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1.
Pd(BHEP)Cl2 was synthesized and characterized (BHEP = 1,4-bis(2-hydroxyethyl)piperazine). The complex decomposes in two steps, leaving a residue of palladium metal. Amino acid ester (L) reacts with [Pd(BHEP)(H2O)2]2+ (BHEP = 1,4-bis(2-hydroxyethyl)piperazine), giving mixed-ligand complexes, [Pd(BHEP)L]2+. The kinetics of hydrolysis of [Pd(BHEP)L]2+ have been studied by pH-stat technique, and rate constants were obtained. Rate acceleration observed for glycine methyl ester is high. The effect with methionine methyl ester is much less marked, as the mixed-ligand complexes with these ligands do not involve alkoxycarbonyl donors. Possible mechanisms for these reactions are considered.  相似文献   

2.
The complexes [Ni(L1)(pyc)2]·2H2O (1) (L1 = C-meso-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane; Hpyc = pyrazinecarboxylic acid) and [Cu(L2)(H-cpdc)] (2) (L2 = 3,14-dimethyl-2,6,13,17-tetraazatricyclo[14,4,01.18,07.12]docosane; H2-cpdc = cyclopropanedicarboxylic acid) have been synthesized and structurally characterized. The crystal structure of complex 1 shows a distorted octahedral coordination geometry around the nickel(II) center, with four secondary amines in the equatorial positions and two nitrogen atoms of the pyc? ligands in the trans positions. In complex 2, the coordination environment around the copper(II) center is a Jahn–Teller distorted octahedron with four Cu–N bonds and two axial Cu–O bonds. The electronic spectra, electrochemical and TGA behavior of the complexes are significantly affected by the nature of the axial pyc? and H-cpdc? ligands.  相似文献   

3.
Four linear trinuclear transition metal complexes have been prepared and characterized. The complexes [MII(MeOH)4][FeIII(L)2]2·2MeOH (M = Fe (1) or Ni (2)), [CoII(EtOH)2(H2O)2][FeIII(L)2]2·2EtOH (3), and [MnII(phen)2][MnIII(L)2]2·4MeOH (4) (H2L = ((2-carboxyphenyl)azo)-benzaldoxime, phen = 1,10-phenanthroline) possesses a similar synanti carboxylate-bridged structure. The terminal Fe(III) or Mn(III) ions are low spin, and the central M(II) ions are high spin. Magnetic measurements show that antiferromagnetic interactions were present between the adjacent metal ions via the synanti carboxylate bridges. The antiferromagnetic coupling between low-spin Fe(III) and Ni(II) is unusual, which has been tentatively assigned to the structural distortion of Fe(III).  相似文献   

4.
Mononuclear copper(II), cobalt(II) and nickel(II) complexes of cetirizine (CTZ = 2-[2-[4-[(4-chlorophenyl)phenyl methyl]-piperazine-1-yl]-ethoxy]acetic acid) in the presence of 2-aminomethyl-benzimidazole·2HCl (AMBI), as a representative example of heterocyclic bases, were synthesized and studied by different physical techniques. All mixed-ligand complexes have been fully characterized with the help of elemental analyses, molecular weight determinations, molar conductance, magnetic moments and spectroscopic data. The formulae of the isolated complexes are [M(AMBI)(CTZ)(NO3)(H2O)2nH2O where AMBI is the neutral bidentate 2-aminomethylbenzimidazole, CTZ the deprotonated cetirizine and n = 1 for Co(II) or 0 for Cu(II) and Ni(II) complexes. The measured molar conductance values in DMSO indicate that the complexes are non-electrolytes. The formation equilibria of the ternary complexes have been investigated. Ternary complexes are formed by a simultaneous mechanism. Stoichiometry and stability constants for the complexes formed are reported. The concentration distribution of the complexes in solution was evaluated as a function of pH. The thermodynamic parameters were calculated from the temperature dependence of the equilibrium constants and are discussed. The synthesized metal chelates have been screened for their antimicrobial activities against the selected types of Gram-positive (G+) and Gram-negative (G?) bacteria. They were found to be more active against Gram positive than Gram negative bacteria. The antimicrobial activity in terms of metal ions obeys this order: Cu(II) > Ni(II) > Co(II).  相似文献   

5.
Salicylaldehyde-4-methylthiosemicarbazone (H2MTSali) has been prepared via the condensation reaction of 4-methyl-3-thiosemicarbazide and salicylaldehyde. Four new mixed-ligand copper(II) and nickel(II) complexes with a general formula [M(MTSali)L] (M = Cu2+ or Ni2+; L = co-ligand) were synthesized, where L is either imidazole (im) or benzimidazole (bzim). The Schiff base and its mixed-ligand complexes were characterized by IR and UV/Vis spectroscopy, and the complexes by molar conductivity and magnetic susceptibility measurements. The spectroscopic data indicated that the Schiff base behaves as a tridentate ONS donor ligand coordinating via the phenoxide-oxygen, azomethine-nitrogen, and thiolate-sulphur atoms. Magnetic data indicate a square planar environment for the nickel(II) complexes while molar conductance values indicate that the metal complexes are essentially non-electrolytes in DMSO solution. X-ray crystallography shows Cu(MTSali)bzim (1) and Ni(MTSali)bzim (3) to be isostructural, with the metal(II) ions being coordinated by a N2OS donor set that defines an approximate square planar geometry; in both cases, the benzimidazole is splayed with respect to the coordination plane. The copper(II) complexes were active against MDA-MB-231 and MCF-7 breast cancer cell lines, more so than H2MTSali, whereas the nickel(II) complexes were inactive.  相似文献   

6.
Reaction of thiosemicarbazones of salicylaldehyde and 2-hydroxyacetophenone (H2L1 and H2L2) with [Ir(PPh3)3Cl] affords complexes of type [Ir(PPh3)2(L)(H)] (L = L1 or L2) in ethanol. A similar reaction carried out in toluene affords the [Ir(PPh3)2(L)(H)] complexes along with complexes of type [Ir(PPh3)2(L)Cl], where a chloride is coordinated to iridium instead of the hydride. The structure of the [Ir(PPh3)2(L2)(H)] and [Ir(PPh3)2(L2)Cl] complexes has been determined by X-ray crystallography. Crystal data for [Ir(PPh3)2(L2)(H)]: space group, P21/c; crystal system, monoclinic; a=12.110(2) Å, b=17.983(4) Å, c=18.437(4) Å, β=103.42(3)°, Z=4; R 1=0.0591, wR 2=0.1107. Crystal data for [Ir(PPh3)2(L2)Cl]: space group, P21/c; crystal system, monoclinic; a=17.9374(11) Å, b=19.2570(10) Å, c=24.9135(16) Å, β=108.145(5)°, Z=4; R 1=0.0463, wR 2=0.0901. In all the complexes the thiosemicarbazones are coordinated to the metal center as dianionic tridentate O, N, S-donors and the two triphenylphosphines are trans. The complexes are diamagnetic (low-spin d? 6, S=0) and show intense MLCT transitions in the visible region. Cyclic voltammetry on all the [Ir(PPh3)2(L)(H)] and [Ir(PPh3)2(L)Cl] complexes shows a quasi-reversible Ir(III)–Ir(IV) oxidation within 0.55–0.78 V vs. SCE followed by an irreversible oxidation of the thiosemicarbazone within 0.91–1.27 V vs. SCE. An irreversible reduction of the thiosemicarbazone is also observed within ?1.10 to ?1.23 V vs. SCE.  相似文献   

7.
Monometallic trivalent complexes of iron were synthesized by reaction between N, O type donor ligands (L) or (L′) and metal salt in a 1:2 (metal:ligand) molar ratio. Structure and composition of metal complexes were evaluated by elemental analysis, conductance measurements, magnetic moment measurements, and various spectroscopic studies viz. FTIR, UV–visible, and ESI–MS. Analytical and molar conductance data are consistent with the formulation of complexes as [Fe(L)2X2]·X and [Fe(L′)2X2]·X (where; L = Hydrazine carboxylic acid ethyl ester, L′ = Hydrazine carboxylic acid tert-butyl ester and X = Cl?, Br? or NO3 ?) due to their 1:1 electrolytic nature. IR spectral data revealed bi-dentate coordination behavior of ligands. An octahedral geometry may be assigned for metal complexes on the basis of electronic absorption data and magnetic moment parameters. The compounds were evaluated for their biological activity by in vitro antimicrobial screening against bacteria Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Salmonella typhi and fungi Candida parapsilosis and Saccharomyces cerevisiae. The results indicate that metal complexes exhibit more activity than free ligands against studied microbes.  相似文献   

8.
Two new metal–organic coordination polymers {[Co(L1)(nip)]·H2O} n (1) and [Co(L2)(ip)] n (2) (H2ip = isophthalic acid, L1 = 1,3-bis(benzimidazol-1-ylmethyl)benzene, L2 = 1,4-bis(5-methylbenzimidazol-1-ylmethyl)benzene, H2nip = 5-nitroisophthalic acid) have been synthesized under hydrothermal conditions and characterized by physicochemical and spectroscopic methods as well as single-crystal X-ray diffraction analysis. The analysis reveals that complex 1 has a 1D double chain structure connected by L1 and nip2? ligands, which is further assembled into a 3D bbf (moganite network) supermolecular framework via two types of C–H···O hydrogen bond interactions. Complex 2 possesses a 3D MOF with a four-connected cds (CdSO4 network) topology. The fluorescence and catalytic properties of the complexes for the degradation of Congo red have been investigated.  相似文献   

9.
The reaction of phosphorus ylide, acetylmethylenetriparatolylphosphorane (L) with HgX2 (X = Cl, Br, I and NO3) in equimolar ratios using acetone and dimethylformamide as solvents leads to binuclear products. 31P NMR spectroscopy was used to investigate the stoichiometry and stability of a HgX2 complex with CH3COCHP(p-tolyl)3 (L) in binary acetone–dimethylformamide mixtures of varying composition. In all cases studied, the variation of 31P NMR chemical shift with the [HgX2]/[L] mole ratio indicated the formation of 1:1 complexes. The formation constants of the resulting complexes were evaluated from computer fitting of the mole ratio data to an equation that relates the observed chemical shifts to the formation constant. In all mercuric salts used, the stabilities of the resulting 1:1 complexes varied in the order Hg(NO3)2 > HgCl2 > HgBr2 > HgI2. It was found that, in the case of all complexes, an increase in the percentage of dimethylformamide in the solvent mixtures significantly decreases the stability of the complexes.  相似文献   

10.
Two coordination polymers, [Co(L1)(IPA] n (1) and {[Ag(L2)(HMIPA)]·H2O} n (2) (H2IPA = isophthalic acid, L1 = 1,2-bis(5,6-dimethylbenzimidazol-1-ylmethyl)benzene, H2MIPA = 5-methylisophthalic acid, L2 = 1,6-bis(5,6-dimethylbenzimidazol-1-yl)hexane, have been synthesized and characterized by physicochemical and spectroscopic methods, as well as single-crystal X-ray diffraction. In 1, six-coordinated cobalt centers are bridged by L1 and IPA2? ligands to generate a (4,4) two-dimensional layer. However, complex 2 features a 1D chain structure, which is further extended by O–H···O hydrogen bonding interactions into a 2D supramolecular layer with (63) topology. The fluorescence and thermal gravimetric analysis of both complexes were also explored. Furthermore, the complexes 1 and 2 exhibit remarkable catalytic properties for the degradation of methyl orange dyes in a Fenton-like process.  相似文献   

11.
Two mixed-ligand complexes, [Cu(L)(2imi)] (1) and [Ni(L)(2imi)]·MeOH (2) [L = 2-(((5-chloro-2-oxyphenyl)imino)methyl)phenolato) and 2imi = 2-methyl imidazole], have been prepared by the reaction of appropriate metal salts with H2L and 2-methyl imidazole. Their structures were characterized by microanalysis, FT-IR, UV–vis, molar conductivity, and 1H NMR for [Ni(L)(2imi)]·MeOH. The structures were determined using single crystal X-ray diffraction. Each four-coordinate metal center, Cu(II) in 1 and Ni(II) in 2, is surrounded by donors of Schiff base (L2?) and N of 2-methyl imidazole in square planar geometries. α-Amylase activities of these compounds have also been investigated. The experimental data showed that α-amylase was inhibited by Ni(II) complex while the Cu(II) complex causes a 1.3-fold decrease in Km value. Antimicrobial results show that these compounds, especially the Cu(II) complex, have potential for antibacterial activity against Gram negative and Gram positive bacteria and antifungal activity against Aspergillus fumigatus.  相似文献   

12.
Cu(II) complexes of the tridentate ligand N-(methylpyridin-2-yl)-amidino-O-methylurea (L), namely [Cu(L)Cl2] and [Cu(L)ClO4]ClO4, have been investigated for interactions with DNA by spectroscopic methods and viscosity measurements. Both complexes bind to DNA through non-intercalative interactions. [Cu(L)Cl2] (K b = 2.81 × 105 M?1) shows similar DNA-binding potential to [Cu(L)ClO4]ClO4 (K b = 1.57 × 105 M?1). Investigation of the chemical nuclease properties toward plasmid pBR322 DNA by gel electrophoresis and atomic force microscopy (AFM) suggests that both complexes are able to cleave the supercoiled form (Form I) to the nicked (Form II) and linear forms (Form III) through an oxidative pathway. The possible reactive oxygen species have been investigated by the use of scavengers, indicating that hydroxyl radicals may be involved in the DNA cleavage mechanism. Both of these complexes show similar activities against selected human cancer cell lines.  相似文献   

13.
Seven-coordinate Fe(III) complexes [Fe(dapsox)(H2O)2]+, where [dapsox = 2,6-diacetylpyridine-bis(semioxamazide)] is an equatorial pentadentate ligand with five donor atoms (2O and 3N), were studied with regard to their acid–base properties and complex formation equilibria. Stability constants of the complexes and the pK a values of the ligands were measured by potentiometric titration. The interaction of [Fe(dapsox)(H2O)2]+ with the DNA constituents, imidazole and methylamine·HCl were investigated at 25 °C and ionic strength 0.1 mol·dm?3 NaNO3. The hydrolysis constants of the [Fe(dapsox)(H2O)2]+ cation (pK a1 = 5.94 and pK a2 = 9.04), the induced ionization of the amide bond and the formation constants of the complexes formed in solution were calculated using the nonlinear least-squares program MINIQUAD-75. The stoichiometry and stability constants for the complexes formed are reported. The results show the formation of 1:1 and 1:2 complexes with DNA constituents supporting the hepta-coordination mode of Fe(III). The concentration distributions of the various complex species were evaluated as a function of pH. The thermodynamic parameters ΔH° and ΔS° calculated from the temperature dependence of the equilibrium constants were investigated for interaction of [Fe(dapsox)(H2O)2] with uridine.  相似文献   

14.
New dihydrazinium divalent transition metal trimellitate hydrates of empirical formula (N2H5)2M(Html)2·nH2O, where n = 1 for M = Co or Ni, and n = 2 for M = Mn, Zn, or Cd (H3tml = trimellitic acid), and monohydrazinium cadmium trimellitate, [(N2H5)Cd(Html)1.5·2H2O] have been prepared and characterized by physico-chemical methods. Electronic spectroscopic, and magnetic moment data suggest that Co and Ni complexes adopt an octahedral geometry. The IR spectra confirm the presence of monodentate carboxylate anion (Δν = νasy(COO?) ? νsym(COO?) > 190 cm?1) and coordinated N2H5 + ion (νN–N 1015 ? 990 cm?1) in all the complexes. All the complexes undergo endothermic decomposition eliminating CO2 in the temperature region 200–250 °C, followed by exothermic decomposition (in the range of 500–570 °C) of organic moiety to give the respective metal carbonate as the end products except nickel and cobalt complexes, which leave respective metal oxides. X-ray powder diffraction patterns reveal that Ni and Co complexes are isomorphous as are those of, Zn(II) and Cd(II) of the type, (N2H5)2M(Html)2·2H2O.  相似文献   

15.
The mixed-ligand complex formation in the system Cu2+−Edta4−−(CH2)6(NH2)2 (L), where L is hexamethylenediamine has been calorimetrically, pH-potentiometrically and spectrophotometrically studied in aqueous solution at 298.15 K and the ionic strength of I = 0.5 (KNO3). The thermodynamic parameters of formation of the CuEdtaL2−, CuEdtaHL (CuEdta)2L4− and (CuEdta)2En4− complexes have been determined. The most probable coordination mode for the complexone and the ancillary ligand in the mixed-ligand complexes was discussed.  相似文献   

16.
The reduction of the octahedral cobalt(III) complex CoIII(HL)·9H2O, H4L = 1,8-bis(2-hydroxybenzamido)-3,6-diazaoctane by glutathione (GSH) has been studied by conventional spectrophotometry at 25.0 ≤ t/°C ≤ 45.0, 0.02 ≤ [H+]/mol dm?3 ≤ 0.20 and I = 0.3 mol dm?3 (NaClO4). The reaction is biphasic. The fast initial phase is attributed to the H+-induced formation of the mixed ligand complex, [CoIII(H2L)GSH]+, for which the rate-limiting step is the chelate ring opening via CoIII–NH (amide–N) bond cleavage of the protonated species, [CoIII(H2L)]+. Outer-sphere association equilibria between GSH/GSH2 + and [CoIII(H2L)]+ substantially retard the ring opening process and consequently the mixed ligand complex formation. This is then followed by a slow phase involving reduction of [CoIII(H2L)GSH]+ by both GSH and GSH2 +. The final products are the corresponding Co(II) complex and the oxidized form of GSH, GS–SG. The kinetic data and activation parameters for the redox process are interpreted in terms of an outer-sphere electron transfer mechanism.  相似文献   

17.
Four azido-bridged dinuclear Mn(II) complexes, [Mn2(phen)4 μ-1,1-N3)2][FeIII(bpmb)(CN)2]2·H2O (1), [Mn2(phen)4(μ-1,1-N3)2][FeIII(bpClb)(CN)2]2·H2O (2), and [Mn2(phen)4(μ-1,1-N3)2][MIII(bpdmb)(CN)2]2·3H2O [M = Fe (3) or Cr (4); phen = 1,10-phenanthroline, bpmb2– = 1,2-bis(pyridine-2-carboxamido)-4-methyl-benzenate, bpClb2– = 1,2-bis(pyridine-2-carboxamido) 4-chloro-benzenate, bpdmb2– = 1,2-bis(pyridine-2-carboxamido)-4,5-dimethyl-benzenate], have been synthesized using the synthetic strategy of large anion inducement. Single-crystal X-ray diffraction analysis reveals that all four complexes are doubly end-on (EO) azido-bridged binuclear Mn(II) complexes with two large [M(L)(CN)2] (L = bpmb2?, bpClb2?, or bpdmb2?) building blocks acting as charge-compensating anions. The magnetic properties of the complexes have been investigated, and the results indicate that the magnetic coupling between two Mn(II) centers through the EO azide bridges is ferromagnetic, with J = 0.64(1) cm?1 for 1, 0.43(1) cm?1 for 2, 0.50(1) cm?1 for 3, and 0.66(2) cm?1 for 4. The magneto-structural relationships of EO azido-bridged Mn(II) systems are discussed.  相似文献   

18.
New copper (II) complexes of Schiff bases with 1,2-di(imino-2-aminomethylpyridil)ethane with the general composition CuLX m (H2O) x , [L = Schiff base, X = Cl?, Br?, NO3 ?, ClO4 ?, CH3COO?, m = 2; X = SO4 2?, m = 1] were prepared by template synthesis. The complexes were characterized by elemental analysis, conductivity measurements, magnetic moments, IR, UV–VIS and EPR spectra. The thermal behavior of complexes was studied using thermogravimetry (TG), differential thermal analysis (DTA) and differential scanning calorimetry (DSC). Infrared spectra of all complexes are in good agreement with the coordination of a neutral tetradentate N4 ligand to the cooper (II) through azomethinic and pyridinic nitrogen. Magnetic, EPR and electronic spectral studies show a monomeric distorted octahedral geometry for all Cu(II) complexes. Conductance measurements suggest the non-electrolytic nature of the compounds, except for copper (II) nitrate and perchlorate complexes which are 1:2 electrolytes. Heats of decomposition, ΔH, associated with the exothermal effects were also determined.  相似文献   

19.
Two cobalt(II) coordination polymers, [Co(L1)(tbi)(H2O)] n (1) and [Co(L2)(tbi)] n (2) (L1 = 1,4-bis(benzimidazole)butane, L2 = 1,4-bis(2-methylbenzimidazole)butane, H2tbi = 5-tert-butyl isophthalic acid) have been synthesized under hydrothermal conditions and characterized by physicochemical and spectroscopic methods as well as by single-crystal X-ray diffraction analysis. Both complexes exhibit similar 2D (4,4) layer structures, constructed from tbi2? and bis(benzimidazole)-based bridging ligands. The cobalt centers display different coordination environments, with an octahedral geometry in 1 and a distorted square-pyramidal configuration in 2. The thermal stabilities, fluorescence and catalytic properties of both complexes have been investigated.  相似文献   

20.
New seven metal complexes of tioconazole drug with the general formulae [MCl2(L)2(H2O)x].yH2O (where, x = 0 and y = 1 for M = Mn(II) or x = 2, y = 2 for M = Co(II)), and x = 0, y = 3 for M = Cu(II), Ni(II), Zn(II)) and [MCl2(L)2(H2O)2]Cl.3H2O (where M = Cr(III) and Fe(III)) have been prepared and characterized based on elemental analyses, IR, magnetic moment, molar conductance, and thermal analyses techniques. From molar conductance data bivalent metal chelates are non-electrolytes while Cr(III) and Fe(III) chelates are electrolytes and of 1:1 type. According to the IR spectral data, TCNZ is coordinated to the metal ions in a neutral unidentate manner with N donor site of the imidazole–N. All the complexes are octahedral except Mn(II) complex has tetrahedral structure. TCNZ drug and its metal complexes were also screened for their biological activity.  相似文献   

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