synthon.     

Nickel(II) and copper(II) complexes with humic acid anions and their derivatives

Complexation of Ni(II) and Cu(II) in aqueous solutions with anions of humic acids, extracted from naturally oxidized coal, and with their hydroxymethyl derivatives is studied spectrophotometrically and potentiometrically. The complexation stoichiometry and the stability constants of the complexes are determined.     

Cu(II) coordination chemistry of patellamide derivatives: possible biological functions of cyclic pseudopeptides

Two synthetic derivatives of the naturally occurring cyclic pseudooctapeptides patellamide A-F and ascidiacyclamide, that is, H(4)pat(2), H(4)pat(3), as well as their Cu(II) complexes are described. These cyclic peptide derivatives differ from the naturally occurring macrocycles by the variation of the incorporated heterocyclic donor groups and the configuration of the amino acids connecting the heterocycles. The exchange of the oxazoline and thiazole groups by dimethylimidazoles or methyloxazoles leads to more rigid macrocycles, and the changes in the configuration of the side chains leads to significant differences in the folding of the cyclic peptides. These variations allow a detailed study of the various possible structural changes on the chemistry of the Cu(II) complexes formed. The coordination of Cu(II) with these macrocyclic species was monitored by high-resolution electrospray mass spectrometry (ESI-MS), spectrophotometric (UV/Vis) and circular dichroic (CD) titrations, and electron paramagnetic resonance (EPR) spectroscopy. Density functional theory (DFT) calculations and molecular mechanics (MM) simulations have been used to model the structures of the Cu(II) complexes and provide a detailed understanding of their geometric preferences and conformational flexibility. This is related to the Cu(II) coordination chemistry and the reactivity of the dinuclear Cu(II) complexes towards CO(2) fixation. The variation observed between the natural and various synthetic peptide systems enables conclusions about structure-reactivity correlations, and our results also provide information on why nature might have chosen oxazolines and thiazoles as incorporated heterocycles.     

Magnetic and structural properties of trans-bis ( -isoleucine) copper(II)

A magnetic and structural characterization of single crystals of the copper derivative of the amino acid -isoleucine, Cu[NH₂(CH)₂CH₂(CH₃)₂CO₂]₂, was performed by EPR and X-ray diffraction techniques. The complex crystallizes in the orthorhombic space group Aba2, with a = 11.165(3) Å, b = 11.111(3) Å, c = 25.985(6) Å, and Z = 8. The copper ions occupy sites of point symmetry C₂. The position and peak-to-peak linewidth of the single EPR line observed were measured at 9.7 GHz and 293 K in three perpendicular planes of the sample. The gyromagnetic tensor has near axial symmetry around , with a small anisotropy in the perpendicular plane, in agreement with the orthorhombic symmetry indicated by the crystallographic results. The principal values of are g₁ = 2.0607(5), g₂ = 2.0616(5), and g₃ = 2.2619(3), with principal directions parallel to the crystal axes. The observed angular variation of the linewidth suggests a layered arrangement of the copper ions.     

Synthesis and thermodynamic properties of novel tripod ligands and their cobalt(II), nickel(II), copper(II) and zinc(II) complexes

Three novel compounds, based on the 1,3,5-benzene core with C₃-symmetry, have been prepared and characterized by elemental analysis, i.r. and ¹H-n.m.r. Thermodynamic properties of the ligands and their Co^II, Ni^II, Cu^II, and Zn^II metal complexes have been investigated and the corresponding stability constants obtained at 25.0 ± 0.1 °C and with I = 0.1 mol dm^–3 in KNO₃ by potentiometric titration. A linear free energy relationship exists between the stability constants of complexes and the protonation constants of ligands in the ternary system of the Cu^II-5-substituted phenanthroline-tripod ligand complexes.     

Synthesis, structure, magnetism, and spectroscopic properties of heterobinuclear copper(II)-zinc(II) complexes and their copper(II)-copper(II) analogues in asymmetric ligand environments

Heterobinuclear copper(II)-zinc(II) complexes and their homobinuclear dicopper(II) counterparts (1-4) of two asymmetric ligands (H2L1 and H2L2), based on 2-aminocyclopent-1-ene-1-dithiocarboxylate, are reported. The ligands are capable of providing both donor set and coordination number asymmetry in tandem. Metal centers in these complexes are connected by a micro-alkoxo and a bridging pyrazolate moiety, as confirmed by X-ray structure analyses of 1, 3, and 4. The Cu(1) site in the dicopper complex (1) is square planar and so are the copper sites in the Cu-Zn complexes 3 and 4. The pentacoordinated Zn sites in the latter complexes have distorted TBP geometry (tau = 0.74), while the corresponding Cu site in 1 has a highly distorted square pyramidal structure (tau = 0.54). The Cu...Zn separations in 3 and 4 are 3.3782 and 3.3403 angstroms, respectively, while the Cu...Cu distance in 1 is 3.3687 angstroms. The dicopper complexes are EPR silent at 77 K, in which the copper(II) centers are coupled by strong antiferromagnetic coupling (J = ca. -290 cm(-1)) as confirmed by variable-temperature (4-300 K) magnetic measurements. These compounds (1 and 2) undergo two one-electron reductions and a single step two-electron oxidation at ca. -0.26, -1.40, and 1.0 V vs Ag/AgCl reference, respectively, as indicated by cyclic and differential pulse voltammetry done at subambient temperatures. EPR spectra of 3 and 4 display axial anisotropy at 77 K with the gperpendicular region being split into multiple lines due to N-superhyperfine coupling (AN = 15.3 x 10(-4) cm(-1)). The observed trend in the spin-Hamiltonian parameters, gparallel > gperpendicular > 2.04 and |Aperpendicular| < |Aparallel| approximately (120-150) x 10(-4) cm(-1), indicates a d(x2-y2)-based ground state with tetragonal site symmetry for the Cu(II) center in these molecules.     

Synthesis and structures of copper(II) and cadmium(II) compounds based on pyridazine derivative ligands

The two new compounds [Cu(HODA)₂(H₂O)₂] · 3H₂O (I) and [Cd(HODA)₂(H₂O)₃] (II) (HODA = 6-oxo-1,6-dihydropyridazine-4-carboxylic acid) based on pyridazine derivation ligands have been synthesized and characterized by elemental analysis, infrared spectrum and X-ray single crystal diffraction. X-ray analysis shows that in compound I, Cu²⁺ ion is four-coordinated with a plane square geometry while Cu²⁺ ion in compound II is seven-coordinated with a distorted pentagonal bipyramid geometry. Both of the two units are all connected as 3D supramolecular structures by the intermolecular hydrogen bonds. Moreover, thermal gravimetric analysis of two compounds has been also investigated.     

Synthesis and characterization of copper(II), nickel(II) and cobalt(II) complexes with novel thiourea derivatives

A novel series of thiourea derivatives, namely, N,N-diphenyl-N-(4-phenyl-benzoyl)thiourea (HL¹), N,N-diphenyl-N-(4-chloro-benzoyl)thiourea (HL²) and N,N-di-n-propyl-N-(4-chloro-benzoyl)thiourea (HL³), and its metal complexes has been prepared and characterised by elemental analysis, i.r. spectroscopy, ¹H-n.m.r. spectroscopy, mass spectrometry and single crystal X-ray diffraction. The ligand coordinates to Ni^II, Cu^II and Co^II in a bidentate manner yielding essentially neutral complexes of the type cis-[ML₂]. N.m.r. spectra and single crystal X-ray diffraction analysis revealed the presence of a distorted tetrahedral coordination ML₂ complex.     

Synthesis,characterization, electrochemical behavior and antioxidant activity of new copper(II) coordination compounds with curcumin derivatives

Five new copper(II) coordination compounds were prepared by template synthesis, using curcumin, 2-hydrazinobenzothiazole and metal salt (copper chloride, bromide, acetate and nitrate) in 1:2:1 and 1:2:2 molar ratio. The complexes were characterized by elemental and thermogravimetric analysis, IR, UV–Vis and mass spectroscopic methods and cyclic voltammetric studies. On the basis of physico-chemical measurements the following formulae have been assigned to the complexes: [Cu(H₂L)(H₂O)₂]Cl₂·H₂O, [CuL]·H₂O, [Cu(H₂L)(H₂O)Br]Br·5H₂O, [Cu₂L(H₂O)₄](NO₃)₂·2H₂O and [Cu₂(H₂L)(NO₃)₄]·H₂O, where H₂L is the hydrazone ligand formed in the reaction conditions. Metal complexes were tested for antioxidant activity by photochemiluminescence and this activity was quantified by comparison with TROLOX®, as standard. The results show that all complexes are more potent antioxidant agents than curcumin.     

Deconvoluted Fourier-transform LNT-IR study of coordination copper(II) compounds with dextran derivatives

Deconvoluted Fourier-transform IR spectra, recorded at room and liquid nitrogen temperature, of polysaccharide dextran and its coordination compounds with the copper(II) ion were analyzed in order to find the most specific spectral peculiarities. This allows one to obtain information about the structure and conformation of these polymer compounds. Different influences on the system of intra-and intermolecular interactions were exhibited by analogs recrystallized from D₂O. The changes in intensity and width of the IR bands in the region 1450–1050 cm⁻¹ were related to changes in conformation and short-range interactions of the dextran. In the synthesized copper(II)-dextran complexes, the presence of water molecules was confirmed. The results of the FTIR spectroscopy study allowed one to suggest a predominant crystalline form of the copper(II)-dextran complexes. The text was submitted by the authors in English.     

Synthesis and mesomorphic properties of naphth-2-yl 2-pyridylmethyl ketones and their copper (II) complexes

The synthesis, characterization and mesomorphic properties of a homologous series of 6-alkoxy naphth-2-yl 2-pyridylmethyl ketones and their copper(II) complexes are reported. All the ligands and their copper complexes, with exception of the lowest homologues, exhibit enantiotropic mesophases. According to textural observations, the ligands display nematic and smectic transitions depending on the length of the alkoxy chain on the pyridine moiety, while the mesogenic complexes show exclusively smectic transitions. In comparison with the phenyl analogues, stabilization of the mesophase and a greater tendency to smectic ordering through incorporation of the naphthyl group into the molecules is confirmed.     

Inorganic-metalorganic hybrids based on copper(II)-monosubstituted Keggin polyanions and dinuclear copper(II)-oxalate complexes. Synthesis, X-ray structural characterization, and magnetic properties

Reaction of in situ generated copper(II)-monosubstituted Keggin polyoxometalates and copper(II)-bipyridine-oxalate complexes in the corresponding alkaline acetate buffer led to the formation of hybrid metal organic-inorganic compounds K(2)[{SiW(11)O(39)Cu(H(2)O)}{Cu(2)(bpy)(2)(H(2)O)(2)(mu-ox)}(2)].14H(2)O (1), K(14)[{SiW(11)O(39)Cu(H(2)O)}{Cu(2)(bpy)(2)(mu-ox)}](2)[SiW(11)O(39)Cu(H(2)O)].55H(2)O (2), (NH(4))(4)[{SiW(11)O(39)Cu(H(2)O)}{Cu(2)(bpy)(2)(mu-ox)}].10H(2)O (3), and Rb(4)[{SiW(11)O(39)Cu(H(2)O)}{Cu(2)(bpy)(2)(mu-ox)}].10H(2)O (4). Their structures have been established by single-crystal X-ray diffraction. The main structural feature of these compounds is the presence of copper(II)-monosubstituted alpha-Keggin polyoxoanions as inorganic building blocks, on which the mu-oxalatodicopper metalorganic blocks are supported. Compound 1contains the discrete hybrid polyanion [{SiW(11)O(39)Cu(H(2)O)}{Cu(2)(bpy)(2)(H(2)O)(2)(mu-ox)}(2)](2)(-), whereas the polymeric hybrid polyanion [{SiW(11)O(39)Cu(H(2)O)}{Cu(2)(bpy)(2)(mu-ox)}(2)](n)(4)(n)(-) gives a monodimensional character to compounds 2-4. Magnetic and EPR results are discussed with respect to the crystal structure of the compounds. DFT calculations on both the [Cu(2)(bpy)(2)(H(2)O)(4)(mu-ox)](2+) cationic complex and the metalorganic blocks have been performed in order to determine the optimized geometry and the magnetic coupling constants, respectively.     

Synthesis, spectra and biomimetic properties of copper(II)-copper(II) and copper(II)-zinc(II) binuclear complexes with CuN5 chromophores

X-band electron spin resonance (ESR) and UV-vis spectra of a homobinuclear [(Bipy)2Cu-E-Im-Cu(Bipy)2](BF4)3 and a heterobinuclear [(Bipy)2Cu-E-Im-Zn(Bipy)2](BF4)3 complexes, E-Im=2-ethylimidazolate ion have been described as possible models for superoxide dismutase (SOD). Magnetic moment and ESR spectral measurements of the homobinuclear complex have shown an antiferromagnetic exchange interaction. From pH-dependent ESR and UV-vis spectral measurements studies, these complexes have been found to be stable over 8.5-10.5 pH range. These complexes catalyze the dismutation of superoxide (O2-) at biological pH. All the observations indicate that these complexes act as good possible models for superoxide dismutase.     

Synthesis,spectral characterization,anticancer and antibacterial studies of cyclodiphosph(V)azane derivatives and their copper(II) complexes

The new cyclodiphosph(V)azane derivatives (1,3-dimethyl-2,4-dioxo-2',4'-bis(2,4-bis(dimethylaminopropylimino)cyclodiphosph(V)azane (H₂L¹) (1,3-dimethyl-2,4-dioxo-2',4'-bis(2,4-bis(dimethylaminoethylimino)cyclodiphosph(V)azane (H₂L²) and (1,3-dimethyl-2,4-dioxo-2'-(dimethylaminoethylimino)-4'-(dimethylaminopropyl-imino)cyclodiphosph(V)azane (H₂L³) containing four active coordination centers (NNNN) and their Cu(II) complexes have been synthesized and characterized by elemental analyses, spectroscopic methods, molar conductance as well as thermal and magnetic measurements. The UV–Vis and mass spectra of the ligands and their Cu(II) complexes were also recorded. The copper(II) complexes were found to have magnetic moments of 1.58–1.69 B. M. corresponding to one unpaired electron. The possible geometries of the complexes were assigned on the basis of EPR, electronic, and infrared spectral studies. The absence of water molecules in all complexes was supported by thermal studies. All the thermal decomposition processes ended with the formation of CuO. The kinetic and thermodynamic parameters have been calculated. The ligand (H₂L³) and its Cu(II) complexes were screened for their anticancer studies against human breast cancer cell lines MCF-7 and minimum inhibitory concentration was calculated. The screening was extended to the antibacterial activity using Kirby–Bauer single disk susceptibility test for all compounds.