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1.
A series of binuclear Co(II), Ni(II) and Cu(II) complexes were synthesized by the template condensation of glyoxal, biacetyl or benzil bis-hydrazide, 2,6-diformyl-4-methylphenol and Co(II), Ni(II) or Cu(II) chloride in a 2:2:2 M ratio in ethanol. These 22-membered macrocyclic complexes were characterized by elemental analyses, magnetic, molar conductance, spectral, thermal and fluorescence studies. Elemental analyses suggest the complexes have a 2:1 stoichiometry of the type [M2LX2nH2O and [Ni2LX22H2O]·nH2O (where M = Co(II) and Cu(II); L = H2L1, H2L2 and H2L3; X = Cl; n = 2). From the spectroscopic and magnetic studies, it has been concluded that the Co(II) and Cu(II) complexes display a five coordinated square pyramidal geometry and the Ni(II) complexes have a six coordinated octahedral geometry. The Schiff bases and their metal complexes have also been screened for their antibacterial and antifungal activities by the MIC method.  相似文献   

2.
The synthesis and physico-chemical characterization of Fe(II) and Mn(II) complexes of 2-[4,6-di(tert-butyl)-2,3-dihydroxyphenylsulfanyl]acetic acid (HLI) and 2-[4,6-di(tert-butyl)-2,3-dihydroxyphenylsulfinyl]acetic acid (HLII) were carried out. The investigation of the molecular and electronic structure of Cu(II), Ni(II), Zn(II), Fe(II) and Mn(II) complexes has been performed within the density functional theory (DFT) framework. The computed properties were compared to the experimental ones, and molecular structures of the compounds were proposed based on the array of spectral data and quantum chemical calculations. Antibacterial activity of the Fe(II) and Mn(II) complexes was evaluated in comparison with Cu(II), Co(II), Ni(II) and Zn(II) complexes and three standard antibiotics; it was found to follow the order: (1) Сu(LI)2 > Mn(LI)2 > HLI > Ni(LI)2 > Zn(LI)2 > Fe(LI)2 > Co(H2O)2LI; (2) Cu(LII)2 > Сo(LII)2 > Ni(LII)2 > Mn(H2O)2(LII)2 > Fe(LII)2 > HLII > Zn(LII)2; their reducing ability (determined electrochemically) followed the same order. Spectrophotometric investigation was carried out in order to estimate the rate of the reduction of bovine heart сytochrome c with the ligands and their metal(II) complexes. The complexes Сu(LI)2, Mn(LI)2 and Co(LII)2 with the high reducing ability were found to be characterized by the highest rates of Cyt с reduction. NADPH:cytochrome P450-reductase had no substantial effect on the rate of сytochrome c reduction with HLI and HLII ligands.  相似文献   

3.
Two new isomorphous tetranuclear complexes [Cu4L2(4,4′-bipy)2]·(ClO4)4·2CH3CN·2H2O (1) and [Zn4L2(4,4′-bipy)2]·(ClO4)3·CH3O·4H2O (2) have been obtained and fully characterized (where bipy = bipyridine, H2L = macrocycle is the [2+2] condensation product of 2,6-diformyl-4-fluoro-phenol and 1,4-diaminobutane). They exhibit wheel-like configuration in which two 4,4′-bipy molecules connect two dinuclear [M2L]2+ units. The interactions of the complexes with calf thymus DNA were studied by UV-Vis and CD spectroscopic techniques. The binding constants of 1 and 2 are 2.27 × 106 and 3.89 × 105 M−1, respectively. The magnetic measurement of 1 reveals that there are strong antiferromagnetic coupling (J = -272.6 cm−1) between two Cu(II) ions in the macrocyclic unit and ferromagnetic interaction (j′ = 41.7) between the Cu(II) ions in two adjacent macrocyclic units. Furthermore, the cyclic voltammogram of 1 shows that it undergoes two quasi-reversible processes with the half wave potentials -0.232 and -0.606 V, respectively.  相似文献   

4.
The DNA cleavage activities of nickel(II) ion and four closely related macrocyclic nickel(II) complexes NiL1 ∼ NiL4 in the absence of any added redox cofactors are compared and the structure of NiL3 methanol solvate has been characterized by single crystal X-ray analysis, where L1 ∼ L4 are the dianions of tetraazamacrocyclic oxamido Schiff bases. In NiL3·MeOH, the macrocyclic [N4] ligand coordinates to the central Ni(II) ion forming a distorted square–planar geometry. The adjacent mononuclear molecules are linked by O–H?O hydrogen bonds and Ni?O and Ni?L van der Waals forces into 2D supramolecular structure. Agarose gel electrophoresis studies indicate that the ability of these nickel(II) complexes to cleave DNA is highly dependent upon the ligand employed. In the absence of any added oxidizing agents, only NiL3 is a relatively good DNA cleavage agent, and the process of plasmid DNA cleavage is much sensitive to ionic strength and pH value. The NiL3-mediated DNA cleavage reaction is a typical pseudo-first-order consecutive reaction, and the rate constants of 0.148 ± 0.007 h−1 (k1) and 0.0118 ± 0.0018 h−1 (k2) for the conversion of supercoiled to nicked DNA and nicked to linear DNA are obtained in presence of 0.5 mmol L−1 NiL3. The results of DNA cleavage experiments, combining with those of circular dichroism (CD) and fluorescence spectroscopy indicate that the main binding modes between DNA and the complexes should be groove binding and electrostatic interaction.  相似文献   

5.
A new category of dinucleating macrocyclic Schiff base ligands with ring sizes from 34- to 52-membered have been synthesised employing metal template procedures involving the reaction of o-phenylenediamine with a series of α,ω-bis(3′-hydroxy-4′-formylphenyloxy)alkanes in the presence of calcium(II), barium(II) or manganese(II). The latter cations act as ‘transient’ templates for formation of the corresponding metal-free Schiff base macrocyclic ligands, H4Ln (where n signifies the number of carbons in each linking bis-alkoxy chain); the macrocycles corresponding to n = 4, 6 and 8 were isolated and characterised while, for n = 1, in which single methylene groups acts as the bridges between salicyl moieties, the cyclic product was used directly for preparation of its dinuclear complex, [Zn2L1], without prior isolation. Evidence for the templating role of barium in the preparation of H4L6 and H4L8 was obtained by isolation of the corresponding species of type H4Ln·2Ba(ClO4)2 (n = 6 or 8) as ‘intermediates’ before generation of the respective metal-free macrocycles. Reaction of zinc(II) acetate with the free macrocycles in methanol yielded complexes of type [Zn2Ln] in all cases. A related non-cyclic ligand, H2L0 and its corresponding mononuclear complex, [ZnL0]·H2O, were also synthesised and its spectral properties compared with those of the macrocyclic derivatives. The elemental analyses, 1H NMR, IR, UV–Vis and MS spectra of the respective zinc complexes in each case were in accord with the formation of the expected 2:2 condensation product. The results of DFT calculations to probe aspects of the electronic and structural natures of both H2L1 and H4L4 are briefly presented.  相似文献   

6.
Two new heteropolynuclear Schiff base complexes, [Ni2Cd2L2Cl2(μ-Cl)2] (1) and [Ni2CdL′2Cl(H2O)]ClO4·H2O (2) where L = [N,N′-bis(2-hydroxyacetophenylidene)]propane-1,2-diamine and L′ = [N,N′-bis(2-hydroxypropiophenylidene)]propane-1,2-diamine, have been synthesized by refluxing equimolar amounts of nickel perchlorate, cadmium chloride and the respective tetradentate Schiff base ligand, H2L or H2L′ in methanol medium. The complexes have been characterized by microanalytical, spectroscopic, single crystal X-ray diffraction and other physicochemical studies. Structural studies on 1 reveal the presence of a bis(heterodinuclear) [NiIICdII]2 unit in which the two central cadmium ions are doubly chloro-bridged with each other and each of them is connected to a nickel(II) center through two phenolate oxygen bridges. In contrast, complex 2 contains a heterotrinuclear [NiIICdIINiII] unit in which the central cadmium ion is connected to two nickel(II) centers through two doubly bridging phenolate oxygen atoms. The Cd(II) ions in 1 and 2 adopt distorted, square pyramidal (CdO2Cl3) and octahedral (CdO5Cl) geometries respectively. On the other hand, the Ni(II) ions in both 1 and 2 assume the same coordination geometry, i.e. a distorted square planar (NiO2N2) arrangement. Intermolecular C-H?Cl or O-H?Cl and O-H?O hydrogen bonding interactions are operative in the complexes to build up 2D supramolecular structures in their solid states.  相似文献   

7.
The new nickel selenite chloride, Ni5(SeO3)4Cl2, was obtained by high-temperature solid state reaction of NiCl2, Ni2O3 and SeO2 in a 1:2:4 molar ratio at 700 °C in an evacuated quartz tube. Its structure was established by single-crystal X-ray diffraction. Ni5(SeO3)4Cl2 crystallizes in the triclinic system, space group P-1 (No. 2) with cell parameters of a=8.076(2), b=9.288(2), c=9.376(2) Å, α=101.97(3), β=105.60(3), γ=91.83(3)° and Z=2. All nickel(II) ions in Ni5(SeO3)4Cl2 are octahedrally coordinated by selenite oxygens or/and chloride anions (([Ni(1)O5Cl], [Ni(2)O4Cl2], [Ni(3)O5Cl], [Ni(4)O6] and [Ni(5)O4Cl]). The structure of the title compound features a condensed three-dimensional (3D) network built by Ni(II) ions interconnected by SeO32− anions as well as Cl anions. Magnetic property measurements show strong antiferromagnetic interaction between nickel(II) ions.  相似文献   

8.
Eight new heterodinuclear Cu(II)–M(II) (M = Pb and Zn) complexes of four new phenol based compartmental macrocyclic ligands, possessing contiguous (N2O2) and (NxO2) (x = 2, 3) coordination sites, were prepared by the template reaction of [N,N′-bis(3-formyl-5-methylsalicylidene)ethane-1,2-diaminato]copper(II), with various di- and/or tri-amines in the presence of Pb(II) and Zn(II) ions. The crystal structure of [CuZnL3(H2O)](ClO4)2, 6, was determined by X-ray diffraction and shows that the Zn(II) and Cu(II) ions reside in the N2O2 sites of the macrocyclic ligand. The fifth coordination site of the Zn centre is occupied by a water ligand. All the complexes have been characterized by elemental analysis, molar conductivity and spectroscopic methods (IR and UV). Also, all the synthesized complexes were screened for their antibacterial and antifungal activity against Escherichia coli, Staphyloccocus aureus and Candida albicans.  相似文献   

9.
Three new binuclear Ni(II) complexes [{Ni(L22py)Cl}2](ClO4)2 (1), [{Ni(L23py)Cl}2](ClO4)2 (2), and [{Ni(L33py)Cl}2](ClO4)2 (3), {L22py = N-(2-pyridylmethyl)-N-(2-aminoethyl)-1,2-diaminoethane, L23py = N-(2-pyridylmethyl)-N-(2-aminoethyl)-1,3-diaminopropane, L33py = N-(2-pyridylmethyl)-N-(3-aminopropyl)-1,3-diaminopropane} have been synthesized. Single crystal X-ray structure analysis showed that in each complex two distorted octahedral Ni(II) ions are bridged asymmetrically by a pair of chloride anions. Variable temperature magnetic susceptibility measurements of 1 and 3 revealed dominant ferromagnetic exchange interactions.  相似文献   

10.
Four novel molecular square grids were achieved by self-assembly using the flexible ligands bis(di-2-pyridyl ketone) thiocarbohydrazone (H2L1), bis(quinoline-2-carbaldehyde) thiocarbohydrazone (H2L2), bis(di-2-pyridyl ketone) carbohydrazone (H2L3) and bis(2-benzoylpyridine) carbohydrazone (H2L4). Three complexes were given a general formula of [Ni(HL)]4[PF6]4 · nH2O and one [Ni2(HL2)L2]2(PF6)2 · 7H2O. The MALDI-MS spectra reveal the formation of tetranuclear molecular squares. The square grid of the Ni(II) centers in all the complexes were organized by deprotonated ligands. The complex [Ni(HL1)]4[PF6]4 · 11H2O crystallized as [Ni(HL1)]4(PF6)4 · 0.5 CH3CH2OH · 2.8H2O and X-ray study revealed octahedral geometries around the Ni(II) centers. Variable temperature magnetic studies suggest intramolecular antiferromagnetic coupling between the Ni(II) electrons by a super exchange mechanism through intervening sulfur/oxygen atoms.  相似文献   

11.
The crystallographic structure of DyNiO3 has been investigated at T=200, 100, and 2 K from high-resolution neutron powder diffraction (NPD) data. We show that the structure is monoclinic, space group P21/n, from the metal-insulator transition temperature at TMI=564 K down to 2 K. The Ni atoms occupy two different sites 2d (Ni1) and 2c (Ni2), whose valences, estimated from bond-valence consideration, are +2.43(1) and +3.44(1) at 2 K, respectively. This is interpreted as the result of a partial charge disproportionation of the type 2Ni3+→Ni1(3−δ)++Ni2(3+δ)+, with δ≈0.55 at T=2 K. The magnetic structure has been studied from a NPD pattern at T=2 K, well below the establishment of the antiferromagnetic (AFM) ordering at TN=154 K, as well as from sequential data collected from 16 K down to 2 K. The magnetic order is defined by the propagation vector k=(1/2,0,1/2). Two possible magnetic structures are compatible with the magnetic intensities. In the second solution both Ni sublattices participate in the magnetic order, as well as Dy since it corresponds to a total disproportionation of Ni3+ to Ni2+ and Ni4+. In the second solution both Ni sublattices participate in the magnetic order, as well as Dy. The magnetic moments for Ni1 and Ni2 atoms at T=2 K are 1.8 (2) and 0.8 (2) μB, respectively. These values are also compatible with a partial charge disproportionation. Dy3+ ions exhibit long-range magnetic ordering below 8 K. An abrupt contraction of the unit-cell volume is observed at this temperature, due to a magnetoelastic coupling. The magnetic moment for Dy3+ at T=2 K is 7.87 (6) μB.  相似文献   

12.
Treatment of [M(H2Li)] with UCl4 in pyridine led to the formation of the dinuclear complexes [MLi(py)UCl2(py)2] and/or [Hpy][MLi(py)UCl3] [Li = N,N′-bis(3-hydroxysalicylidene)-R, R = 1,2-phenylenediamine (i = 1), R = trans-1,2-cyclohexanediamine (i = 2), R = 2-amino-benzylamine (i = 3), R = 1,3-propanediamine (i = 4), R = 2,2-dimethyl-1,3-propanediamine (i = 5); M = Cu or Ni]. The crystal structures show that the 3d and 5f ions occupy, respectively, the N2O2 and O4 cavities of the Schiff base ligand, the U4+ ion adopting a dodecahedral or pentagonal bipyramidal configuration in the neutral and anionic complexes, respectively.  相似文献   

13.
N-(2-Hydroxybenzyl)aminopyridines (Li) react with Cu(II) and Pd(II) ions to form complexes in the compositions Cu(Li)2(CH3COO)2 · nH2O (n = 0, 2, 4), Pd(Li)2Cl2 · nC2H5OH (n = 0, 2) and Pd(L2)2Cl2 · 2H2O. In the complexes, the ligands are neutral and monodentate which coordinate through pyridinic nitrogen. Crystal data of the complexes obtained from 2-amino pyridine derivative have pointed such a coordinating route and comparison of the spectral data suggests the validity of similar complexation modes of other analog ligands. Cu(II) complex of N-(2-hydroxybenzyl)-2-aminopyridine (L1), [Cu(L1)2(CH3COO)2] has slightly distorted square planar cis-mononuclear structure which is built by two oxygen atoms of two monodentate carboxylic groups disposed in cis-position and two nitrogen atoms of two pyridine rings. The remaining two oxygen atoms of two carboxylic groups form two Cu and H bridges containing cycles which joint at same four coordinated copper(II) ion. IR and electronic spectral data and the magnetic moments as well as the thermogravimetric analyses also specify on mononuclear octahedric structure of complexes [Cu(L2)2(CH3COO)2 · 2H2O] and [Cu(L3)2(CH3COO)2 · 4H2O] where L2 and L3 are N-(2-hydroxybenzyl)-2- or 3-aminopyridines, respectively.  相似文献   

14.
3,4,5,6-Tetrafluoro-2-nitrophenoxide (L) forms complexes with rare earth M3+ ions. X-ray crystal structures of substances with the stoichiometry Cs2ML5 · mEt2O (M = Er, m = 0; M = Er, m = 1; M = Y, m = 1.5; M = Yb, m = 1) have been determined. Each M3+ ion is coordinated to two bidentate and three monodentate L ions; Et2O does not coordinate to M3+. The complexes absorb both visible and ultraviolet light. The solid Er3+ and Yb3+ complexes have unusually long lifetimes (τ = 20.2 μs and 142 μs, respectively) for the decay of their luminescence in the near-infrared region following photoexcitation; this is attributed to the lack of C–H bonds and other high frequency oscillators that could cause vibrational quenching.  相似文献   

15.
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 P1 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.  相似文献   

16.
The solvent-free conditions were employed to synthesise symmetrical Schiff base ligand from 2,6-diaminopyridine with cinnamaldehyde in (1 min) with a fair yield utilizing formic acid as a catalyst. Through coordination chemistry, new heteroleptic complexes of Cu(II), Co(II), Ni(II), Pt(II), Pd(II) and Zn(II) were achieved from Schiff base as a primary chelator (L1) and 2,2′‐bipyridine (2,2′-bipy) as a secondary chelator (L2). The prepared compounds have been characterized by elemental analysis, molar conductivity, magnetic susceptibility, FTIR, 1H NMR, UV–visible, mass spectrometry, and thermal gravimetric analysis, and screened in vitro for their potential as antibacterial activity by the agar well diffusion method. The metal complexes were formulated as [M (L1) (L2) (X)] YnH2O, L1 = Schiff base, L2 = 2,2′-bipy, (M = Cu(II), Co(II), Zn(II), Y = 2NO3, n = 1), (M = Ni(II), X = 2H2O, Y = 2NO3, n = 0) and (M = Pd(II) Pt(II), Y = 2Cl, n = 0). Both L1 and L2 act as a neutral bidentate ligand and coordinates via nitrogen atoms of imine and 2,2′-bipy to metal ions. The metal complexes were found to be electrolytic, with square-planar heteroleptic Cu(II), Co(II), Pt(II), and Pd(II) chelates and octahedral Ni(II) complex. As well as tetrahedral geometry, has been proposed for the complex of Zn(II). Furthermore, the biological activity study revealed that some metal chelates have excellent activity than Schiff base when tested against Gram-negative and Gram-positive strains of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Finally, it was found that the Zn(II) and Pd(II) complexes were more effective against both types of bacteria tested than the imine and other metal complexes.  相似文献   

17.
Four new complexes [Ni3(μ-L)6(H2O)6](NO3)6·6H2O (1), [Co3(μ-L)6(H2O)6](NO3)6·6H2O (2), [Ni3(μ-L)6(H2O)4(CH3OH)2](NO3)6·4H2O (3), [Co3(μ-L)6(H2O)4(CH3OH)2](NO3)6·4H2O (4) (L = 4-amino-3,5-dimethanyl-1,2,4-triazole) were synthesized and structurally characterized by X-ray single-crystal diffraction. The structural analyses show that complex 1 and 2 are isomorphous; complex 3 and 4 are isomorphous. Four complexes all consist of the linear trinuclear cations ([M3(μ-L)6(H2O)6]6+ (M = Ni,Co) for 1 and 2; [M3(μ-L)6(H2O)4(CH3OH)2]6+ (M = Ni,Co) for 3 and 4), NO3 anions and crystallized water molecules. In the trinuclear cations, the central M(II) ions and two terminal M(II) ions are bridged by three triazole ligands. Other eleven solid solution compounds which are isomorphous with complex 3 and 4 were obtained by using different ratio of Ni(II) and Co(II) ions as reactants and ICP result indicates that ligand L has higher selectivity of Ni(II) ions than that of Co(II) ions. The magnetic analysis was carried out by using the isotropic spin Hamiltonian ? = −2J(?1?2 + ?2?3) (for complexes 1 and 3) and simultaneously considering the temperature dependent g factor (for complexes 2 and 4). Both the UV-Vis spectra and the magnetic properties of the solid solutions can be altered systematically by adjusting the Co(II)/Ni(II) ratio.  相似文献   

18.
An artificial neural network (ANN) procedure was used in the development of a catalytic spectrophotometric method for the determination of Cu(II) and Ni(II) employing a stopped-flow injection system. The method is based on the catalytic action of these ions on the reduction of resazurin by sulfide. ANNs trained by back-propagation of errors allowed us to model the systems in a concentration range of 0.5-6 and 1-15 mg l−1 for Cu(II) and Ni(II), respectively, with a low relative error of prediction (REP) for each cation: REPCu(II) = 0.85% and REPNi(II) = 0.79%. The standard deviations of the repeatability (sr) and of the within-laboratory reproducibility (sw) were measured using standard solutions of Cu(II) and Ni(II) equal to 2.75 and 3.5 mg l−1, respectively: sr[Cu(II)] = 0.039 mg l−1, sr[Ni(II)] = 0.044 mg l−1, sw[Ni(II)] = 0.045 mg l−1 and sw[Ni(II)] = 0.050 mg l−1. The ANNs-kinetic method has been applied to the determination of Cu(II) and Ni(II) in electroplating solutions and provided satisfactory results as compared with flame atomic absorption spectrophotometry method. The effect of resazurin, NaOH and Na2S concentrations and the reaction temperature on the analytical sensitivity is discussed.  相似文献   

19.
A series of mononuclear complexes based on lanthanide ions has been synthesized and X-ray characterized. The compounds [LnIIIL2(NO3)3(H2O)2] (Ln = La, Ce, Pr, Nd, Sm, Gd and Tm; L = 2,6-bis(2-formylphenoxymethyl)pyridine) are found to be isomorphous and isostructural. Ligand L systematically coordinates through one carbonyl functionality, and the resulting complexes are placed on a twofold axis in crystals belonging to C2/c space-group. Emission spectra for Ln = La, Pr, Nd revealed a correlation between the Ln–O coordination bond length and the photoluminescent properties of the complexes, in line with a Förster–Dexter mechanism for intramolecular energy transfer. Ligand L is therefore a suitable sensitizer for lanthanide ions.  相似文献   

20.
Reaction of the dimeric allyl-nickel(II) chloro complex [Ni(η3-C3H5)(μ-Cl)]2 (5) with sulfur donor ligands (L = L10-L13) in the presence of ( = 3,5-(CF3)2C6H3) gives the corresponding cationic mononuclear complexes of the type [Ni(η3-C3H5)(L)2]+ (1-4) [L = L10 = diphenyl sulfide (1); L = L11 = 4,4′-thiodiphenol (2); L = L12 = 4,4′-thio-bis(6-tert-butyl-o-cresol) (3); L = L13 = 4,4′-thio-bis (6-tert-butyl-m-cresol) (4)]. All of these complexes were characterized by elemental analysis and NMR spectroscopy, as well as the representative complex 3 additionally by single-crystal X-ray analysis. In comparison to the known complex [Ni(η3-C3H5)(η6-BHT)][B] (BHT = 3,5-di-tert-butyl-4-hydroxytoluene), the herein described cationic complexes show an increased stability towards water. The activity of the complexes for butadiene polymerization in aqueous emulsions was studied.  相似文献   

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