Synthesis,crystal structures and characterization of iron(III) and cobalt(III) complexes bearing 2,2′-bipyridylcarboxylate ligands

Transition Metal Chemistry - The Fe(III) complex [FeIII(bpdc)(Hbpdc)] (1) (bpdc?=?2,2′-bipyridyl-6,6′-dicarboxylate and...     

Synthesis,DNA binding and antitumor activities of some novel polymer–cobalt(III) complexes containing 1,10-phenanthroline ligand

The novel water-soluble polymer–cobalt(III) complex samples, cis-[Co(phen)₂(BPEI)Cl]Cl₂ · 4H₂O (phen = 1,10-phenanthroline, BPEI = branched polyethyleneimine), with different amounts of cobalt complex content in the polymer chain, were prepared by ligand substitution method in water–ethanol medium and characterized by Infra-red, UV–Vis, ¹H NMR spectral and elemental analysis methods. The interaction of these polymer–cobalt(III)-phenanthroline complex samples with calf thymus DNA has been explored using electronic absorption spectroscopy, emission spectroscopy and gel electrophoresis techniques. The presence of multiple small size molecular binding sites, namely, the cobalt(III)–phenanthroline complex moieties, and free amino groups in a single big sized polymer molecule enhanced both the electrostatic and/or van der Waals interaction and partial intercalative bindings with calf thymus DNA. The antitumor activity of a sample of polymer–cobalt(III) complex was determined using HEp-2 cell line and different cell death indicator stains and MTT assay. Many of the cultured HEp-2 cells treated with this complex suffered loss of viability and death mostly through apoptosis as evidenced by the nuclear and cytoplasmic morphology.     

Synthesis and characterization of mercury(II)–sugar thioureas complexes

The synthesis of a novel class of mercury(II) complexes with sugar-derived bidentade isothioureido ligands, by treatment of N-acylated thioureas with an excess of yellow mercury(II) oxide in aqueous acetonitrile is reported. The 1:2 coordination stoichiometry of the complexes were confirmed by elemental analysis, mass spectrometry and NMR spectroscopy, and they were found to be consistent with a four-coordinate geometry.     

Synthesis and characterization of cobalt acrylate–melamine co-crystals

A new co-crystal of tetraaqua acrylato cobalt (II) complex and melamine, [Co(acr)₂(H₂O)₄]·4MA·2DMF (acr = acrylate, MA = melamine, DMF = dimethylformamide), has been synthesized and characterized using IR, UV-Vis, thermogravimetric analysis, and single-crystal X-ray diffraction. The complex contains discrete unities of [Co(acr)₂(H₂O)₄], melamine, and DMF linked by hydrogen bonds. Investigations evidenced that Co(II) has an octahedral stereochemistry and both acrylate ions present unidentate coordination mode. Thermal decomposition occurs in four steps and denotes that melamine is lost at high temperatures, and this indicates a greater stability that may be associated with the presence of hydrogen bonds network.

     

Synthesis and magnetic characterization of Ln(III)–Co(II) complexes with 1,10-phenanthroline ligands

Four heteronuclear complexes, [Ln₂Co₂L₁₀(H₂O)(phen)₂] · n(H₂O) (Ln = La 1, n = 2; Ln = Nd 2, Sm 3, Gd 4, n = 0; HL = α-methylacrylic acid, phen = 1,10-phenanthroline), have been synthesized and characterized by elemental analysis, IR and X-ray diffraction. The complexes with a discrete Co–Ln–Ln–Co tetranuclear molecule are isomorphous in the triclinic space group P 1 and Z = 1, in which all metal ions are bridged by bidentate α-methylacrylato groups. Magnetic measurements of 1, 2 and 3 show antiferromagnetic exchange interaction between paramagnetic centers.     

Synthesis, characterization and magnetism of μ-chloranilato bi-nuclear chromium (III) complexes

Five new chloranilato-bridged binuclear chromium (III) complexes have been synthesized and identified as [Cr2(CA)L4]-(ClO4)4[L denotes 5-methyl-1,10-phenanthroline (Me-phen); 2,9-dimethyl-1, 10-phenanthroline ( Me2-phen); 5-chloro-1,10-phenanthroline(Cl-phen); diaminoethane (en) or 1,3-diaminopropane (pn)], where CA represents the dianion of chloranilic acid. Based on elemental analyses, molar conductivity and magnetic moment of room-temperature measurements, and IR and electronic spectral studies, it is proposed that these complexes have CA-bridged structures and consist of two chromium (III) ions, each in an octahedral environment. The complexes [Cr2(CA)(Me-phen)4](ClO4)4(1) and [Cr2(CA)(Me2-phen)4](ClO4)4(2) were further characterized by variable temperature (4.2-300 K) magnetic susceptibility measurements and the observed data were successfully simulated by the equation based on the spin Hamiltonian operator, , giving the exchange parameter J = -7.8 cm-1 for (1) and J= -6.5 cm*1 for (2). This result     

Synthesis,characterization, DNA binding and cleavage activity of homoleptic zinc(II) β-oxodithioester chelate complexes

New homoleptic zinc(II) complexes, [Zn(L)₂], where L = methyl-3-hydroxy-(3-pyridyl)-2-propenedithioate L1 1, and methyl-3-hydroxy-(4-pyridyl)-2-propenedithioate L2 2, have been synthesized and characterized by elemental (C, H, and N) analysis, ESI-MS, and (IR, UV–vis, NMR) spectroscopy; the structure of 1 has been deduced by X-ray crystallography. The DNA binding and cleavage activity of the complexes have been studied. The cleavage potential of pBR322 DNA by 1 and 2 has been checked. Complex 1, which contains nitrogen of the pyridine group in the 3-position enhances DNA cleavage potential in the presence of ascorbic acid; however, the complex is protective against DNA cleavage in the presence of DMSO or H₂O₂. Also, 1 causes cytotoxicity against the MCF-7 breast cancer cell line. The efficient cytotoxic activity and DNA cleavage ability of 1 in the presence of ascorbic acid shows its potential anticancer properties and the need for further investigations of its potential as an anticancer drug.     

Synthesis, characterization, and electron transfer reaction of some surfactant–cobalt(III) complex ions

Abstract  

The surfactant complex ion cis-[Co(tmd)₂(C₁₂H₂₅NH₂)₂]³⁺ (tmd = 1,3-propanediamine, C₁₂H₂₅NH₂ = dodecylamine) has been synthesized and characterized by elemental analysis and spectral data. In addition we have determined the critical micelle concentration of the surfactant–cobalt(III) complex and studied the kinetics and mechanism of the complex with ferrocyanide anion. The reaction is found to be second order, and the second-order rate constant increases with increasing initial concentration of the surfactant–cobalt(III) complex due to the presence of self-micelles formed by the complex itself. The thermodynamic parameters were determined. The results have been analyzed.     

Synthesis and structures of two uranyl β-diketonate complexes [UO2(DBM)2(DEDPU)] and [UO2(PMBP)2(DEDPU)]

Two new uranyl β-diketonate complexes [UO₂(DBM)₂(DEDPU)] (1) and [UO₂(PMBP)₂(DEDPU)](CH₃C₆H₅)_0.5 (2), (HDBM?=?dibenzoylmethane, HPMBP?=?1-phenyl-3-methyl-4-benzoyl-5-pyrazolone, DEDPU?=?N,N′-diethyl-N,N′-diphenylurea) were synthesized and characterized. The coordination geometries of the uranyl atoms in 1 and 2 are distorted pentagonal bipyramidal, coordinated by one oxygen atom of DBDPU molecule and four oxygen atoms of two chelating DBM molecules in 1 and PMBP molecules in 2.     

Synthesis,characterization and antitumour activity of uracil and uracil–histidine complexes with metal(III) ions

Complexes of the[Al(L-H)(OH)Cl],[M(L-H)(H2O)2- (OH)Cl] and [M(L-H)(L-H)(H2O)Cl] type, where L = uracil (URL); L = histidine (HISD); M = CrIII or FeIII and M = AlIII, CrIII or FeIII were synthesized and characterized. The complexes are polymers, with high decomposition points and are insoluble in water and common organic solvents. Uracil is coordinated to the metal ion through the O atom of C(4)-O and the N atom of N(1), while histidine coordinates through the O atom of -CO2– and the N atom of the -NH2 groups. The eff values, electronic spectral bands and e.s.r. spectra suggest a polymeric six coordinate spin-free octahedral stereochemistry for the CrIII and FeIII complexes. The in vivo and in vitro antitumour activity results indicate that CrIII and FeIII complexes have significant activity against P815 murine mastocytoma but AlIII complexes show poor activity.     

Synthesis and characterization of platinum(II) and (IV) complexes containing hexamethyleneimine ligand: crystal structure of [PtII(hexamethyleneimine)2(cyclobutanedicarboxylato)]·H2O

A series of new platinum(II) and platinum(IV) complexes of the type [Pt^II(HMI)₂X] (where HMI=hexamethyleneimine, X=dichloro, sulfato, 1,1-cyclobutanedicarboxylato [CBDCA], oxalato, methylmalonato, or tatronato) and [Pt^IV(HMI)₂Y₂Cl₂] (where Y=hydroxo, acetato, or chloro) were synthesized and characterized by infrared (IR) spectroscopy, ¹³C and ¹⁹⁵Pt nuclear magnetic resonance (NMR) spectroscopy and elemental analysis. Among the complexes synthesized, [Pt^II(hexamethyleneimine)₂(1,1-cyclobutanedicarboxylato)]·H₂O was examined by single-crystal X-ray diffraction. The slightly distorted square planar coordination environment of the platinum metal includes the amino group of the hexamethyleneimine (HMI) molecule and the oxygen atoms of the carboxylato ligand. The cyclobutanedicarboxylic acid (CBDCA) molecule adopts six-member chelating rings with platinum. Hydrogen bonding plays an important part in holding the crystal lattice together.     

Kinetic study of the protonations and substitutions of different cobalt(III)–nta complexes

The behaviour of the Cobalt(III)–nta (nta = nitrilotriacetate) system in an acidic medium was investigated. The acid dissociation constant, pK _a1, of [(nta)(H₂O)Co(-OH)Co(H₂O)(nta)]^– was determined as 3.09(3) and the pK _a of the cis-[Co(nta)(H₂O)₂]/[Co(nta)(H₂O)(OH)]^– equilibrium was determined as 6.71(1). cis-[Co(nta)(H₂O)₂] undergoes ring-opening upon acidification below pH = 2.0. The formation of [Co( ³-nta)(H₂O)₃]⁺ was also studied. The substitutions between cis-[Co(nta)(H₂O)₂] and NCS^– ions were investigated in the pH = 2–7 ranges. [Co(nta) (H₂O)(OH)]^– reacts ca. 70 times faster at 24.7 °C with NCS^– ions than cis-[Co(nta)(H₂O)₂], indicating a cis-labilising effect of the OH^– ligand.     

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 and structures of two cobalt complexes [NaCoII(NTA)(H2O)] n and NH4[CoIII(IDA)2] · 2H2O

Two cobalt complexes [NaCo^II(nta)(H₂O)] _n (H₃nta?=?nitrilotriacetic acid) (1) and NH₄[Co^III(ida)₂]?·?2H₂O (H₂ida?=?iminodiacetic acid) (2) have been synthesized and characterized by single-crystal X-ray diffraction analysis. Compound 1 crystallizes in the orthorhombic system, space group P2₁2₁2₁ with a?=?7.9770(12)?Å, b?=?9.7613(15)?Å, c?=?12.1945(18)?Å, V?=?949.5(2)?ų, Z?=?4, and R ₁?=?0.0705 for 1597 observed reflections. Compound 2 crystallizes in the monoclinic system, space group P2(1)/c with a?=?5.1801(3)?Å, b?=?11.2073(6)?Å, c?=?12.2891(7)?Å, V?=?707.09(7)?ų, Z?=?2, and R ₁?=?0.0349 for 1143 observed reflections. In compound 1, the Co is coordinated by a nitrogen and five oxygen atoms in a distorted octahedral geometry {CoNO₅}, and the Na is coordinated by one water molecule and four carboxyl oxygen atoms in slightly distorted square pyramidal geometry. The entire structure shows a three-dimensional network. In compound 2, Co atom is equatorially coordinated by two ida ligands in a distorted octahedral geometry {CoN₂O₄}. The discrete [Co(ida)₂]^2? anions are linked by hydrogen bonding to a three-dimensional supramolecular network.     

Synthesis,characterization, and biocide activity of new dithiocarbamate-based complexes of In(III), Ga(III), and Bi(III) – Part III

In this work, we describe the syntheses, characterization, and antifungal activity of [In{S₂CNR(R¹)}₃] (1), [Ga{S₂CNR(R¹)}₃] (2), [Bi{S₂CNR(R¹)}₃] (3), [In{S₂CNR(R²)}₃] (4), [Ga{S₂CNR(R²)}₃] (5), and [Bi{S₂CNR(R²)}₃] (6) {R?=?Me; R¹?=?CH₂CH(OMe)₂; and R²?=?2-methyl-1,3-dioxolane}. All complexes have been characterized using infrared and ¹H and ¹³C spectroscopy, and the structures of 1, 3, 4, and 6 have been authenticated by X-ray diffraction. The In(III)–dithiocarbamate bonding scheme depicts a distorted octahedral with asymmetric In(III)–S bonds and S–In–S angles. A pentagonal bipyramid is observed for the corresponding Bi(III) complexes with intermolecular Bi–S associations through the lone pair of electrons. The antifungal activities of 1–6 have been screened against Aspergillus niger, Aspergillus parasiticus, and Penicillium citrinum, and the results have been compared with those of nystatin and miconazole nitrate, as control drugs.     

Synthesis and characterization of a monomeric and a dihydroxo-bridged dimeric complexes of iron(III) with α-benzoinoxime

The reaction of α-benzoinoxime, H₂BNO with FeCl₃ in the presence of Et₃N as a base gives the mononuclear Fe(III) complex, Fe(HBNO)₃ (1). Treatment of 1 with a methanolic solution of KOH at room temperature leads to a dinuclear Fe(III)–Fe(III) complex, [Fe(HBNO)₂OH]₂ (2). The complexes were initially characterized on the basis of their elemental, mass and thermal analyses. The IR studies were useful in assigning the coordination mode of the benzoinoxime ligand to the iron metal. In addition, the presence of a hydroxo-bridge in the dimeric complex 2 is inferred from the IR spectral studies. Room-temperature Mössbauer studies indicated octahedral, high-spin iron(III). Variable-temperature magnetic susceptibility measurements supported the existence of the μ-dihydroxo-bridging structure core, Fe^III(μ-OH)₂Fe^III in the dinuclear complex 2. Theoretical modelling of the magnetic data indicated a weak antiferromagnetic spin exchange between the iron(III) centers (J = −8.35 cm⁻¹, g = 2.01, ρ = 0.02 and TIP = 1.7 × 10⁻⁴ cm³ mol⁻¹ for H = −2JS₁ · S₂). The electronic spectra of the complexes revealed two bands due to d–d transitions and one band assignable to an oxygen (p_π) → Fe(d_π∗) LMCT transition observed in each complex. An additional charge-transfer transition, assignable to μ-hydroxo(p_π) → Fe(d_π∗), was observed for the dimeric complex 2. The structural and vibrational behaviors of these complexes have been elucidated with quantum mechanical methods.     

Autocatalytic O2 cleavage by an OCO3 trianionic pincer Cr(III) complex: isolation and characterization of the autocatalytic intermediate [Cr(IV)]2(μ-O) dimer

Synthetic and kinetic experiments designed to probe the mechanism of O(2) activation by the trianionic pincer chromium(III) complex [(t)BuOCO]Cr(III)(THF)(3) (1) (where (t)BuOCO = [2,6-((t)BuC(6)H(3)O)(2)C(6)H(3)](3-), THF = tetrahydrofuran) are described. Whereas analogous porphyrin and corrole oxidation catalysts can become inactive toward O(2) activation upon dimerization (forming a μ-oxo species) or product inhibition, complex 1 becomes more active toward O(2) activation when dimerized. The product from O(2) activation, [(t)BuOCO]Cr(V)(O)(THF) (2), catalyzes the oxidation of 1 via formation of the μ-O dimer {[(t)BuOCO]Cr(IV)(THF)}(2)(μ-O) (3). Complex 3 exists in equilibrium with 1 and 2 and thus could not be isolated in pure form. However, single crystals of 3 and 1 co-deposit, and the molecular stucture of 3 was determined using single-crystal X-ray crystallography methods. Variable (9.5, 35, and 240 GHz) frequency electron paramagnetic resonance spectroscopy supports the assignment of complex 3 as a Cr(IV)-O-Cr(IV) dimer, with a high (S = 2) spin ground state, based on detailed computer simulations. Complex 3 is the first conclusively assigned example of a complex containing a Cr(IV) dimer; its spin Hamiltonian parameters are g(iso) = 1.976, D = 2400 G, and E = 750 G. The reaction of 1 with O(2) was monitored by UV-visible spectrophotometry, and the kinetic orders of the reagents were determined. The reaction does not exhibit first-order behavior with respect to the concentrations of complex 1 and O(2). Altering the THF concentration reveals an inverse order behavior in THF. A proposed autocatalytic mechanism, with 3 as the key intermediate, was employed in numerical simulations of concentration versus time decay plots, and the individual rate constants were calculated. The simulations agree well with the experimental observations. The acceleration is not unique to 2; for example, the presence of OPPh(3) accelerates O(2) activation by forming the five-coordinate complex trans-[(t)BuOCO]Cr(III)(OPPh(3))(2) (4).