Synthesis,DNA binding and cleavage studies of the copper(Ⅱ) complexes of PNA-cyclen conjugates

Two dinucleotide PNA-cyclen copper(II) complexes with α-PNA (P1) and classical PNA (P2) backbones were synthesized and characterized.The interactions between title complexes and DNA were investigated under physiological conditions.Fluorescence studies indicate that the binding ability of complex P1 to CT-DNA is as twice as that of P2.DNA melting experiments were also carried out and the results show that ΔTm caused by P1 is higher than that caused by P2.Agarose gel electrophoresis experiments demonstrate th...     

Synthesis,characterization, crystal structure,and DNA binding of two copper(II)–hydrazone complexes

Two new Cu(II)–hydrazone complexes, [Cu(L)(Hbpe)ClO₄]·ClO₄·[Cu(L)Cl] (1) and [Cu(HL)₂]·1.5ClO₄·0.5OH (2) (where HL?=?(E)-N′-(1-(pyridine-2-yl)ethylidene)benzohydrazide and bpe = trans-1-(2-pyridyl)-2-(4-pyridyl)ethylene), have been synthesized and characterized by physicochemical methods. The structures of the complexes have been established by single-crystal X-ray diffraction direct methods, which reveal that the metal ions have distorted square-pyramidal and square-planar geometries in 1, and a distorted octahedral geometry in 2. DNA binding of HL, 1, and 2, performed by UV–vis titration in tris-buffer medium, yielded binding constants, which are 9.5 × 10³, 1.88 × 10⁴, and 4.66 × 10⁴ M^?1, respectively. Viscosity measurements suggest a surface or groove-binding mode of interaction between CT-DNA with HL, 1, and 2.     

Synthesis, and characterization of ruthenium(II) polypyridyl complexes containing α-amino acids and its DNA binding behavior

Reactivity of the ruthenium complexes [Ru(κ³-tptz)(PPh₃)Cl₂] (1) and [Ru(κ³-tpy)(PPh₃)Cl₂] (2) [tptz = 2,4,6-tris(2-pyridyl)-1,3,5-triazine; tpy = 2,2′:6′,2″-terpyridine] with several α-amino acids [glycine (gly); leucine (leu); isoleucine (isoleu); valine (val); tyrosine (tyr); proline (pro) and phenylalanine (phe)] have been investigated. Cationic complexes with the general formulations [Ru(κ³-L)(κ²-L″)(PPh₃)]⁺ (L = tptz or tpy; L″ = gly, leu, isoleu, val, tyr, pro, and phe] have been isolated as tetrafluoroborate salts. The resulting complexes have been thoroughly characterized by analytical, spectral and electrochemical studies. Molecular structures of the representative complexes [Ru(κ³-tptz)(val)(PPh₃)]BF₄ (6)_, [Ru(κ³-tpy)(leu)(PPh₃)]BF₄ (10) and [Ru(κ³-tpy)(tyr)(PPh₃)]BF₄ (13) have been determined crystallographically. The complexes [Ru(κ³-tptz)(leu)(PPh₃)]BF₄ (4), [Ru(κ³-tptz)(val)(PPh₃)]BF₄ (6), [Ru(κ³-tpy)(leu)(PPh₃)]BF₄ (10) [Ru(κ³-tpy)(tyr)(PPh₃)] BF₄·3H₂O (13) exhibited DNA binding behavior and acted as mild Topo II inhibitors (10-40%). The complexes also inhibited heme polymerase activity of the malarial parasite Plasmodium yoelii lysate.     

Tetra(μ3-hydroxo) bridged copper(II) tetranuclear cubane complexes: synthesis,crystal structure,and DNA binding studies

The tridentate Schiff base H₂L was synthesized by the condensation of equimolar amount of 1-amino-2-propanol and salicylaldehyde. The reaction of H₂L with an equimolar amount of Cu(CH₃COO)₂·H₂O in methanol leads to the formation of the tetranuclear Cu₄L₄, 1. However, reaction of equimolar amount of H₂L, copper(II) acetate, and 2,4,6-trimethylaniline in methanol forms a mixture of products which includes a discrete mononuclear complex Cu(L′)₂, 2m (where HL′ is a bidentate ligand), in addition to the tetranuclear Cu₄L₄ species, 2c. In both tetranuclear cubane species, the tridentate H₂L is both a chelating and a bridging ligand, after deprotonation of the enolic and the phenolic OH. The copper(II) centers are five-coordinate with a [N, O₄] donor set from the ligands. The coordination geometry about each copper is distorted square pyramidal with one nitrogen and two oxygen from one ligand and two oxygen from adjacent ligands in the next unit of the cubane. In mononuclear 2m, the ligand is bidentate and the coordination geometry around copper(II) is square planar. The absorption spectra strongly suggest that tetranuclear 1 interacts with CT-DNA.     

Synthesis and cytotoxicity of dinuclear platinum(Ⅱ) complexes of (1S, 3S)-1, 2, 3, 4-tetrahydroisoquinolines

A series of novel dinuclear platinum(Ⅱ) complexes with (1S, 3S)-1,2,3,4-tetrahydroisoquinolines as the ligands were synthesized as potential anticancer agents in several steps starting from commercially available L-DOPA. The cytotoxicities of the series of dinuclear platinum(Ⅱ) complexes of tetrahydroisoquinoline were tested against HCT-8, BEL-7402, A2780, MCF-7, Hela, A549 and BGC-823 cell lines by the MTT test. These complexes showed selective inhibition activity against cisplatin-insensitive cell line Skov3.     

Metal complexes of porphyrin–anthraquinone hybrids: DNA binding and photocleavage specificities

A cationic porphyrin–anthraquinone hybrid and its Zn(II), Cu(II), Co(III), and Mn(III) complexes were synthesized and their interactions with duplex DNA were studied using a combination of absorption, fluorescence titration, circular dichroism spectroscopy, thermal DNA denaturation, viscosity measurements, gel electrophoresis, and gas chromatography. Metal coordination induces intermolecular steric hindrance and thus the metal hybrids have smaller DNA binding affinities than the free base hybrid; the steric hindrance could relax the intermolecular aggregation and increase ¹O₂ generation of the metal hybrids. The DNA photocleavage abilities of these hybrids were investigated.     

Synthesis, spectroscopic, powder X-ray diffraction and DNA binding studies on copper(II) complexes of 4,4′-diaminodiphenyl sulfone

Four new Cu(II) complexes of 4,4??-diaminodiphenyl sulfone (DDS) with different anions (chloride, sulfate, nitrate or acetate) were synthesized and characterized by elemental analysis, electronic absorption, IR, magnetic moment, thermal analysis and powder X-ray diffraction studies. It was found that the pure DDS and complex [Cu₂(DDS)₂(NO₃)₂].(NO₃)₂ (3) crystallize in orthorhombic system while the complexes [Cu₂(DDS)₂].Cl₄ (1), [Cu₂(DDS)₂].(SO₄)₂ (2), and [Cu₂(DDS)₂].(CH₃COO)₄ (4) crystallize in monoclinic system. The crystallite sizes of complexes have smaller values as compared to pure DDS. Infrared studies suggest that the coordination of NH₂ of DDS with Cu(II) ion. The binding of the complexes with calf thymus (CT) DNA was investigated by electronic absorption titration, fluorescence measurements and DNA thermal denaturation. The spectroscopic studies together with the DNA melting studies indicated that the complexes may bind to CT-DNA in a non-intercalative mode.     

Synthesis, structure and characterization of binuclear copper(Ⅱ) complexes

At room temperature, dibenzoyl peroxide undergoes oxidative addition reaction with metallic copper powder and pyridine N-oxide (triphenylphosphine oxide or 2,9-dimethyl-4,7-diphenyl-1,10-phenanthrolin) which affords the last products as binuclear copper(II) complexes, [Cu(C5H5NO)-(C6H5COO)2]2(1), [Cu(OPPh3)(C6H5COO)2]2(2) and [Cu(C6H5COO)(C26H2oN2)](3, C26H2oN2 is 2,9-dimethyl-4,7-diphenyl-1,10-phenanthrolin). The structure of the complexes were characterized by elemental analyses, IR spectra, TG-DTA and magnetic property. Crystals(1) are triclinic, space group P1,a=0.92617(36),b=1.06973(17), c=1.08813(29) nm, a=59.60(2)°, β=74.83(3)°,γ=72.80(2)°, V=0.880 nm3, Dc=1.520 g/cm3, Z=1, R=0.044, Rw=0.048, Mr=805.78, 3477 reflections with I > 3σ(I). Each copper(Ⅱ) ion is coordinated by two bridging bidentate benzoate ligands and one pyridine N-oxide or triphenylphosphine oxide to form dimeric binuclear molecules. The structure of the compound(1) shows a clear centre of symmetry.     

Hydrocarbon (π- and σ-) complexes of nickel,palladium and platinum: Synthesis,reactivity and applications

With the exception of metallocenes, transition metal complexes with hydrocarbon ligands only are rare. However, complexes of this type containing Group 10 metals are known and have been shown to be quite stable. These complexes are versatile precursors for many organometallic compounds. In addition, such compounds can play an important role in many reactions including C–H or C–C activation reactions and have useful applications in the thermal and photochemical production of metal films by chemical vapour deposition (CVD). The present review summarizes the synthesis, properties and chemistry of hydrocarbon complexes of Group 10 metals of the type L_nM or L_nMR₁R₂ (where L_n = σ- or π-hydrocarbon ligands; M = Ni, Pd and Pt; R₁, R₂ = σ-hydrocarbon ligands) without the involvement of any hetero donor ligands such as N, P, O and S in the metal coordination spheres.     

Half-sandwich η-benzene Ru(II) complexes of pyridylpyrazole and pyridylimidazole ligands: Synthesis, spectra, and structure

New series of half-sandwich ruthenium(II) complexes supported by a group of bidentate pyridylpyrazole and pyridylimidazole ligands [(η⁶-C₆H₆)Ru(L²)Cl][PF₆] (1), [(η⁶-C₆H₆)Ru(HL³)Cl][PF₆] (2), [(η⁶-C₆H₆)Ru(L⁴)Cl][PF₆] (3), and [(η⁶-C₆H₆)Ru(HL⁵)Cl][PF₆] (4) [L², 2-[3-(4-chlorophenyl)pyrazol-1-ylmethyl]pyridine; HL³, 3-(2-pyridyl)pyrazole; L⁴, 1-benzyl-[3-(2′-pyridyl)]pyrazole; HL⁵, 2-(1-imidazol-2-yl)pyridine] are reported. The molecular structures of 1-4 both in the solid state by X-ray crystallography and in solution using ¹H NMR spectroscopy have been elucidated. Further, the crystal packing in the complexes is stabilized by C-H?X (X = Cl and π), N-H?Cl, and π-π interactions.     

Binuclear copper(II) complexes of 1-amidino-O-alkylurea (alkyl = n-propyl,n-butyl,or i-butyl) and vanadate: an EPR study

Five new complexes of bis(1-amidino-O-alkylurea)Cu(II)vanadate where alkyl?=?methyl, ethyl, n-propyl, n-butyl or i-butyl have been synthesized by reaction of ammonium metavanadate with bis(1-amidino-O-alkylurea)Cu(II)perchlorate complexes. Electron paramagnetic resonance (EPR) spectra of bis(1-amidino-O-n-propylurea)Cu(II)vanadate (1), bis(1-amidino-O-n-butylurea)Cu(II)vanadate (2) and bis(1-amidino-O-i-butylurea)Cu(II)vanadate (3) gave half-field signal (ΔM _s?=?±2) ca 1623G, in addition to fine structure due to zero field splitting (ZFS) characteristics of the S?=?1 system. From the observed ZFS the average Cu–Cu distance was estimated. The isotropic exchange constant J was evaluated by recording EPR spectra at different temperatures. The photoacoustic signal of the complexes indicated square-planar geometry around Cu²⁺. X-ray powder diffraction studies on 2 suggested orthorhombic structure with unit cell dimensions a?=?21.11?Å, b?=?24.11?Å, c?=?27.11?Å, α?=?β?=?γ?=?90°. The crystal structure of bis(1-amidino-O-n-butylurea)Cu(II)perchlorate is also reported.     

Synthesis, characterization, DNA binding and antimicrobial studies on bis(1-amidino-O-2-alkoxyethylurea) copper(II) chloride complexes (alkoxy?=?methoxy or ethoxy)

Copper(II) complexes of [Cu(II)(1-amidino-O-2-methoxyethylurea)₂]Cl₂ (1) and [Cu(II)(1-amidino-O-2-ethoxyethylurea)₂]Cl₂ (2) have been synthesized and characterized by elemental analysis, magnetic moment, conductance, thermal analysis, IR, UV, powdered XRD and EPR spectral studies. The trend in g values g _||?>?g _???>?2.0023 in the EPR spectra of the complexes suggest that the unpaired electron on copper(II) ion has ${d_{x}}^2 - {{}_{y}}^2$ character and the complexes have square planar structure which is also supported by electronic absorption spectral studies. The bonding parameters of these complexes in DMF have been calculated based on the EPR and electronic spectral data. The complexes (1) and (2) exhibit K _||?>?K _?? which indicates the presence of significant out-of-plane ?? bonding. Powdered XRD spectral patterns show that complexes crystallize in a monoclinic system. The binding of the complexes with calf thymus DNA was investigated by absorption and emission spectroscopy, viscosity measurements, DNA melting and cyclic voltammetric studies. DNA interaction studies show that the complexes bind to calf thymus DNA in a non-intercalative mode. The two complexes exhibit growth inhibitory activity against pathogenic bacteria, viz., Escherichia coli, Klebsiella pneumoniae sub sp. Pneumoniae, Proteus mirabilis.     

Spectroscopic,electrocatalytic, and photoelectrochemical characteristics of mixed-ligand bis(β-dicarbonylato) phthalocyanine complexes of zirconium(IV) and hafnium(IV)

The electronic absorption (EAS) and fluorescence spectra and electrocatalytic and photoelectrochemical characteristics of mixed-ligand complexes of zirconium(IV) and hafnium(IV) based on phthalocyanines in solutions and in thin films were investigated. It was established that a significant bathochromic shift of the Q band and redistribution of the intensities in the absorption bands are observed in the electronic absorption spectra. It was shown that films of the synthesized compounds are promising for use as photosensitizers and electrochemical sensors for oxygen in solution. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 44, No. 3, pp. 133–137, May–June, 2008.     

Dielectric,electro-optic and infrared and 1H NMR spectral properties of methyl- and t-butyl-substituted (η6-benzene)tricarbonylchromium(0) complexes: a study of solvent effects

Dipole moment, microwave dielectric absorption, electric birefringence and infrared and ¹H NMR spectral data are presented for [Cr(CO)₃(η⁶-C₆H₆)] and for some of its methyl- and t-butyl-substituted derivatives in the non-dipolar solvents, cyclohexane, benzene and dioxane. Atomic polarisations for these complexes are shown to be negligibly small. Specific interactions are shown to occur between dioxane or benzene solvent molecules and the coordinated arene which acts as an electrophile. The effects on such interactions of progressive methyl or t-butyl group insertion on the arene nucleus are studied. In 1,3,5-tri-t-butylbenzenetricarbonylchromium(0), “face-to-face” associations between the arene ligand and solvating benzene are sterically inhibited. Direct complexation with chromium is shown to be improbable with these solvents. The solute polarisability tensor of [Cr(CO)₃(η⁶-C₆H₆)], unlike the dipole moment vector, is not changed by interaction with dioxane. With methyl or t-butyl substitution, the solute polarisability anisotropy in dioxane tends to decrease, relative to that in cyclohexane. Electric birefringences and ¹H NMR chemical shifts are interpreted in terms of transient stereospecific solute-benzene associations additional to “face-to-face” charge-transfer interactions. Benzene-induced upfield shifts or aryl protons (ASIS) decrease in magnitude with progressive methyl or t-butyl substitution.     

Volatile complexes of Pd(II) with methoxy-β-iminoketones: Synthesis,properties, and crystal and molecular structure

This paper describes a procedure for the synthesis of two new volatile complexes, Pd(L¹)₂ and Pd(L²)₂, from sterically hindered methoxy-β-iminoketones, where HL¹ = C(CH₃)₂(OCH₃)-C(NH)-CH₂-C(O)-C(CH₃)₃; HL² = C(CH₃)₂(OCH₃)-C(NH)-CH₂-C(O)-CH(CH₃)₂. Element analysis and IR spectral data are given. The results of full X-ray crystal structure analysis of the complexes are reported. The compounds have molecular structures; the crystals of the complexes have different symmetry groups and unit cell dimensions. The Pd(L¹)₂ complex molecule has a nonplanar structure; the Pd(L²)₂ complex has a cis-structure. The geometrical characteristics obtained for the coordination units are as follows: the Pd-O and Pd-N bond lengths and N-Pd-O chelate angles were estimated at 1.960 Å, 93.7° for Pd(L¹)₂, and 1.984 Å, 1.976 Å, 92.4° for Pd(L²)₂.     

Diaminodithioether complexes of nickel(II) and palladium(II): A unique case of dealkylation of S,S′-thioether

Summary Nickel(II) and palladium(II) complexes of the 1,3-di(o-aminophenylthio) propane (H₂L¹) and 1,2-di(o-aminophenylthio)xylene (H₂L²) ligands have been prepared and characterized. The hydrobromide salt of H₂L¹ gave a 12 ligand-metal complex of Pd^II, whereas free H₂L¹ formed the usual 1:1 species. The reaction of Na₂PdCl₄ with H₂L² resulted in S,S-dealkylation of the ligand and formation of a mononuclear complex of the corresponding thiol, i.e. 2-aminobenzenethiol. NiCl₂, NiBr₂ and Ni(ClO₄)₂ did not react directly with H₂L². Ni^II is a fairly hard ion and therefore does not coordinate to the soft thioether moiety in H₂L² in the absence of soft anions which symbiotically motivate Ni^II to act as a soft acceptor. It thus does not react with H₂L² in the presence of hard ions such as Cl^–, Br^- and ClO ₄ ^– , but, the in situ reaction of the constituents produced the tetrahedral Ni^II complex, contrary to earlier reports of similar types of octahedral species.     

Synthesis,characterization, and biological evaluation of silver(I) complexes of N′-(1-(pyrazin-2-yl)ethylidene)picolinohydrazide

Three Ag⁺ complexes, [Ag(L)(NO₃)]_n (1), {[Ag(L)]·SbF₆·CH₂Cl₂}_n (2), and {[Ag(L)]·SO₃CF₃·CHCl₃}_n (3), based on a hydrazone ligand L have been obtained (L = N′-(1-(pyrazin-2-yl)ethylidene)picolinohydrazide) and characterized. Complexes 1–3 all show 1-D chain-like structures. Their antibacterial activity and interaction with serum albumin were investigated. These results indicate that these complexes show good antibacterial activities and binding affinity to serum albumin.