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The title compound, [Cu2(C7H4NO4)4(C3H7NO)2]·(C3H7NO)2, is a binuclear copper(II) complex located on an inversion center midway between the two copper(II) cations. The asymmetric unit consists of one CuII cation, two 3-nitrobenzoato ligands, and two dimethylformamide (DMF) molecules, one of which coordinates to the CuII cation and one is a solvate molecule. The carboxylate groups of the ligands bridge two CuII cations with a Cu—Cu distance of 2.6554 (6) Å, completing a distorted octahedral O5Cu coordination environment. The dihedral angles between the carboxylate and the aromatic ring planes of the two independent ligands are different from one another, viz. 5.2 (3) and 23.9 (3)°. The three-dimensional structure is consolidated by weak C—H...O interactions and stabilized by π–π stacking interactions between the aromatic rings. The complex and the free ligand were further characterized by Fourier-transform infrared spectroscopy (FT–IR), and the energies of the frontier molecular orbitals of the complex were determined by DFT calculations at the B3LYP/def2-TZVP level of theory.

The title compound, [Cu2(C7H4NO4)4(C3H7NO)2]·(C3H7NO)2, is a binuclear copper(II) complex located on an inversion center midway between the two copper(II) cations. The asymmetric unit consists of one CuII cation, two 3-nitrobenzoato ligands, and two dimethylformamide (DMF) molecules, one of which coordinates to the CuII cation and one is a solvate molecule. The carboxylate groups of the ligands bridge two CuII cations with a Cu--Cu distance of 2.6554 (6) A °, completing a distorted octahedral O5Cu coordination environment. The dihedral angles between the carboxylate and the aromatic ring planes of the two independent ligands are different from one another, viz. 5.2 (3) and 23.9 (3)C. The three-dimensional structure is consolidated by weak C--H...O interactions and stabilized by ... stacking interactions between the aromatic rings. The complex and the free ligand were further characterized by Fourier-transform infrared spectroscopy (FT-IR), and the energies of the frontier molecular orbitals of the complex were determined by DFT calculations at the B3LYP/def2-TZVP level of theory. [ABSTRACT FROM AUTHOR]

The asymmetric unit of the binuclear title compound, [Cu2(C8H7O3)4(H2O)2], comprises two halves of diaquatetrakis(μ-3-methoxybenzoato-κ2O1:O1′)dicopper(II) units. The paddle-wheel structure of each complex is completed by application of inversion symmetry, with the inversion centre situated at the midpoint between two CuII atoms in each dimer. The two CuII atoms of each centrosymmetric dimer are bridged by four 3-methoxybenzoate anions resulting in Cu...Cu separations of 2.5961 (11) and 2.6060 (12) Å, respectively. The square-pyramidal coordination sphere of each CuII atom is completed by an apical water molecule. Intermolecular O—H...O hydrogen bonds of weak nature link the complexes into layers parallel to (100). The three-dimensional network structure is accomplished by C—H...O hydrogen bonds interlinking adjacent layers.

• Synthesis and characterisation of an unprecedented Cu(II) complex of Schiff base derived from taurine and 2‑hydroxy-4-methoxybenzaldehyde. • SCXRD has been used to elucidate crystal structure. • Thermochemistry, atomic electrostatic potentials, and electronic properties were studied using DFT. • Interpretation of Hirshfeld analyses provides information concerning crystal packing and internuclear interactions. • Cu(II) complex can alter the biological capabilities as this trace metal is involved in neurotransmitter synthesis and antioxidant defence. Binuclear Cu(II) complex derived from taurine and 2‑hydroxy-4-methoxybenzaldehyde adduct was synthesised and characterised by X-ray crystallography, spectroscopic, Hirshfeld surface and DFT studies. The complex crystallises in monoclinic system with I 2/a space group. A theoretical study of the Cu (II) complex is performed with unrestricted density functional method at the level of B3LYP/ LANL2DZ/6–311 G (d, p) and a comparison between the experimental and simulated results were conducted. As predicted by the experiment, the computed results support distorted pyramidal geometry at metal centre. Non-covalent interactions primarily H-bonding and π-π stacking close contacts were observed at the intramolecular and intermolecular levels of the complex. An analysis of the FMO parameters reveals less reactivity and stability of complex. A high HOMO energy value and interatomic charge transfer has taken place with the Schiff base ligand. Furthermore, MEP used for predicting reactive sites clearly shows this complex is void of electrophilic reaction site. This complex has been subjected to NBO analysis to determine its hyperconjugation and therefore stability. The NBO analysis revealed the delocalization of charge within the molecule. Based on Hirshfeld surface analysis, there is evidence for a wide range of interactions and a significant contribution from several non-covalent interactions to crystal packing. [Display omitted] [ABSTRACT FROM AUTHOR]

Copper, nickel, and cobalt complexes of the N,N,S-tridentate tosylamino-functionalized mercaptopyrazole Schiff base were obtained by an electrochemical method. The structure and composition of the metal chelates were characterized by C, H, N elemental analysis data and IR and H NMR spectroscopy. More data on the structures of the complexes were obtained by magnetochemical and X-ray absorption spectroscopy measurements. The mononuclear structure of the copper(II) complex was confirmed by X-ray diffraction (CIF file CCDC no. 1473320). [ABSTRACT FROM AUTHOR]

Two types of binuclear copper complexes [LCuN3]2 and [LCuNO3]2.of bidentate ligand ‐ diphenyl‐(1‐propylbenzimidazol‐2‐yl)methanol (HL) in the 4:1 ratio were synthesized. The crystal structure of copper complexes shows a centrosymmetric dimeric binuclear complex with two Cu2+ cations bridged by two oxygen atoms from two organic ligands. In the complexes, a very strong antiferromagnetic exchange interaction between copper atoms is observed. [ABSTRACT FROM AUTHOR]

A new organic–inorganic hybrid silicotungstate [Cu2(phen)2Cl(H2O)(OH)]2[α-SiW12O40]·8 H2O (1) (phen = 1,10-phenanthroline) with supporting dinuclear copper complexes has been hydrothermally synthesized and structurally characterized by elemental analyses, IR spectroscopy, and single-crystal X-ray diffraction. The molecular unit of 1 consists of two pendant coordination cations [Cu2(phen)2Cl(H2O)(OH)]2+and one saturated Keggin-type silicotungstate polyoxoanion [α-SiW12O40]4−and eight lattice water molecules. The most intriguing feature is that each bi-copper cation [Cu2(phen)2(μ2-Cl)(H2O)(OH)]2+is constructed from two [Cu(phen)]2+cations linked by one μ2-Cl and one hydroxyl bridges. Magnetic measurements indicate that 1 demonstrates the ferromagnetic exchange interactions within CuIIcenters. [ABSTRACT FROM PUBLISHER]

Abstract: Two new, binuclear copper(II) hydrazone complexes have been synthesized and characterized by various physico-chemical techniques including single crystal X-ray diffraction. Interaction of these complexes with nucleotide and protein were analyzed by in vitro biochemical and electrochemical analysis. Both the complexes exhibited intercalative mode of binding with DNA. Further, gel electrophoresis assay demonstrated the ability of the complexes to cleave the supercoiled pBR322 plasmid DNA to nicked circular DNA form. Cytotoxicity of the complexes performed against a panel of cancer cell lines and a normal cell line proved that these complexes are potentially cytotoxic against the cancerous cell lines, particularly with IC50 as low as 0.7 μM against HeLa cell line. [Copyright &y& Elsevier]

Tetra–μ–[N-phenylanthranilato](O,O′)–bis[2-amino-4-methyl) pyridine copper(II)] (bisdichloromethane solvate and unsolvate) in one crystalline contains two independent binuclears, one of which is unsolvate and the other one is dichloromethane solvate. The phenyl ring planes in the asymmetric units were not parallel to each other [44.47(14)° and 52.50(13)° for unsolvate unit, 53.30(14)° and 49.59(13)° for solvate unit] and the distance between the two centers of phenyl rings was measured as 5.064 Å (for Cg2-Cg3), 5.005 Å (for Cg4-Cg5), 5.048 Å (for Cg7-Cg8), and 5.088 Å (for Cg9-Cg10) for NPA ligands. The complex molecules showed three dimensional supramolecular networks by O–H···O, C–H···O, C–H···π, and π···π interactions. [ABSTRACT FROM AUTHOR]

Abstract: A binuclear acylhydrazine bridged Cu(II) complex, [Cu2(L)(NO3)3(H2O)] (1), and an anti-orthogonal binuclear oxovanadium(V) complex, [V2O4(L)2] (2), have been synthesized and characterized spectroscopically and crystallographically. The ligand HL has two potentially bridging functional groups (μ-O, μ-N–N) and consequently can exist in the following coordination conformers: (a) metal centers bridged by μ-O, (b) metal centers bridged by μ-N–N. A rare acylhydrazine bridged (a) type configuration exists in the dinuclear Cu(II) complex 1. The bridging ligand mediates a strong antiferromagnetic coupling (J =−99cm−1). The exchange pathway parameters have also been evaluated from density functional theoretical calculations to corroborate the bridging signatures with experimental findings (J =−93.96cm−1). Molecule 2 has a centrosymmetric structure with each vanadium center having a distorted octahedral geometry. It shows a one step irreversible reduction at +0.43V. The bond angles, bond lengths and torsion angles in 2 are correlated with DFT. [Copyright &y& Elsevier]

The complexes, tetra-μ-[2-(phenylamino)benzoato](O,O′)-bis[(ethanol)copper(II)] (1) and di-μ-[2-(phenylamino)benzoato](O,O′)-bis[(hydroxo)copper(II)] (2), were synthesized by the reaction of N-phenylanthranilic acid and CuCl2·2H2O in an ethanol water mixture. In complex 1, each Cu(II) atom, which is in a slightly distorted square pyramidal environment, is coordinated equatorially by four N-phenylanthranilate O-atoms and axially by the ethanol O-atoms. In complex 2, [Cu2(C6H5NHC6H4COO)2(OH)2], each Cu(II) atom, which is in tetrahedral environment, is coordinated by two N-phenylanthranilate O-atoms and hydroxo ligands. The crystal structure (monoclinic, P21/c space group) of complex 1 comprises a dinuclear [Cu2(C6H5NHC6H4COO)4(CH3CH2OH)2] species and the dimer is located on a crystallographic inversion centre. The Cu(II) ions, 2.591(2) Å apart, are bridged by the carboxylate groups of four N-phenylanthranilate ligands. The complex molecules show three-dimensional supramolecular networks by O–H···O, C–H···O and C–H···π interactions. [ABSTRACT FROM AUTHOR]

The exchange coupled site behaves as a good structural and functional model for type 3 active site in copper oxidases and is both efficient and selective catalyst for oxidation of diphenols. [Display omitted] A new copper(II) complex, [Cu 2 (L1)(µ-Cl) 2 ] 2 (C1), of the binucleating 2,6-bis((2-(4′-imidazolyl)ethyl)aminomethylidene)-4-methylphenol (HL1) with N 4 O binding sites, has been synthesized to investigate as potential structural and functional model for catecholase activity of the dicopper(II) site. It has been characterized by spectroscopic techniques and X-ray crystallography. The complex C1 exists as chlorido bridged dimer of binuclear copper(II) units, each possessing one end-off compartmental ligand (L1) with endogenous µ-phenoxido and exogenous µ-chlorido groups leading to intermetallic distance Cu1···Cu2 of 3.129 Å and Cu1-O1(phenoxo)-Cu2 angle of 107.67(10)o. Each copper(II) center has distorted octahedral geometry with bridging by chlorides in the tetranuclear dimer. The crystal system is monoclinc with space group P 2 1 / c. Magnetic measurements reveal that C1 is strongly antiferromagnetically coupled with J = − 115.663 ± 0.82547 cm−1. The catecholase activity of the complex has been evaluated by oxidation of 3,5-di(tert -butyl)catechol and 4-methyl catechol to the corresponding quinones under aerobic conditions. A kinetic treatment on the basis of the Michaelis-Menten model has been applied for the kinetic study. The complex is found to be selective for the substrates with higher V max = 8.2726x10−8 M s−1 and K m = 0.0107 M for 3,5-DTBC at 30 °C as compared to V max = 5.0371x10−8 M s−1 and K m = 0.027 M for 4-methyl catechol at 50 °C while it is found to be practically inactive for dopamine, 2,3-dihydroxy naphthalene and pyrocatechol oxidation. [ABSTRACT FROM AUTHOR]

Binuclear copper complex (2-[bis(2-aminoethyl)amino]ethanol, 4,4′-bipyridine bridged dicopper(II) complex) was grafted onto the surface of a glassy carbon electrode (GCE) using the cyclic voltammetric method in a phosphate buffer solution (PBS). The modified electrode resulted in efficient electrocatalytic activity for anodic oxidation of uric acid (UA) and ascorbic acid (AA) via a substantial decrease in anodic over-potentials for both compounds. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) using this modified electrode result in two well-resolved anodic waves for the oxidation of UA and AA in mixed solution, making possible the simultaneous determination of both compounds. Linear analytical curves were obtained in the ranges 5.0–300.0 μM and 5.0–160.0 μM for UA and AA concentrations through DPV methods, respectively. The detection limits were 2.0 μM of UA and AA. This electrode was used for UA and AA determinations in urine samples with satisfactory results. [ABSTRACT FROM AUTHOR]

The reaction of Cu(NO3)2 with salicylidene-[1-(t-butyl)-5-methyl-1H-pyrazole]-formohydrazine (Hsal-pfh, 1) gives a binuclear Cu(II) complex [Cu2(sal-pfh)2(NO3)2] (2). The structure of the ligand was characterized by IR, EA, 1H NMR spectroscopy. The binuclear Cu complex was determined by X-ray crystallography and thermal analysis. The two Cu(II) ions are bridged by two O atoms and each copper ion is surrounded by an asymmetric sal-pfh chromophore and a [image omitted] group. The coordination around each copper can be best described as a distorted square-pyramidal geometry. The electrochemical experimental results indicate that 2 can bind to DNA with good stability. [ABSTRACT FROM AUTHOR]

A novel modified glassy carbon electrode (GCE) with a binuclear copper complex was fabricated using a cyclic voltammetric method in phosphate buffer solution. This modified electrode shows very efficient electrocatalytic activity for anodic oxidation of both dopamine (DA) and ascorbic acid (AA) via substantial decrease in anodic overpotentials for both compounds. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) using this modified electrode show two well-resolved anodic waves for the oxidation of DA and AA in mixed solution, which makes it possible for simultaneous determination of both compounds. Linear analytical curves were obtained in the ranges 2.0–120.0 μM and 5.0–160.0 μM for DA and AA concentrations by using DPV methods, respectively. The detection limits were 1.4 × 10−6 M of DA and 2.8 × 10−6 M of AA. This electrode was used for AA and DA determinations in medicine and foodstuff samples with satisfactory results. [ABSTRACT FROM AUTHOR]

A novel binuclear complex [Cu2 (PPh3)2 (µ-OOCH)](ClO4)(II)was synthesized via the interaction of carbon dioxide with [Cu(PPh3)2(BH4)] (I) in the presence of PPh3 and NBu4 (ClO4). It was characterized by elemental analysis and spectroscopic methods as well as by single-crystal X-ray diffraction. Crystals are monoclinic, space group C2/c , with a = 25.911(5), b = 13.6361(3), c = 26.929(5)Å, β = 90.21(3), V = 9323.1(3)Å3, Z = 8 and Dc = 1.314 g cm-3. The formate ligand of II in the solid state displays a near-perfect linear coordination mode as CO2 and serves as a bridge for the two Cu(PPh3)3 units with the O-C-O bond angle being 180.0(5)°. A mechanism involving carbon dioxide insertion into the Cu-H bond of [Cu(PPh3)3(BH4)] (I) for the formation of II is proposed. [ABSTRACT FROM AUTHOR]

Abstract: The search for efficient artificial nucleases is a consequence of the huge efforts towards DNA sequencing by genome projects around the world. In the present study, we describe the activity of the Cu(II)–BMXD complex (BMXD=3,6,9,17,20,23-hexaazatricyclo[23.3.1.111,15]triaconta-1(29),11(30),12,14,25,27-hexaene) as a DNA cleavage agent. The rate constant for the DNA backbone cleavage reaction at room temperature (25°C) and pH 7.0 was estimated to be 1.1×10−6 s−1, which corresponds, approximately, to a half-life (t 1/2) of one week. We demonstrated that the DNA cleavage reaction promoted by the Cu2BMXD complex may occur via an oxidative pathway through performing reactions in the presence of free-radical acceptors and comparing the activity under aerobic and anaerobic conditions. The Cu2BMXD complex reported here is established as a novel artificial nuclease. [Copyright &y& Elsevier]

A new crown ether derivative 4,7,13,16-tetrabenzyl-1,10-dioxa-4,7,13,16-tetraaza-cyclooctadecane together with its binuclear copper(II) complex have been prepared and characterized by elemental analysis, IR, NMR and UV spectra. X-ray diffraction study shows that the complex crystallizes in the monoclinic system, C2/c space group, with a=29.052(10), b=10.398(4), c=21.084(7) Å, β=128.538(5)°, V=4982(3) Å3 and Z=4. It also reveals that in the binuclear structure, each copper(II) ion is coordinated to two nitrogen atoms from the crown ether and three oxygen atoms, one from the crown ether, one as bridge from hydroxide group, and the third from the water molecule. The coordination polyhedron is a distorted trigonal bipyramid. [Copyright &y& Elsevier]

A dicopper complex of a Schiff's base, 2-[(4-methyl-pyridin-2-ylimino)-methyl]-phenol, with a bridging acetato ligand has been synthesized and characterized by single crystal XRD, EPR, magnetic susceptibility, IR, UV–Vis, CV and elemental analysis. The X-ray analysis indicates that the system belongs to the triclinic space group P1¯. One of the copper atoms in the binuclear complex adopts a square-pyramidal geometry consisting of the tridentate N-salicylidimine dianions, the neutral monodentate pyridine ligand in the basal plane and the solvent molecule in the apical position, while the other copper assumes a square-planar geometry. A seven line pattern observed at half-field in the frozen solution EPR spectrum confirms the interaction between the two copper ions. The cyclic voltametric studies point to a two-step electron transfer indicating the reduction of the two copper ions to copper(I), i.e., Cu(II)Cu(II) ↔ Cu(II)Cu(I) ↔ Cu(I)Cu(I). The molar conductance for the complex measured in methanol solvent indicates that the complex is a 1:1 electrolyte. [Copyright &y& Elsevier]

N-dealkylation in [(LCu)2(μ-O)2]2+ (L=1,4,7-tribenzyl-1,4,7-triazacyclononane) is predicted by quantum–mechanical/molecular–mechanical calculations using density functional theory to take place with the dioxocopper core in a bis(μ-oxo) geometry via a mechanism involving internal hydrogen atom transfer of an equatorially located benzylic H to an oxo oxygen atom. This step is followed by a very-low barrier hydroxyl group rebound to generate an aminal that is hydrolyzed to an aldehyde on aqueous workup. There is some polar character to the H atom-transfer transition state so that it is weakly sensitive to aromatic substitution. At 233 K, tunneling plays a significant role in the kinetics. [Copyright &y& Elsevier]