Synthesis,magnetic properties,DNA binding and cleavage activity of a new oxalato bridged copper(II) complex

A novel oxalato‐bridged copper(II) complex has been prepared and structurally characterized: [Cu(bpa)(μ‐C₂O₄)].H₂O (bpa = bis(2‐pyridylmethyl) amine). In the complex, the copper ion is linked in an unusual μ_1,2,3‐C₂O₄^2? bridging mode, generating one‐dimensional zigzag chain disposition. Variable‐temperature magnetic susceptibility studies (2–300 K) reveal a weak ferromagnetic coupling, J = 0.63 cm^?1, between the copper ions. The interaction of the complex with CT‐DNA has been studied using UV–visible absorption and emission spectral methods, and the binding constant of the complex with CT‐DNA is K_app = 9 × 10⁴ m ^?1, which indicates that the interaction of the complex with DNA is a moderate intercalative mode. Furthermore, the complex cleaves supercoiled plasmid DNA efficiently in the presence of hydrogen peroxide. The mechanistic investigations suggest that the hydroxyl radical and singlet oxygen are involved in the DNA degradation. Copyright © 2012 John Wiley & Sons, Ltd.     

A new two-dimensional polymeric copper(II) complex bridged both by oxamidate and azide groups: synthesis,structure and DNA binding properties

A new two-dimensional polymeric copper(II) complex, [Cu₂(heae)(N₃)₂] _n , where heae stands for the dianion of N,N′-bis(N-hydroxyethylaminoethyl)oxamide, has been synthesized and characterized by elemental analysis, molar conductivity measurement, IR, electronic spectral studies and single-crystal X-ray diffraction. The compound crystallizes in the monoclinic system, P2₁/c space group with crystallographic data: a = 9.1588(18) Å, b = 6.6238(13) Å, c = 14.602(3) Å and Z = 2. The X-ray analysis reveals a two-dimensional copper(II) polymeric coordination network constructed by bis-tridentate chelated [Cu(trans-heae)Cu]²⁺ building blocks and end-on azido ligands. The environment around the copper(II) atom can be described as a square-based pyramid. The azido bridge is very asymmetric with one Cu–N bond distance short and the other long. The Cu ··· Cu separations through μ-trans-oxamidate and μ-azido bridges are 5.2996(13) Å and 4.2464(7) Å, respectively. The copper(II) complex is a polymer in the solid state, whereas in solution it exists as discrete neutral binuclear copper(II) species. Coordination mode of the azide in solution is proved by electronic spectra. The DNA-binding properties of the binuclear copper(II) species were investigated by emission spectral and electrochemical techniques, indicating the binuclear copper(II) complex binds to HS-DNA via a groove mode.     

Crystal structure of new melamine bridged polymeric complex of copper(II)

The new co-crystal copper(II) melamine complex poly[bis(μ-methacrylato)μ-(1,3,5-triazine-2,4,6-triamine)], C₁₉H₂₆Cu₂N₆O₈ (1) crystallizes in the triclinic P-1 space group with a = 8.9670(2) Å, b = 9.4108(2) Å, c = 15.4476(3) Å, α = 96.6090(10)°, β = 100.6270(9)°, γ = 95.5950(10)°. Each Cu(II) exhibits a pseudooctahedral geometry. Four coplanar carboxylate oxygen atoms coordinated to the Cu(II) ion define the basal plane, whereas the apical position is occupied by one nitrogen atom from the melamine ligand. Here, the carboxylato-bridged two dinuclear copper(II) complexes are linked through melamine giving a 1D alternating chain. The structure of 1 consists of a two-dimensional supramolecular layer constructed by intermolecular N-H...N hydrogen bonds of the melamine ligands from adjacent one-dimensional [Cu₂(C₄H₅O₂)₄(C₃H₆N₆)] chains.     

Synthesis,structure, DNA binding and cleavage ability of a new copper ciprofloxacin complex

The structure of 1 consists of [Cu(HCp)(phen)(H₂O)]²⁺ (HCp is ciprofloxacin and phen is 1,10-phenanthroline), two acetates, and four free water molecules. In each cation, copper displays a distorted square pyramid, coordinated to ring 3-carboxylate and 4-oxo oxygen from HCp, two nitrogens from phen, and one water molecule. There are five water molecules in each discrete complex with one coordinated to Cu center, and the other four linked to each other by intermolecular hydrogen bonds. Two uncoordinated acetates make the compound neutral. The complex exhibits higher DNA binding compared to HCp at the same conditions by fluorescence and viscosity measurements. Combining its structure with the DNA-binding result, the binding mechanism may be explained by intercalation. Moreover, 1 shows significant cleavage of DNA in the presence of a reducing agent, such as ascorbate by gel electrophoresis using supercoiled pBR322 DNA in Tris-HCl buffer (pH 7.4). The complex also has a higher activity against Gram-positive bacteria Staphylococcus aureus and Gram-negative bacteria Klebsiella pneumoniae than HCp.     

Binuclear copper(II) complex with 2-imidazolylbenzothiazole and bridged chloride ligands

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Synthesis and structure of copper(II) complex with comenic acid

Russian Journal of General Chemistry -     

Synthesis,crystal structure,and DNA binding of a new oxalato-bridged binuclear zinc(II) complex

A new binuclear zinc(II) complex bridged by μ-oxalate, and end-capped with 2,2′-bipyridine (bpy), [Zn₂(ox)(bpy)₄](ClO₄)₂ · H₂O, has been synthesized and characterized by elemental analyses, molar conductance, IR, and electronic spectra and single-crystal X-ray diffraction. The single-crystal X-ray analysis reveals that the [Zn₂(ox)(bpy)₄]²⁺ cation has two zinc(II) centers bridged by a planar bis(bidentate) oxalate group with Zn···Zn distance of 5.482(3) Å; each zinc(II) is in a distorted octahedral environment. The crystal structure is stabilized by non-classical C–H···O hydrogen bonds and π–π stacking interactions to form a 3-D supramolecular structure. The interaction of the complex with calf-thymus DNA (CT-DNA) was explored by using electronic and fluorescence spectra and viscosity measurements. The results reveal that the complex intercalates with CT-DNA with intrinsic binding constant of 4.1 × 10⁴ M^?1.     

Synthesis and crystal structure of a new copper(II) binuclear complex bridged by the reduced derivative of a nitronyl nitroxide biradical

A new copper(II) binuclear complex, [Cu(hfac)₂]₂(IMH)₂Ph(OMe)₂ ((IMH)₂Ph(OMe)₂?=?2,5-dimethoxyl-1,4-bis(4′,4′,5′,5′-tetramethylimidazoline-3′-oxide)benzene, hfac?=?hexafluoroacetonate), bridged by a reduced derivative of a nitronyl nitroxide biradical has been synthesized and characterized by X-ray crystallography. The complex crystallizes in the monoclinic space group P2₁/n, with a?=?10.002(14), b?=?19.950(3), c?= 14.504(2) Å, β?=?108.842(3)° and Z?=?2. The structure refined to a final R value of 0.0644. The complex contains two copper(II) ions bridged by a reduced derivative of a nitronyl nitroxide biradical with a Cu?···?Cu separation of 8.430(2) Å.     

X-ray structure and EPR behavior of a new dimeric copper(II) complex with 4-amino-N-(5-methoxy-2-pyrimidinyl)benzenesulfonamide

A new complex, [Cu₂(sulfameter)₄]₃ · 2.5H₂O (sulfameter = 4-amino-N-(5-methoxy-2-pyrimidinyl)benzenesulfonamide), has been synthesized. Its structure has been determined by single-crystal X-ray diffraction and its spectroscopic properties (EPR, IR, Raman, UV–Vis) have been analyzed. The structure presented three different dimeric units in the unit cell and the EPR spectra, characteristic of antiferromagnetically coupled dimers, revealed two magnetically different dimeric environments.     

Synthesis and magneto-structural correlation of a new maleato bridged copper(II) coordination polymer

A one-dimensional (1-D) copper(II) coordination polymer [Cu(maleate)(2,2′-bipyridyl)] _n ·2H₂O has been synthesised. Single crystal X-ray diffraction study reveals that maleate ion bridges two adjacent copper(II) centres along the chain in a syn–anti fashion. A complete cryomagnetic investigation of the title complex correlates well with the distorted square pyramidal geometry of the central copper(II) ion and bridging nature of the maleate. A τ value of 0.26 indicates the distortion towards tbp coordination allowing the magnetic orbital to acquire some character leading to a weak antiferromagnetic interaction having J = −0.26 cm⁻¹. The complex has also been firmly established from several other instrumental techniques like Fourier transform infrared (FT-IR) and EPR spectroscopies.     

Synthesis,crystal structure and properties of a 1D copper(II) complex with 1,5,9-triazacyclododecane bridged by p -benzenebicarboxylate

A 1D complex [{[Cu₂([12]aneN₃)₂(p-paa)(H₂O)₂](ClO₄)₂}[Cu₂([12]aneN₃)₂(p-paa)₂]] _n ([12]aneN₃ = 1,5,9-triazacyclododecane, p-paa = p-benzenebicarboxylate) has been synthesized and structurally characterized. The complex contains two different binuclear copper(II) moieties. One part includes a binuclear copper(II) unit and non-coordinated perchlorate anions. A neutral binuclear copper(II) part which forms a zigzag chain structure via the bridging p-paa ligand completes the unit-cell. Elemental analysis, IR, UV-Vis spectra and magnetic properties for the complex have also been determined. Magnetic susceptibilities in the solid state are measured over the temperature range from 77 to 300 K, showing a weak antiferromagnetic coupling with a best fit J ₁ = ?3.09 cm^?1, J ₂ = ?5.279 cm^?1, g = 2.099 and R = 1.226 × 10^?5.     

Synthesis, characterization, crystal structure and antitumor activities of a novel demethylcantharidato bridged copper(II) phenanthroline complex

A new polymeric demethylcantharidato (DCA) bridged copper(Ⅱ) phenanthroline (phen) complex ([Cu(DCA)(phen)] n ·nH2O) has been synthesized and characterized by elemental analysis, IR and electronic spectra studies, molar conductivity measurement, and single crystal X-ray diffraction. The complex crystallizes in the orthorhombic space group Pbca with crystallographic data: a = 12.4537(4), b = 9.3897(5), c = 30.1264(10), and Z = 8. In the crystal structure, the octahedral coordinated copper(Ⅱ) ions are bridged by demethylcantharidate ligands into a one-dimensional zigzag-like structure with the Cu···Cu separation of 6.1719, along with phen ligands attached to both sides of the chain alternatively. Interdigitation of the chelating phen ligands of two neighboring chains via hydrophobic interaction and van der Waals forces along ac plane forms two-dimensional polymeric bilayers with discrete water sandwich layer between the adjacent polymeric bilayers. The evaluation of the cytotoxic activity of the copper(Ⅱ) complex against HCT-8 (colorectal carcinoma), A549 (pulmonary carcinoma), HeLa (cervical cancer), HepG2 (hepatocarcinoma), BGC-823 (gastric carcinoma), and MCF-7 (breast adenocarcinoma) cell lines revealed that it is a potent cytotoxic agent, superior to Na2DCA and phen against HeLa, HepG2 and BGC-823 cells.     

Synthesis,DNA binding and oxidative cleavage studies of an asymmetric tridentate copper(II) complex

An asymmetric tridentate Cu^II complex, [Cu(ptp)Cl₂] (ptp = 3-(1,10-phenanthrolin-2-yl)-as-triazino[5,6-f]-phenanthrene), has been synthesized and characterized by elemental analysis, FAB-MS, i.r. and u.v.–vis. spectra. The DNA binding behavior of the complex has been examined by fluorescence quenching, cyclic voltammetric and viscosity measurements. The results suggest that [Cu(ptp)Cl₂] binds to DNA in the intercalative mode. This complex is also found to produce cleavage of pBR 322 DNA in the presence of reducing agents such as ascorbate/H₂O₂, and the hydroxyl radical (OH^•) is suggested to be the reactive species responsible for the cleavage.     

DNA and RNA binding studies on a novel bromo-bridged dimeric copper(II) complex stabilized from a Schiff base ligand

Abstract

A novel red copper(II) compound, bis(μ-bromo)bis(2-(benzothiazol-2-yl-hydrazono)-1,2-diphenyl-ethanone)-dicopper(II) (1), has been fostered by equimolar reaction of a Schiff-base ligand, 2-(benzothiazol-2-yl-hydrazono)-1,2-diphenyl-ethanone (LH), with copper(II) bromide in satisfactory yield. 1 has thoroughly been characterized by C, H and N elemental analyses, FT-IR and UV-vis (both in solid state and in solution) spectroscopies, and room-temperature magnetic susceptibility and conductivity measurements. Dimeric 1 bears symmetric rare bromo-bridges in its crystal structure. 1 retains its solid-state identity even in a protic solvent like methanol. 1 in methanol displays two-step one-electron redox response. Theoretical calculations based on DFT were executed to probe the electronic structure of 1 and to augment its color. DNA- and RNA-binding aspects of both LH and 1 have been explored. Thermodynamic binding parameters have been determined. LH is a major-groove binder to DNA, while 1 manifests itself as a minor-groove binder. This binding has been corroborated through molecular docking. Nucleic acid binding aspect of such type of rare bromo-bridged red copper(II) dimer is unprecedented.     

A complex of cadmium(II) iodide with 4-cyanopyridine: Synthesis,crystal structure,and luminescent properties

The complex [CdI₂(4-CNPy)₂] (I) was obtained by a reaction of CdI₂ with 4-cyanopyridine (4-CNPy, C₆H₄N₂) and structurally characterized (CIF file CCDC no. 983377). The crystals of complex I are monoclinic, space group C2, a = 24.698(5) Å, b = 4.127(1) Å, c = 7.597(2) Å, β = 96.05(1)°, V = 770.0(3) ų, ρ_calcd = 2.477 g/cm³, Z = 2. In structure I, iodine atoms serve to unite complex molecules into the polymer chains [CdI₂(4-CNPy)₂]_∞ along the direction [010]. The Cd(1) atom lying on a twofold axis has a slightly distorted octahedral environment made up of four bridging iodine atoms and two nitrogen atoms of two ligands 4-CNPy (Cd-I_av, 2.947(2) and Cd-N(1), 2.410(6) Å). Within each chain, cadmium atoms are spaced apart at 4.13 Å. Complex I exhibits photoluminescence.     

Synthesis,characterization and in vitro DNA binding studies of a new copper(II) complex containing antioxidant ferulic acid

A mononuclear Cu(II) complex, [Cu(FA)₂(NO₃)₂], in which FA is ferulic acid ((E)-3-(4-hydroxy-3-methoxy-phenyl)prop-2-enoic acid), was synthesized and characterized by spectroscopic methods. The main structures of the ligand and its complexes with Cu²⁺ were optimized by QM calculations. The calculations on the structures of the [Cu(FA)₂(NO₃)₂] complexes forms and the intercalating with DNA profile were undertaken by UHF/PM6 and MMFF94 methods, respectively. In vitro studies (UV-vis spectroscopy, emission titration, circular dichroism techniques, and viscometry) under physiological conditions (Tris-HCl buffer solutions, pH 7.4) showed that the complex interacts with calf-thymus DNA (ct-DNA) via an intercalative binding mode. The thermodynamic parameters, enthalpy change (ΔH), and entropy change (ΔS) showed that the acting forces between Cu(II) complex and ct-DNA mainly included van der Waals interactions and hydrogen bonds. Methylene blue (MB) displacement studies revealed that Cu(II) complex can substitute MB probe in the MB-DNA complex which was indicative of intercalative binding. The theoretical data confirm the experimental results with respect to the mechanism of binding.