Oxidative DNA cleavage by copper ternary complexes of 1,10-phenanthroline and ethylenediamine-sulfonamide derivatives

Ternary copper(II) complexes (1–3) of 1,10-phenanthroline and ethylenediamine-R-sulfonamide derivatives (R = benzene, toluene and naphthalene rings) have been synthesized and characterized with the aid of X-ray diffraction and spectroscopic and electrochemical techniques. The crystal structures of the complexes show that the coordination polyhedron around copper(II) is distorted square planar. Both 1,10-phenanthroline and ethylenediamine-R-sulfonamide act as bidentate ligands. The three structures are stabilized by π–π stacking interactions. The interaction of the complexes with calf thymus DNA has been investigated by thermal denaturation studies which indicated that DNA was stabilized in the presence of the compounds. The increase in DNA stability induced by the complexes follows the order: 3 > 2 > 1. All three complexes were found to be very efficient agents of plasmid DNA cleavage in the presence of ascorbate as reducing agent. Mechanistic studies of the DNA cleavage process performed with radical scavengers show that the reactive oxygen species involved in the DNA damage are the hydroxyl radical, singlet oxygen-like species, the superoxide* and hydrogen peroxide.     

Thermal behaviour of complexes of antipyrine derivatives II

Parent and mixed ligand complexes of cobalt(II) and copper(II) ions with N,N-bis-(4-antipyrylmethyl)piperazine or N,N-tetra(4-antipyryl-methyl)-1,2-diaminoethane or/and imidazole as ligand and ClO ₄ ^– or SCN^– as counterion were synthesised and their thermal behaviour was investigated.This work was performed in the framework of cooperation between the Hungarian Academy of Sciences and Romanian Academy and was supported financially, in part, by the Hungarian Scientific Research Foundation (OTKA T 029554).     

Design,synthesis, characterization and antibacterial properties of copper(II) complexes with chromone‐derived compounds

A new series of six chromone‐derived compounds and their Cu(II) complexes was synthesized and characterized by their physical, spectral and analytical data The elemental analysis data of the complexes agree well with the proposed composition of the compounds, which were found to be dimeric in nature with two hydrazine molecules bridging the two copper atoms through coordination. The ligands and their Cu(II) complexes were screened for their in‐vitro antibacterial activity against four Gram‐negative (Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, Shigella flexneri) and two Gram‐positive (Bacillus subtilis, Staphylococcus aureus) bacterial strains by the agar‐well diffusion method. The ligands were found to exhibit either no or low to moderate activities against one or more of the bacterial species, whereas all the metal complexes exhibited moderate to high activities against different bacterial species. The ligands which were inactive before complexation turned active and less active ones became more active upon coordination with copper ions. Overall, the complexes 7–12 showed comparatively much higher activities than the ligands. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis,characterization and antimicrobial activity of a new macrocycle and its transition metal complexes

The semicarbazone (L¹) has been prepared by reaction of semicarbazide and glutaraldehyde (2 : 1) in distilled water and methanol (1 : 1). The reaction of semicarbazide, glutaraldehyde and diethyl oxalate in distilled water and methanol gave Schiff-base L², 1,2,4,7,9,10-hexaazacyclo-pentadeca-10,15-dien-3,5,6,8-tetraone. Complexes of first row transition metal ions Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) have also been synthesized. The ligand and its complexes were characterized by elemental analysis, molar conductance, magnetic moment measurements, IR, ¹H NMR, UV–Visible spectra and thermogravimetric analysis (TGA). Molar conductance values show that the complexes of Ni(II), Cu(II), Zn(II), Mn(II) and Co(II) are 1 : 2 electrolytes. On the basis of electronic spectral studies and molar conductance measurements an octahedral structure has been proposed for Mn(II) and Co(II) complexes, tetrahedral for Zn(II) complex and square planar for Ni(II) and Cu(II). The thermal behavior of the compounds, studied by TGA in a nitrogen atmosphere up to 800°C, reveal that the complexes have higher thermal stability than the macrocycle. All the synthesized compounds and standard drugs kanamycin (antibacterial) and miconazole (antifungal) have been screened against bacterial strains Staphylococcus areus, Escherichia coli and fungal strains Candida albicans, Aspergillus niger. The metal complexes inhibit growth of bacteria to a greater extent than the ligand.     

Complexes of substituted dipyridylpyridazines with palladium(II) and platinum(II)

Reactions of 3,6-bis(2′-pyridyl)pyridazine derivatives (n-dppn)¶ ¶For the n-dppn ligands, n stands for the size of the cyclic aliphatic ring on positions 4 and 5 of the pyridazine ring, n?=?5, 6, 8, and 12. with MX₂(PhCN)₂ (M?=?Pd, Pt; X?=?Cl,?Br) have been investigated. The new complexes cis-[PdCl₂(n-dppn)] (n?=?5,?6,?8,?12), cis-[PtCl₂(n-dppn)]?·?H₂O (n?=?5,?6), cis-[PtCl₂(8-dppn)] and cis-[PtBr₂(5-dppn)] have been characterized by elemental analyses, conductivity measurements, infrared, electronic and ¹H-NMR spectra.     

Stabilities of mixed ligand complexes of Cu(II) with ligands coordinating through O and N : ESR studies

Mixed ligand complexes of Cu(II) with 8-hydroxy-quinolinate (Hy) as one ligand and acetylacetonate (ac.ac) or salicylaldehydate (Sal) as the second ligand have been prepared in reaction mixtures of Cu(Hy)₂ + Cu(ac.ac)₂ and Cu(Hy)₂ + Cu(Sal)₂ in chloroform. Ligand hyperfine structures and the minimum ESR linewidth associated withm = − 3/2 hyperfine component have been used to detect and identify the mixed ligand complexes. The ligands in these complexes coordinate through O or N. The constantsK associated with the ligand exchange equilibriums are ~ 2 at −20°C and are close to the value expected from the empirical relation obtained in an earlier work from a study of Cu(II) complexes in which S also participates in the coordination.     

Mixed-ligand ternary complexes of potentially pentadentate but functionally tridentate Schiff base chelates

The potentially pentadentate chelate 2,6-diacetylpyridine-bis(N-methyl-S-methyldithiocarbazate) (Nmedapsme) has been synthesized and structurally characterized by X-ray diffraction. Its reactions with nickel(II) salts did not lead to pentadentate coordinated ligand complexes but ternary complexes of general formula, [Ni(Nmedapsme)(nmesme)L]X·H₂O (L = Br⁻, I⁻; X = I⁻, BF₄⁻) where Nmedapsme binds as a tridentate and nmesme = N-methyl-S-methyldithiocarbazate. The related ternary nickel(II) complexes of formula, Ni(Nmedapsme)(nmetsc)Br₂ has also been prepared and characterized. X-ray crystal structures of [Ni(Nmedapsme)(nmesme)I]I·H₂O and [Ni(Nmedapsme)(nmesme)Br]BF₄·H₂O revealed that, in these complexes, the Nmedapsme ligand acts as a tridentate NNN donor while the distal S-donors are not coordinated. The bidentate (NS) ligand, nmesme coordinates to the nickel(II) ion via the amino nitrogen and the thione sulfur atoms, the sixth coordination site is occupied by an anion. In both complexes, the nickel(II) ion adopts a distorted octahedral configuration. The complex [Cu(nmesme)₂(ONO₂)]NO₃ was obtained from an unsuccessful attempt to complex copper(II) with Nmedapsme. Hydrolysis of the parent Schiff base Nmedapsme occurred during complexation. An X-ray crystallographic structure analysis shows that the complex, [Cu(nmesme)₂(ONO₂)]NO₃ has an approximately square-pyramidal geometry with the two nmesme ligands coordinated to the copper(II) ion as NS bidentate chelating agents via the amino nitrogen and thione sulfur atoms and the fifth coordination position of copper(II) is occupied by a monodentate nitrate ligand.     

Ternary complexes in solution. Comparison of the coordination tendency of some polybasic oxygen acids toward the binary complexes of Cu(II) andAMP,ADP orATP

Summary Potentiometric equilibrium measurements have been made at 25±0.1°C (=0.1 mol dm^–3 KNO₃) for the interaction of adenosine-5-mono-, -di- and -triphosphate (AMP,ADP andATP) and Cu(II) with biologically important secondary ligand acids (malic, maleic, succinic, tartaric, citric and oxalic acids) in a 1:1:1 ratio and the formation of various 1:1:1 mixed ligand complex species inferred from the potentiometricpH titration curves. Initial estimates of the formation constants of the resulting species and the acid dissociation constants ofAMP,ADP,ATP, and secondary ligand acid, have been refined with the SUPERQUAD computer program. In some systems logK values are positive, i.e. the ternary complexes are found to be more stable than the corresponding binary complexes. In some Cu(II) ternary systems the interligand interactions between the coordinate ligands, possibly H bond formation, have been found to be most effective in deciding the stability of the ternary complexes formed in solution. Stabilities of mixed ligand complexes increase in the orderAMP <ADP <ATP. With respect to the secondary ligands, the formation constants of the mixed ligand complexes decrease in the order succinic > maleic > tartaric > malic > citric > oxalic acid.

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Ternäre Komplexe in Lösung. Vergleich der Koordinationstendenz einiger polybasischer Sauerstoffsäuren gegenüber binären Komplexen von Cu(II) mitAMP,ADP oderATP

Zusammenfassung Es wurden potentiometrische Gleichgewichtsmessungen bei 25±0.1°C bei =0.1 mol dm^–1 KNO₃ durchgeführt, um die Wechselwirkung von Adenosin-5-mono-, -di- und triphosphat mit Cu(II) und biologisch relevanten Sekundärliganden wie Äpfel-, Malein-, Bernstein-, Wein-, Zitronen- und Oxalsäure im Verhältnis 1:1:1 festzustellen. Aus den potentiometrischenpH-Titrationskurven ergaben sich verschiedene 1:1:1 gemischte Ligandenkomplexe. Anfänglich abgeschätzte Komplexbildungskonstanten der Komplexe und Säuredissoziationskonstanten vonAMP,ADP undATP und den Sauerstoffsäuren wurden mittels des Computerprogramms SUPERQUAD verfeinert. In einigen Systemen ist logK positiv, demzufolge sind die ternären Komplexe stabiler als die korrespondierenden binären. In einigen ternären Cu(II)-Komplexen bestehen zwischen den Liganden Wechselwirkungen, vermutlich auf der Basis von stabilitätsfördernden Wasserstoffbrückenbindungen. Die Stabilitäten der gemischten Komplexe steigen in der ReihenfolgeAMP <ADP <ATP. Bezüglich der Sekundärliganden ergibt sich für die Bildungskonstanten der ternären Komplexe die Reihung Bersteinsäure > Maleinsäure > Weinsäure > Äpfelsäure > Zitronensäure > Oxalsaure.

     

Synthesis of Some Octahedral Nickel(II) Complexes of One Isomer of Isomeric Me8[14]anes: X-ray Structure of Diisothiocyanato(3,10-C-meso-3,5,7,7,10,12,14,14-octamethyl-1,4,8,11-tetraazacyclotetradecane, LC)nickel(II), [NiLC(NCS)2]

One isomer, L_C of the isomeric Me₈[14]anes, L_A, L_B and L_C; on reaction with Ni(NCS)₂ produces a six coordinate octahedral diisothiocyanato complex, [NiL_C(NCS)₂]. This complex undergoes axial substitution reactions with the small ligands to yield corresponding monosubstituted derivatives having general formula [NiL_C(NCS)X] whereas X = Cl, Br, I, NO₂ or NO₃. The complexes have been characterized on the basis of analytical, spectroscopic, magnetic and conductance data. The structure of [NiL_C(NCS)₂] (triclinic, space group P?1, α = 8.0421(17) Å, β = 8.9085(18) Å, χ = 9.687(2) Å, α = 67.561(3) Å, β = 82,896(4) Å, ζ = 598.7(2) Å³, Z = 2, Dc = 1.352 mg/m³, μ(Mo Kα) = 1.003 mm^?1) was confirmed by X-ray crystallography.     

Synthesis and structural studies of mixed-ligand complexes

Seven mixed-ligand complexes of cobalt(II), nickel(II) and copper(II) containing benzoylacetone andL-proline (HL¹), 2-pyrrolidone-5-carboxylic acid (HL²) orL-thioproline (HL³) were prepared and characterized by means of elemental analysis, IR, electronic spectra, magnetic moment measurements and molar conductance. Both HL¹ and HL² coordinate with these metal ions in a neutral zwitterionic form (-NH₂-CH-COO^–), whereas HL³ coordinates as a monobasic chelating agent (O/N). The continuous thermochromism of the nickel(II) complex of HL¹ (2) was attributed to a geometry change; it was investigated by DTA, TG, electronic spectra and X-ray powder diffraction techniques.     

Synthesis,structural characterization and solvent effect of copper(II) complexes with a variational multidentate Salen-type ligand with bisoxime groups

Four new solvent-induced Cu(II) complexes with the chemical formulae [{Cu(HL)(CH₃OH)}₂Cu] · CH₃OH (1), [{(Cu(HL))₂(CH₃CH₂OH)₂}Cu] (2), [{CuL(H₂O)}₂Cu₂] · 2CH₃CH₂CH₂OH (3) and [{(Cu(HL))₂(CH₃CH₂CH₂CH₂OH)₂}Cu] (4), where H₄L = 6,6′-dihydroxy-2,2′-[ethylenediyldioxybis(nitrilomethylidyne)]diphenol, have been synthesized and characterized by elemental analyses, ¹H NMR, FT-IR, UV–Vis spectra, TG-DTA, molar conductances and X-ray crystallography. Complexes 1, 2 and 4 have an elongated square-pyramidal geometry with an unusually long bond from the penta-coordinated Cu(II) centres to the oxygen atoms of the apically coordinated solvent (methanol, ethanol or n-butanol) molecules for the terminal Cu(II) ions, and a square planar geometry distorted tetrahedrally for the central Cu(II) ion. In complex 3, the terminal Cu(II) ions have trigonal bipyramidal coordination geometries constituted by equatorial O₂N donor sites, with one oxygen atom from one of the coordinated water molecules and one nitrogen atom from a completely deprotonated L⁴⁻ ligand unit in the axial positions, and the central Cu(II) ions are in slightly tetrahedrally distorted square planar geometries constituted by four phenoxo oxygen donors from two completely deprotonated L⁴⁻ ligand units, and these form a tetrametal Cu–O–Cu–O–Cu–O–Cu–O eight-membered ring. These four complexes exhibit strong hydrogen bonding interactions in the solid state. Moreover, co-crystallizing n-propanol molecules link two other adjacent complex molecules into a self-assembled infinite 2D supramolecular structure via the intermolecular hydrogen bonds in complex 3.     

The synthesis and characterization of three new vic -dioximes and their nickel(II), copper(II) and cobalt(II) complexes

Three new vic-dioximes, [L¹H₂], N-(4-ethylphenyl)amino-1-acetyl-1-cyclohexenylglyoxime, [L²H₂], N-(4-butylphenyl)amino-1-acetyl-1-cyclohexenylglyoxime, and [L³H₂], N-(4-methoxyphenyl)amino-1-acetyl-1-cyclohexenylglyoxime were synthesized from 1-acetyl-1-cyclohexeneglyoxime and the corresponding substituted aromatic amines. Metal complexes of these ligands were also synthesized with Ni(II), Cu(II), and Co(II) salts. These new compounds (ligands and complexes) were characterized with FT–IR, magnetic susceptibility measurement, molar conductivity measurements, mass spectrometry measurements, thermal methods (e.g. thermal gravimetric analysis), ¹H NMR (Nuclear Magnetic Resonance) and ¹³C NMR spectral data and elemental analyses.     

Synthesis and characterization of potassium 1,3-bis(N-methylpiperazino)propan-2-O-xanthate and the complexes of Co(II), Ni(II) and Cu(I) ions

Potassium 1,3-bis(N-methyl piperazino)propan-2-O-xanthate (LK), and its complexes with Co(II), Ni(II) and Cu(I) ions have been prepared and characterized as [CoL₂(H₂O)₂], [NiL₂(H₂O)₂]·2H₂O and CuL·2H₂O by FT-IR, ¹H and ¹³C?NMR spectroscopies, elemental analyses, magnetic susceptibility and TGA techniques.     

Synthesis,spectroscopy and thermal analysis of copper(II) hydrazone complexes

The chelating behavior of some hydrazones towards Cu(II) has been investigated. The isolated complexes were characterized by elemental analysis, magnetic moment, spectra (electronic, IR and ms) and thermal measurements. The IR spectra showed that the ligands are deprotonated in the complexes as bidentate, tridentate and binegative tridentate. Protonation constants of the ligands and the stability constants of their Cu(II) complexes were calculated. Square-planar, square-pyramidal, tetrahedral and/or distorted octahedral structures are proposed. The TGA data help to confirm the chemical formula of the complexes and indicated the steps of their thermal degradations.     

Synthesis,characterization, molecular modeling,and thermal analyses of bioactive Co(II) and Cu(II) complexes with diacetylmonoxime and different amines

Condensation of diacetylmonoxime with 2-amino-5-mercapto-1,3,4-thiadiazole, 2-amino-1,3,4-thiadiazole or 3-amino-5-methylisoxazole in the presence of Co(II) and Cu(II) salts with different anions produced nine complexes. The synthesized complexes have been characterized by elemental analyses, molar conductivities, thermal analyses, magnetic moments, IR, electron spin resonance, and UV-Vis spectral studies. The spectral data show that sulfur, oxygen, and nitrogen participate in chelation with the metal ions. The complexes are tetrahedral, octahedral, or square planar based on the amine used and the nature of anion. Molar conductance measurements of the complexes in DMF indicate non-electrolytes. CS Chem 3-D Ultra Molecular Modeling and Analysis Program has been used for optimization of the molecular structures of some complexes. In vitro cytotoxicities of the complexes were tested against different carcinoma cell lines. Antimicrobial activities of the complexes were screened against Gram-positive (Staphylococcus aureus), Gram negative bacteria (Escherichia coli), and fungal species (Aspergillus flavus, Candida albicans, and Microsporum canis).     

A thermal study of Cu(II) compounds formed with piperazine derivatives

The thermal behaviour of some Cu(II) compounds formed with 1,4-disubstituted piperazine derivatives has been studied. The investigations were performed on a MOM 1500 derivatograph. The endothermic effects observed at 170–180°C are associated with the processes of dehydration and dehalogenation of the compounds, with general formula LH₂·CuCl₄·H₂O, whereL is the piperazine derivative. The residue at 600°C remains relatively constant.     

Synthesis,structure and properties of some copper(II) complexes containing an ONO donor Schiff base and substituted imidazole ligands

Five new mixed ligand coper(II) complexes, viz. [Cu(SAA)(H₂O)] (1), [Cu(SAA)(MeImH)] (2), [Cu(SAA)(EtImH)] (3), [Cu(SAA)(BenzImH)] (4) and [Cu(SAA)(MebenzImH)] (5), where SAA = salicylideneanthranilic acid, MeImH = 2-methylimidazole, EtImH = 2-ethylimidazole, BenzImH = benzimidazole, MebenzImH = 2-methylbenzimidazole, have been synthesized and characterized by means of elemental analysis, FAB mass spectrometry, magnetic susceptibility, X-band EPR, electronic spectroscopy, IR and cyclic voltammetry. The frozen solution EPR spectra of the complexes have shown axial features. Single crystal X-ray analysis of 2 and 3 has revealed the presence of a distorted square planar geometry (N₂O₂) in the complexes. The superoxide dismutase (SOD) activity of the present complexes has also been measured and discussed.     

Synthesis and X-ray crystallographic studies of Ni (II) and Cu (II) complexes of [5-(4-pyridyl)-1,3,4] oxadiazole-2-thione/thiol formed by transformation of N-(pyridine-4-carbonyl)-hydrazine carbodithioate in the presence of ethylenediamine

The reaction of [M(H₂L)₂] [M = Ni(II) Cu(II)] (K⁺H₂L⁻ = N-(pyridine-4-carbonyl)-hydrazine carbodithioate) with excess of ethylenediamine (en) gave mixed ligand complexes [Ni(en)₂(4-pytone)₂] (4-pytone = 5-(4-pyridyl)-1,3,4-oxadiazole-2-thione), and [Cu(en)₂](4-pytol)₂·H₂O (4-pytol = 5-(4-pyridyl)-1,3,4-oxadiazole-2-thiol). The metal complexes have been characterized with the aid of elemental analyses, IR, magnetic susceptibility and single crystal X-ray studies. Complexes (1) and (2) crystallize in monoclinic system, space group P_{1 21}/n₁ and C₂/c, respectively. The ligand after cyclization is present in the deprotonated thiol form in the Cu(II) complex where it is ionically bonded through sulfur. In the Ni(II) complex (1) bonding of the ligand take place through oxadiazole nitrogen and the ligand exists as the thione form.     

Thermal stability of some azo-derivatives and their complexes

this paper deals with the first investigation concerning the thermal stability of two 1-(2-benzothiazolyl)-3-methyl-4-azo-pyrazil-5-one derivatives and their Cu(II) coordination compounds of type ((C₄H₉)₄N)₂[Cu(L)₂]. The thermal decomposition steps were established. This revised version was published online in July 2006 with corrections to the Cover Date.     

Mononitrosated and phenylamido substituted chelate linkage isomers of quadridentate Schiff base copper(II) complexes

The nitrosation of monophenylamido substituted quadridentate Schiff base complexes of copper(II) are observed to adopt N-bonded isonitroso coordination whereas the phenylisocyanation of the corresponding mononitrosated quadridentate complexes are found to prefer O-bonded isonitroso coordination.