Preparation, structures and properties of dinuclear and trinuclear copper(II) complexes bridged by one oximato and one hydroxo ligands

The dinuclear and trinuclear copper(II) complexes [Cu₂(L)(OH)(ClO₄)(phen)(H₂O)]ClO₄ · [Cu₂(L)(OH)(ClO₄)₂(phen)(CH₃OH)] (1) and [Cu₃(L)₂(OH)₂(H₂O)₂](NO₃)₂ (2) (HL=2-[2-(α-pyridyl)ethyl]imino-3-butanone oxime and phen=1,10-phenanthroline) were prepared and their crystal structures have been determined by X-ray crystallography. Complex 1 is composed of [Cu₂(L)(OH)(ClO₄)(phen)(H₂O)]ClO₄ (1a) and [Cu₂(L)(OH)(ClO₄)₂(phen)(CH₃OH)] (1b). In 1a and 1b, one oximato of L and one hydroxo group bridge two copper(II) ions. The linear trinuclear cation [Cu₃(L)₂(OH)₂(H₂O)₂]²⁺ in 2 is centrosymmetric, and one oximato and one hydroxo group bridge the central and terminal copper(II) ions. The strong antiferromagnetic interactions within the dinuclear and trinuclear complexes 1 and 2 have been observed (2J=∼−900 cm⁻¹ for 1 and 2, respectively, H=−2JS₁·S₂).     

Superoxide dismutase–mimicking activities of dinuclear Cu(II) complexes with ligands containing a tetrathioether-tetraamino moiety

The superoxide scavenging activities of copper(II) complexes with the ligands, 6,6′-methylene-bis(5′-amino-3′,4′-benzo-2′-thiapentyl)-1,11-diamino-2,3:9,10-dibenzo-4,8-dithiaundecane (H₄L), and 6,6′-bis(5′-amino-3′,4′-benzo-2′-thiapentyl)-1,11-diamino-2,3:9,10-dibenzo-4,8-dithiaundecane (H₄L′), were investigated by xanthine–xanthine oxidase (X/XO) assays using nitroblue tetrazolium (NBT) as indicator molecule, and the results were compared with respect to the particular type of anion (ClO·4, Cl^·, NO·3) on the apical site of the copper(II) complexes. All of the complexes inhibited the reduction of NBT by superoxide radicals, with the [Cu₂(L′)](ClO₄)₂ complex exhibiting the highest scavenging activity against superoxide radicals among the complexes examined. The catalytic efficiency of the complexes for dismutation of superoxide radicals depends on the particular anion liganded to Cu(II) ion in the complexes, and the order of potency was observed to be ClO₄ > Cl > NO·3 in phosphate buffer at pH 7.40. The Cu(II)-H₄L′ complexes had the lowest IC₅₀ and catalytic rate constant values indicating that the distorted geometry of the Cu(II)-H₄L′ complexes influence their catalytic activities for dismutation of superoxide radicals more efficiently. The difference in the activities of the complexes toward superoxide radicals can also be attributed to the nature of the anions on the apical site of the copper(II) complexes and the superoxide dismutase-like activity. © 1997 John Wiley & Sons, Inc. J Biochem Toxicol 12: 53–59, 1998     

Diphosphines as bridging ligands in polymeric and dimeric thione-S-ligated Ag(I) nitrate complexes

Reactions of silver(I) nitrate with equimolar amounts of the diphos ligands 1,4-bis(diphenylphosphino)butane (dppb) or 1,2-bis(diphenylphosphino)ethane (dppe) and some heterocyclic thiones (L) in acetonitrile/methanol solvent afforded mixed-ligand complexes, the nature of which was found to be strongly influenced by the backbone length of the diphosphine ligand. The longer chained diphos ligand formed a series of dinuclear complexes of the type [Ag(dppb)(L)]₂(NO₃)₂ with both the diphosphine and thione ligands acting as bridging ligands between the two four-coordinate pseudo-tetrahedrally coordinated metal centers. In the unique case of L=4-methyl-5-trifluoromethyl-4H-1,2,4-triazoline-3(2H)-thione (mftztH), the reaction proceeded under exclusion of the thione ligand from the coordination sphere and coordination of the nitrate anions instead, leading to the diphosphine-doubly bridged dimeric compound [Ag(dppb)(NO₃)]₂. On the other hand, the complexes produced when using the short bite 1,2-bis(diphenylphosphino)ethane (dppe) turned out to be diphosphine-bridged cationic polymers of the type [Ag(dppe)(L)₂]_n(NO₃)_n. The structures of one representative for each of the two aforementioned series of complex compounds, namely [Ag(dppb)(py2SH)]₂(NO₃)₂ · 2H₂O and [Ag(dppe)(pymtH)₂]_n(NO₃)_n, have been established by single-crystal X-ray diffraction.     

Binuclear copper(II) complexes of tetradentate (Ne) diazine ligands. Crystal structures of [μ-1,4-Bis(4,6-dimethyl-2-pyridylamino)phthalazine-N,μ-N3,μN3,N]-(μ-Dichloro)dichlorodicopper(II), [μ-3,6-Bis(2-pyridylthio)pyridazine-N,μ-N1,μ-N2,N] (μ-dichloro)dichlorodicopper(II) ethanol,and 3,6-Bis(2-pyridylthio)-pyridazine

The X-ray structures of two binuclear copper(II) chloride complexes of the tetradentate ligands 1,4- bis(4,6-dimethyl-2-pyridylamino)phthalazine (PAP46Me) and 3,6-bis(2-pyridylthio)pyridazine are reported. [Cu₂(PAP46Me)Cl₄] (1) and [Cu₂(PTP)Cl₄]· CH₃CH₂OH (2) contain triply bridged binuclear centres involving a diazine (NN) and two chlorobridges with copper-copper separations in the fange 3.19–3.25 Å and distorted square pyramidal copper stereochemistry. The reduced room temperature magnetic moments indicate antiferromagnetically coupled binuclear copper(II) centres.Complex 1 forms green crystals with a= 15.795(3), b=10.661(3), c=16.155(4) Å, β= 113.82(3)°, C2/c, Z = 4, R_f=0.031. Complex (2) forms green crystals with a=33.9022(8), b= 9.1626(5), c= 15.7885(5) Å,β= 114.853(2)°, C2/c, Z=8, R_f=0.047. The structure of the ligand PTP is also reported and compared with that of 2.     

Synthesis, characterization, and DNA binding and cleavage properties of copper(II)-tryptophanphenyl-alanine-1,10-phenanthroline/2,2'-bipyridine complexes

The mononuclear dipeptide‐based Cu^II complexes [Cu^II(trp‐phe)(phen)(H₂O)] ⋅ ClO₄ ( 1 ) and [Cu^II(trp‐phe)(bpy)(H₂O)] ⋅ ClO₄ ( 2 ) (trp‐phe=tryptophanphenylalanine, phen=1,10‐phenanthroline, bpy=2,2′‐bipyridine) were isolated, and their interaction with DNA was studied. They exhibit intercalative mode of interaction with DNA. The intercalative interaction was quantified by Stern Volmer quenching constant (K_sq=0.14 for 1 and 0.08 for 2 ). The Cu^II complexes convert supercoiled plasmid DNA into its nicked circular form hydrolytically at physiological conditions at a concentration as low as 5 μM (for 1 ) and 10 μM (for 2 ). The DNA hydrolysis rates at a complex concentration of 50 μM were determined as 1.74 h⁻¹ (R=0.985) for 1 and 0.65 h⁻¹ (R=0.965) for 2 . The rate enhancement in the range of 2.40–4.10×10⁷‐fold compared to non‐catalyzed double‐stranded DNA is significant. This was attributed to the presence of a H₂O molecule in the axial position of the Cu complexes.     

Mononuclear rhodium(I) complexes of 4-Amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole. Crystal structure of [Rh(CO)2(NH2bpt)]ClO4

Reaction of 4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole (NH₂bpt) or its potassium salt (KNHbpt) with several rhodium(I) compounds, produces new neutral and cationic complexes of Rh(I). One of the complexes [Rh(CO)₂(NH₂bpt)]ClO₄ has been characterized by single-crystal X-ray diffraction. The crystals are monoclinic, space group P2₁/n, with a = 17.6130(6), b = 11.3072(2), c = 9.0013(2) Å, β = 101.536(2)° and Z = 4. The structure has been refined to R = 0.049.     

Synthesis and crystal structures of di- and tetra-nuclear dicarboxylate-bridged copper(II) complexes

Three new Cu(II) complexes, [Cu₂(C₃H₂O₄)(phen)₂(H₂O)₃](NO₃)₂(H₂O)₂ (1) (C₃H₂O₄ = malonate, phen = 1,10-phenanthroline), [Cu₂(C₄H₄O₄)(phen)₂(H₂O)₂](NO₃)₂ (2) (C₄H₄O₄ = succinate), and {[Cu₂(phen)₂(H₂O)(NO₃)]₂(C₅H₆O₄)₂}(NO₃)₂ (3) (C₅H₆O₄ = glutarate) have been synthesized and characterized by elemental analysis, infrared spectroscopy, thermogravimetric analysis, and single crystal X-ray diffraction. The X-ray analysis reveals that the structures of 1 and 2 are of dinuclear copper(II) complexes bridged by malonate and succinate dianions, respectively, and 3 is a tetranuclear species formed by two {[Cu₂(phen)₂(H₂O)(NO₃)](C₅H₆O₄)} fragments. The copper ions in 1 and 3 show square-pyramidal coordination geometry, while the copper ions in 2 exhibit a square planar geometry. In each complex, the dicarboxylate ligand is coordinated to copper ions as a chelate and monodentate (1), bis-monodentate (2), and bis-bridging ligand toward the copper ions with syn-syn coordination mode (3).     

Synthesis and characterization of new oligomeric and polymeric complexes based on the [Cu(bpca)] unit [Hbpca = bis(2-pyridylcarbonyl)amine]

Five novel bpca-based Cu(II) polynuclear coordination compounds [Hbpca = bis(2-pyridylcarbonyl)amine] were prepared using the [Cu(bpca)(H₂O)₂](NO₃)·2H₂O (1) building block and characterized by single crystal X-ray diffraction. We have also isolated and characterized two new crystal forms of the starting species, with lower water contents. Three of the new products are dinuclear complexes obtained by reacting 1 with different rigid or flexible spacer ligands: [Cu₂(bpca)₂(H₂O)₂(bipy)](NO₃)₂·6H₂O (2) (bipy = 4,4′-bipyridine) and [Cu₂(bpca)₂(H₂O)₂(bpete)](NO₃)₂·xH₂O (3) [bpete = (E)-1,2-di(pyridin-4-yl)ethane] are linear dumbbell-like species with Cu?Cu separations of 11.075 and 13.275 Å, respectively. The third dinuclear compound, [Cu₂(bpca)₂(H₂O)₂(bpx)](NO₃)₂·8H₂O (4) [bpx = 1,4-bis((1H-pyrazol-1-yl)methyl)benzene], with the flexible bpx ligand, assumes an unusual S-shaped conformation and shows a quite shorter Cu?Cu contact of 6.869 Å only. We have also obtained a chiral 1D neutral polymeric complex, [Cu₃(bpca)₂(bipy)₃(NO₃)₄]·6H₂O (5), that shows a central linear -Cu-bipy-Cu- chain, with all these Cu atoms connected to two lateral [Cu(bpca)(NO₃)₂]⁻ groups on two opposite sides by means of bipy spacers. An unprecedented type of Cu(II) neutral trinuclear complex, [Cu₃(bpca)₂(H₂O)₂(NO₃)₂] (6), was obtained which has a centrosymmetric structure with two external [Cu(bpca)(NO₃)₂]⁻ units chelating on a central copper atom via the two pairs of carbonyl groups of the bpca ligands. The central metal is octahedral with two axial water molecules, while the two lateral Cu atoms are in square pyramidal geometry; the Cu?Cu separation is 5.205 Å. The magnetic properties of 6 have been rationalized through a ferromagnetic coupling between the central metal ion and the peripheral ones which are coupled by a smaller antiferromagnetic interaction. DFT calculations have been also performed in order to give a better insight into magnetic interactions.     

Three coordination modes of the pentadentate ligand 2,6-diacetylpyridinedisemicarbazone

The pentadentate ligand 2,6-diacetylpyridinedisemicarbazone, DAPSC, reacts with Cr(NO₃)₃·9H₂O and forms two kinds of complexes. At pH=3, the ligand is singly-deprotonated and crystals of [Cr- (DAPSCH)(H₂O)₂](NO₃)₂·H₂O (Ia) are obtained. Evaporation of a solution at pH=0, yields crystals of [Cr(DAPSC)(H₂O)₂](NO₃)₃·2H₂O (II) in which the ligand is fully protonated. The reaction of DAPSC with UO₂(O₂CCH₃)₂ in methanol, followed by crystallization of the product from DMSO yields crystals of [UO₂(DAPSC2H)(H₂O)]·2DMSO (III) in which the ligand is fully deprotonated. Compound Ia is monoclinic, space group P2₁/n with a=11.746(1), b=14.752(2), c=11.866(1) Å,β=105.53(2)°, V= 1981(1) ų and Z=4. Compound II is monoclinic, space group, P2₁/n with a=38.000(3), b= 14.939(2), c=8.233(1) Å, β=96.12(2)°, V= 4647(1) Å and Z=8. Compound III is monoclinic, space group P2₁/n with a=18.048(2), b=15.207(2), c=8.842(1) Å,β=97.72(2)°, V=2405(1) ų and Z=4. The structures were refined using 2084, 4169 and 2516 reflections to R values of 4.4%, 7.8% and 4.8% respectively.     

Copper(II) complexes of 3-amino-1,2,4-triazine and 2-aminopyrazine: Strategies for designing crystalline materials using coordination polymers

Reaction of 3-amino-1,2,4-triazine (3-atz) or 2-aminopyrazine (2-apz) with Cu(hfac)₂·xH₂O led to the formation of the monometallic and trimetallic complexes Cu(hfac)₂(3-atz)₂ (1), Cu₃(hfac)₆(3-atz)₂ (2), Cu(hfac)₂(2-apz)₂ (3) and Cu₃(hfac)₆(2-apz)₂ (4). The azine molecules behave as both monodentate and bridging bidentate ligands. The Cu(II) ions exhibit a range of coordination geometries. In 1 and 3, the complex is distorted octahedral with the Jahn-Teller axis lying along one of the O-Cu-O axes. In 2 and 4, the central Cu(II) ion is also distorted octahedral with the Jahn-Teller axis lying along the N-Cu-N axis, while the terminal Cu(II) ions are five-coordinate. Structure analysis reveals that addition of the amino-substituent makes the ligands more coordinating, leading to shorter CuN bonds. In the case of 4, this results in a stronger magnetic superexchange pathway and the complex exhibits antiferromagnetic behavior at low temperatures.     

Effect of copper-substitution on the structure and nuclearity of Cu(II)-pyrazolates: from trinuclear to tetra-, hexa- and polynuclear complexes

The influence of terminal ligands on the structure and nuclearity of copper(II)-pyrazolates has been investigated. Exchange of the chloride ligands of [Cu₃(μ₃-X)(μ-pz)₃Cl₃]ⁿ⁻ (X=O, OH; n=2, 1) or [Cu₃(μ₃-Cl)₂(μ-pz)₃Cl₃]²⁻ complexes for cyanate, acetate or bromide ligands maintains the integrity of the triangular species: PPN[Cu₃(μ₃-OH)(μ-pz)₃(NCO)₃], PPN[Cu₃(μ₃-OH)(μ-pz)₃(O₂CCH₃)₃(H₂O)] · H₂O, Bu₄N[Cu₃(μ₃-OH)(μ-pz)₃(O₂CCH₃)₃] · 3H₂O and (Bu₄N)₂[Cu₃(μ₃-Br)₂(μ-pz)₃Br₃] have been prepared and characterized by spectroscopic and X-ray diffraction techniques, respectively. In contrast, tetranuclear complexes (Bu₄N)₂[Cu₄(μ₃-OH)₂(μ-4-X-pz)₂(μ-O₂CPh)₂(O₂CPh)₄] (X=H, Cl, Br, NO₂) and the hexanuclear complex (Bu₄N)₂[Cu₆(μ₃-O)(μ₃-OH)(μ-4-NO₂-pz)₆(μ-O₂CPh)₃(O₂CPh)₂(H₂O)] · (CH₂Cl₂)_0.5 have been obtained on substitution for benzoate ligands. An attempt to partially substitute the chlorides for tert-butoxide ligands, also provided a tetranuclear complex, (Bu₄N)₂[Cu₄(μ-OH)₂(μ-pz)₄Cl₄], without incorporation of the incoming ligand. Similarly, removal of all chloride ions in the absence of an appropriate substituting ligand leads to higher nuclearity metallacycles [Cu(μ-OH)(μ-pz)]_n (n=6, 8, 9, 12, 14).     

Synthesis, characterization, and magnetic properties of new homotrinuclear bis(oxamato) copper(II) complexes with an asymmetric central N,N′-bridge

The new mononuclear bis(oxamato) complex [n-Bu₄N]₂[Cu(obbo)] (1) (obbo=o-benzyl-bis(oxamato)) has been synthesized as a precursor for trinuclear oxamato-bridged transition metal complexes. Starting from 1 the homotrinuclear complexes [Cu₃(obbo)(pmdta)₂(NO₃)](NO₃)·CH₂Cl₂·H₂O (2) and [Cu₃(obbo)(tmeda)₂(NO₃)₂(dmf)] (3) have been prepared, where pmdta = N,N,N′,N″,N″-pentamethyldiethylenetriamine, tmeda = N,N,N′,N′-tetramethylethylenediamine and dmf = dimethylformamide. The crystal structures of 1-3 were solved. The magnetic properties of 2 and 3 were studied by susceptibility measurements versus temperature. For the intramolecular J parameter values of −111 cm⁻¹ (2) and −363 cm⁻¹ (3) were obtained.     

Synthesis, structures, and magnetic properties of dicopper(II) and dinickel(II) complexes with a new bis(macrocycle), 7,7-(2-hydoxypropane-1,3-diyl)bis{3,7,11,17-tetraazabicyclo[11.3.1]- heptadeca-1(17),13,15-triene}

A new bis(macrocycle) ligand, 7,7^′-(2-hydoxypropane-1,3-diyl)-bis{3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17),13,15-triene} (HL), and its dicopper(II) ([Cu₂(HL)Cl₂](NO₃)₂ · 4H₂O (4a), [Cu₂(HL)I₂]I₂ · H₂O (4b)) and dinickel(II) ([Ni₂(L)(OH₂)](ClO₄)₃ (5a), [Ni₂(L)(OH₂)]I₃ · 2H₂O (5b), [Ni₂(L)N₃](N₃)₂ · 7H₂O (5c)) complexes have been synthesized. The alkoxide bridged face-to-face structure of the dinickel(II) complex 5c has been revealed by X-ray crystallography, as well as the “half-opened clamshell” form of the bis(macrocyclic) dicopper(II) complex 4b. Variable temperature magnetic susceptibility studies have indicated that there exists intramolecular antiferromagnetic coupling (J=−33.8 cm⁻¹ (5a), −32.5 cm⁻¹ (5b), and −29.7 cm⁻¹ (5c)) between the two nickel(II) ions in the nickel(II) complexes.     

Mono- and dinuclear (o-thioetherphenolato)-copper(II) complexes. Structural models for galactose oxidase

Three new o-thioetherphenol ligands have been synthesized: 1,2-bis(3,5-di-tert-butyl-2-hydroxyphenylsulfanyl)ethane (H₂bse), 1,2-bis(3,5-di-tert-butyl-2-hydroxyphenylsulfanyl)benzene (H₂bsb), and 4,6-di-tert-butyl-2-phenylsulfanylphenol (Hpsp). Their complexes with copper(II) were prepared and investigated by UV-Vis-, EPR-spectroscopy; their electro- and magnetochemistry have also been studied: [Cu^II(psp)₂] (1), [Cu^II₂(bse)₂] (2), [Cu^II₂(bsb)₂] (3), [Cu^II(bsb)(py)₂] (4). The crystal structures of the ligands H₂bse, H₂bsb, Hpsp and of the complexes 1, 2, 3, 4 have been determined by X-ray crystallography.     

Rhodium(III) cis-dihydrido complexes with 3,6-bis(2′-pyridyl)pyridazine (dppn) and bidiazines. Crystal and molecular structure of [Rh(H)2(dppn)(PPh3)2]PF6· CH2Cl2

The acetone complex [Rh(H)₂(acetone)₂(PPh₃)₂]- PF₆ reacts with bidiazines and 3,6-bis(2′-pyridyl)- pyridazine (dppn) giving the air stable cis-dihydrido rhodium(III) [Rh(H)₂(L)(PPh₃)₂]PF₆ complexes. The structure of the dichloromethane solvate of [Rh(H)₂(dppn)(PPh₃)₂]PF₆ has been determined by X-ray crystal structure analysis. Crystals are monoclinic, space group P2₁/a, with a = 18.629(6), b = 15.339(5), c = 17.146(5) Å, β = 101.02(3)° and Z = 4. The structure has been solved from diffractometer data by Patterson and Fourier methods and refined by block-matrix least-squares to R = 0.076 for 6225 observed reflections. In the structure discrete [Rh(H)₂(dppn)(PPh₃)₂]⁺ cationic complexes, PF₆⁻ anions and dichloromethane solvent molecules are present. The Rh atom is octahedrally surrounded by two cis hydride ligands and by two cis nitrogen atoms from a dppn molecule acting as a bidentate chelating ligand through two neighbouring pyridyl and pyridazinyl nitrogen atoms. Two P atoms from PPh₃, ligands in trans apical positions complete to octahedral the coordination of Rh.     

CoX2(NO)(PMe3)2 Complexes: an example of the influence of X (X = CI,Br, I,NO2) on the stereochemistry and electronic structure of the five-coordinate {CoNO}8 complexes

CoX₂(NO)(PMe₃)₂ complexes (X = Cl, Br, I, NO₂) exhibit markedly different ν(NO) stretching frequencies and different geometries. The structure of CoI₂(NO)(PMe₃)₂ (1) and CoCl₂(NO)(PMe₃)₂ (2) have been determined by X-ray diffraction. Both crystallize in the orthorhombic system, Pnma space group with four molecules in a cell of the following dimensions: for 1, a = 10.497(2), b = 10.694(2), c = 13.975(2) Å, ν= 1568.8, ų; for 2, a = 9.607(2), b = 10.689(2), c = 13.512(3) Å, ν= 1387.5 ų. The structures were refined to conventional R values of R = 0.040 from 1630 reflections for 1 and R = 0.033 from 976 reflections for 2. In both cases, the coordination geometry about the five-coordinate cobalt atom is approximately trigonal bipyramidal, with the NO group sharing the equatorial positions with the halide ligands. Structure 2 is disordered, which prevents any precise structural characterization. In (1), the CoNO angle is 179.2(19)° and the Co NO distance is 1.728(23) Å; v(NO) is 1753 cm⁻¹. CoCl₂(NO)(PMe₃)₃ shows a v(NO) vibration at 1637 cm⁻¹. Co(NO₂)₂(NO)(PMe₃)₂ with v(NO) = 1658 cm⁻¹ has been proposed as a square pyramidal structure with a bent apical CoNO. These differences in NO stretching frequencies and geometries are discussed.     

Synthesis, crystal structure, antibacterial assay and DNA binding activity of new binuclear Cu(II) complexes with bridging oxamidate

Two new binuclear copper complexes, [Cu₂(oxpn)(bpy)(pic)(H₂O)](pic) (1) and [Cu₂(oxpn)(Me₂bpy)(pic)](pic) (2) [H₂oxpn = N,N′-bis(3-aminopropyl)oxamide; Hpic = 2,4,6-trinitrophenol; bpy = 2,2′-bipyridine; Me₂bpy = 4,4′-dimethyl-2,2′-bipyridine], have been synthesized and characterized by elemental analyses, conductivity measurements, IR, UV-visible spectroscopy and single crystal X-ray analyses. Both complexes have similar molecular structures. In complex 1, the central two Cu(II) atoms are bridged by cis-oxpn²⁻ with the Cu1-Cu2 separation of 5.221 Å and the polyhedron of each copper atom is a square-pyramid. Similarly, complex 2 is a cis-oxpn²⁻-bridged binuclear complex with the Cu1-Cu2 separation of 5.196 Å. Cu1(II) central atom situated in a tetrahedral geometry is four-coordinated and Cu(II) atom situated in a square-pyramidal geometry is five-coordinated. Hydrogen bonding interactions and π-π stacking interactions link the binuclear copper complex 1 or 2 into a 2D infinite network. The antibacterial assays indicate that the two complexes showed better activities than their ligands. The interactions of the two binuclear complexes with herring sperm DNA (HS-DNA) have been studied by UV absorption titration, fluorescence titration and viscosity measurements. The results suggest that the two binuclear complexes bind to HS-DNA via an intercalative mode.     

Effect of factor XIII levels and polymorphisms on the risk of myocardial infarction in young patients

The aim of this work was the synthesis, characterization, and cytotoxicity evaluation of three new Ru(II) complexes with a general formula [Ru(Spy)(bipy)(P-P)]PF₆ [Spy = pyridine-6-thiolate; bipy = 2,2′-bipyridine; P-P = 1,2-bis(diphenylphosphine)ethane (1); 1,3-bis(diphenylphosphine) propane (2); and 1,1′-bis(diphenylphosphino)ferrocene] (4). Complex (3) with the 1,4-bis(diphenylphosphine)butane ligand, already known from the literature, was also synthesized, to be better studied here. The cytotoxicities of the complexes toward two kinds of cancerous cells (K562 and S-180 cells) were evaluated and compared to normal cells (L-929 and PBMC) by MTT assay. The complex [Ru(Spy)(bipy)(dppb)]PF₆ (3) was selected to study both the cellular and molecular mechanisms underlying its promising anticancer action in S-180 cells. The results obtained from this study indicated that complex (3) induces cell cycle arrest in the G0/G1 phase in S-180 cells associated with a decrease in the number of cells in S phase. After 24 and 48 h of exposure to complex (3), the cell viability decreased when compared to the negative control. Complex (3) does not appear to be involved in the DNA damage, but induced changes in the mitochondrial membrane potential in S-180 cells. Furthermore, there was also an increase in the gene expression of Bax, Caspase 9, and Tp53. According to our results, complex (3) induces cell apoptosis through p53/Bax-dependent intrinsic pathway and suppresses the expression of active antiapoptotic Bcl-2 protein.     

Tetra-, penta- and hexacoordinate copper(II) complexes with N3 donor isoindoline-based ligands: Characterization and SOD-like activity

Reaction of 1,3-bis(2′-Ar-imino)isoindolines (HLⁿ, n = 1-7, Ar = benzimidazolyl, N-methylbenzimidazolyl, thiazolyl, pyridyl, 3-methylpyridyl, 4-methylpyridyl, and benzthiazolyl, respectively) with Cu(OCH₃)₂ yields mononuclear hexacoordinate complexes with Cu(Lⁿ)₂ composition. With cupric perchlorate square-pyramidal [Cu^II(HLⁿ)(NCCH₃)(OClO₃)]ClO₄ complexes (n = 1, 3, 4) were isolated as perchlorate salts, whereas with chloride Cu^II(HLⁿ)Cl₂ (n = 1, 4), or square-planar Cu^IICl₂(HLⁿ) (n = 2, 3, 7) complexes are formed. The X-ray crystal structures of Cu(L³)₂, Cu(L⁵)₂, [Cu^II(HL⁴)(NCCH₃)(OClO₃)]ClO₄, Cu^IICl(L²) and Cu^IICl(L⁷) are presented along with electrochemical and spectral (UV-Vis, FT-IR and X-band EPR) characterization for each compound. When combined with base, the isoindoline ligands in the [Cu^II(HLⁿ)(NCCH₃)(OClO₃)]ClO₄ complexes undergo deprotonation in solution that is reversible and induces UV-Vis spectral changes. Equilibrium constants for the dissociation are calculated. X-band EPR measurements in frozen solution show that the geometry of the complexes is similar to the corresponding X-ray crystallographic structures. The superoxide scavenging activity of the compounds determined from the McCord-Fridovich experiment show dependence on structural features and reduction potentials.     

Synthesis of a novel pyridine-diamino bridged diphosphine ligand and its macrocyclic metal complexes

A novel long chain diphosphine ligand with a pyridine-diamino bridge, 2,6-bis(N-benzyl-N-diphenylphosphinomethylamino)pyridine (PNP1), was prepared conveniently using the Mannich reaction of HPPh₂ with paraformaldehyde and 2,6-bis(N-benzylamino)pyridine in high yield. Reactions of the ligand with metal complexes, M(COD)Cl₂ (M = Pd, Pt), M(CH₃CN)₄ClO₄ (M = Cu, Ag) and M(CO)₆ (M = Mo, W) afforded the corresponding 10-numbered monometallic macrocyclic complexes with an uncoordinated pyridyl bridge. The monometallic chelate PdCl₂(PNP1) continued to react with Ag⁺ or Cu⁺ giving the μ-Cl bridged bicyclic metallic complex (μ-Cl)₂[PdCl(PNP1)]₂. The diphenylphosphine group coordinated with metal ion in cis-form in all the 10-numbered macrocyclic metal complexes. Ligand PNP1 and another known analogous 2,6-bis(N-diphenylphosphinoamino)pyridine (PNP2) reacted with Au(SMe₂)Cl giving the corresponding bimetallic Au₂Cl₂(PNP1) and Au₂Cl₂(PNP2), respectively. The latter bimetallic complexes continued to react with Ag⁺ and diphosphine ligand to give the corresponding bimetallic macrocyclic complexes Au₂(ligand)₂(ClO₄)₂. All the complexes were characterized and the structures of some complexes were confirmed by X-ray single crystallography determination.