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1.
Abstract The synthesis of the flexible ligand 2,6-bis-{(bis-(2-aminoethyl)amino(methyl}anisole (L) is reported. The basicity behaviour in aqueous solution was studied by potentiometry (25°C, I = 0.15 mol dm ?3, Me 4NCl). L behaves as pentaprotic base (logK 1 = 10.31(2), logK 2 = 9.65(2), logK 3 = 9.16(2), logK 4 = 8.39(2), logK 5 = 2.14(2)). The stability constants for Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes were determined by potentiometry and all of these metalions were found to form both mono and binuclear species: logK ML = 9.39(3) for Co(II); 14.5(1) for Ni(II); 17.57(7) for Cu(II); 10.62(2) for Zn(II) and 9.83(3) for Cd(II). LogK M2L = 15.19(3) for Co(II); 19.57(5) for Ni(II); 28.44(3) for Cu(II); 16.77(6) for Zn(II) and 14.62(3) for Cd(II). The crystals of [Cu 4L 2(N 3) 6](ClO 4) 2·H 2O are triclinic, space group P-1 a = 13.770(6), b = 14.043(2), c = 16.800(3) Å, α = 105.700(1), β = 102.790(3), γ = 103.660(3)°, Z = 2. L behaves as ditopic ligand and the crystal lattice consists of branched chains of Cu(II) ions. 相似文献
2.
The stoichiometry and stability constant of metal complexes with 4-(3-methoxy-salicylideneamino)-5-hydroxynaphthalene-2,7-disulfonic
acid monosodium salt (H 2L) and 4-(3-methoxysalicylideneamino)-5-hydroxy-6-(2,5-dichlorophenylazo)-2,7-naphthalene disulfonic acid monosodium salt
(H 2L 1) were studied by potentiometric titration. The stability constants of H 2L and H 2L 1 Schiff bases have been investigated by potentiometric titration and u.v.–vis spectroscopy in aqueous media. The dissociation
constants of the ligand and the stability constants of the metal complexes were calculated pH-metrically at 25 °C and 0.1 m KCl ionic strength. The dissociation constants for H 2L were obtained as 3.007, 7.620 and 9.564 and for H 2L 1, 4.000, 6.525, 9.473 and 10.423, respectively. The complexes were found to have the formulae [M(L) 2] for M = Co(II), Ni(II), Zn(II) and Cu(II). The stability of the complexes follows the sequence: Zn(II) < Co(II) < Cu(II)
< Ni(II). The high stability of H 2L 1 towards Cu(II) and Ni(II) over the other ions is remarkable, in particular over Cu(II), and may be of technological interest.
Concentration distribution diagram of various species formed in solution was evaluated for ligands and complexes. The formation
of the hydrogen bonds may cause this increased stability of ligands. The pH-metric data were used to find the stoichiometry,
deprotonation and stability constants via the SUPERQUAD computer program. 相似文献
3.
Three isoxazole Schiff bases 2-((E)-(3,5-dimethylisoxazol-4-ylimino)methyl)-6-methoxyphenol (L 1), 2-((E)-(3,5-dimethylisoxazol-4-ylimino)methyl)-4,6-diiodophenol (L 2), 2-((E)-(3,5-dimethylisoxazol-4-ylimino)methyl)-6-bromo-4-chlorophenol (L 3), and their Cu(II) complexes [Cu(L 1) 2] ( 1), [Cu(L 2) 2] ( 2) and [Cu(L 3) 2] ( 3) were synthesized. All the complexes have been characterized by elemental analysis, FT-IR, ESI mass, UV-Visible, ESR, TGA, magnetic moments, and single-crystal X-ray diffraction analysis. Based on analytical data, a square planar geometry is assigned to the Cu(II) complexes with N 2O 2 donors from the Schiff base ligands. The single-crystal X-ray diffraction measurements of 1 and 2 confirmed the square planar geometry. DNA binding studies from electronic absorption titrations, viscosity measurements, and fluorescence quenching studies indicated an intercalation mode of binding of Cu(II) complexes with CT-DNA. DNA cleavage experiments of Cu(II) complexes with supercoiled plasmid pBR322 DNA have also been investigated by agarose gel electrophoresis in the presence of H 2O 2 (oxidative cleavage) and UV light (photolytic cleavage). The synthesized compounds were screened for antibacterial ( Escherichia coli, Pseudomonas putida, Klebsiella pneumoniae, Bacillus subtillis and Staphylococcus aureus) and antifungal ( Candida albicans and Aspergillus niger) activities by the paper disk method. The Cu(II) complexes showed better activity than corresponding Schiff bases. 相似文献
4.
Four new substituted amino acid ligands, N-(3-hydroxybenzyl)-glycine acid (HL 1), N-(3-hydroxybenzyl)-alanine acid (HL 2), N-(3-hydroxybenzyl)-phenylalanine acid (HL 3), and N-(3-hydroxybenzyl)-leucine acid (HL 4), were synthesized and characterized on the basis of 1H NMR, IR, ESI-MS, and elemental analyses. The crystal structures of their copper(II) complexes [Cu(L 1) 2]·2H 2O ( 1), [Cu(L 2) 2(H 2O)] ( 2), [Cu(L 3) 2(CH 3OH)] ( 3), and [Cu(L 4) 2(H 2O)]·H 2O ( 4) were determined by X-ray diffraction analysis. The ligands coordinate with copper(II) through secondary amine and carboxylate in all complexes. In 2, 3, and 4, additional water or methanol coordinates, completing a distorted tetragonal pyramidal coordination geometry around copper. Fluorescence titration spectra, electronic absorption titration spectra, and EB displacement indicate that all the complexes bind to CT-DNA. Intrinsic binding constants of the copper(II) complexes with CT-DNA are 1.32?×?10 6?M ?1, 4.32?×?10 5?M ?1, 5.00?×?10 5?M ?1, and 5.70?×?10 4?M ?1 for 1, 2, 3, and 4, respectively. Antioxidant activities of the compounds have been investigated by spectrophotometric measurements. The results show that the Cu(II) complexes have similar superoxide dismutase activity to that of native Cu, Zn-SOD. 相似文献
5.
Abstract The dissociation constant of 4–(8-quinolylazo)- l -aminonaphtalene (QAN) and conditional formation constants of its complexes with Cu(II), Ni(II) and Hg(II) were measured spectrophotometrically. The use of QAN as metallochromic indicator in copper, nickel and mercury titrations with EDTA was studied. QAN improves PAN and XO results in Cu(II) and Hg(II) titrations and is comparable to Murexide in Ni(II) titration. 相似文献
6.
New Mannich bases bis(thiosemicarbazide methyl) phosphinic acid H 3L 1 and bis(1-phenylsemicarbazide methyl) phosphinic acid H 3L 2 were synthesized from condensation of phosphinic acid and formaldehyde with thiosemicarbazide and 1-phenylsemicarbazide, respectively. Monomeric complexes of these ligands, of general formula K 2[Cr III(L n )Cl 2], K 3[Fe II(L 1)Cl 2], K 3[Mn II(L 2)Cl 2], and K[M(L n )] (M = Co(II), Ni(II), Cu(II), Zn(II) or Cd(II); n = 1, 2) are reported. The mode of bonding and overall geometry of the complexes were determined through IR, UV-Vis, NMR, and mass spectral studies, magnetic moment measurements, elemental analysis, metal content, and conductance. These studies revealed octahedral geometries for the Cr(III), Mn(II), and Fe(II) complexes, square planar for Co(II), Ni(II), and Cu(II) complexes and tetrahedral for the Zn(II) and Cd(II) complexes. Complex formation via molar ratio in DMF solution has been investigated and results were consistent to those found in the solid complexes with a ratio of (M : L) as (1 : 1). 相似文献
7.
Three new mononuclear Cu(II) and Co(III) complexes [Cu( L)Cl]ClO 4 ( 1), [Cu( L)Cl(SCN)] ( 2), and [Co( L)(N 3) 3] ( 3), where L is a reduced Schiff-base ligand bi(2-fluorobenzylaminoethyl)amine, were synthesized and characterized. X-ray crystallographical
analysis reveals that the Cu(II) atom adopts a square-planar environment in complex 1, while the geometry in 2 can be described as distorted square-pyramidal. The Co(III) atom in 3 is in a distorted octahedral geometry. Three complexes were investigated for their inhibitory activities in vitro against
jack bean urease. The Cu(II) complexes 1 and 2 were found to have excellent inhibitory activities. The Co(III) complex 3 was also shown to have activity comparable to that of acetohydroxamic acid. 相似文献
8.
Abstract The coordination of the anticancer drug mithramycin to Tb(III), Fe(III) and Cu(II) was studied in aqueous solution using absorption measurements. The stability constants were calculated from equilibrium competition experiments by means of the SQUAD program. For both first ions, the competitor was oxalic acid and for the latter the competitor was the Cu(II) ions. Cu(II) at pH 7.5, Fe(III) at pH 3.5 and Tb(III) at pH 5.5 formed respectively 1:2, 1:3 and 1:4 metal-to-ligand species. 相似文献
9.
The new Mannich bases bis(1,4-diphenylthiosemicarbazide methyl) phosphinic acid H 3L 1 and bis(1,4-diphenylsemicarbazide methyl) phosphinic acid H 3L 2 were synthesised from the condensation of phosphinic acid, formaldehyde with 1,4-diphenyl thiosemicarbazide and 1,4-diphenylsemicarbazide,
respectively. Monomeric complexes of these ligands, of general formulae K 2[Cr III(L
n
)Cl 2], K 3[Mn II(L
n
)Cl 2] and K[M(L
n
)] (M = Co(II), Ni(II), Cu(II), Zn(II) or Hg(II); n = 1, 2), are reported. The mode of bonding and overall geometry of the complexes were determined through physico-chemical
and spectroscopic methods. These studies revealed octahedral geometries for the Cr(III), Mn(II) complexes, square planar for
Co(II), Ni(II) and Cu(II) complexes and tetrahedral for the Zn(II) and Hg(II) complexes. 相似文献
10.
The potentially tridentate N,N′,O-donor N-trans-(2′-hydroxycyclohexyl)-2-aminomethylpyridine ( 1) forms ML 2 complexes with M(II)?=?Cu, Ni, and Zn. X-ray crystal structures of the isostructural Ni(II) and Zn(II) complexes confirm bis-tridentate coordination in significantly distorted octahedral geometries as the all-cis facial isomer. Structural comparisons with the previously reported all-trans facial Cu(II) and cis,cis,trans(Npy) facial Co(III) complexes are presented. Protonation constants for 1 and stability constants with Cu(II), Ni(II), and Zn(II) are reported, with both ML and ML 2 species defined. The trend for ML (log K 1 values for Cu, Ni, and Zn of 8.3, 6.9, and 5.3, respectively) is conventional. Protonation and stability constants with Cu(II) for N,N-bis(2-pyridylmethyl)amine ( 2) were also defined. The log K 1 value measured for 2 of 7.4 is very similar to that found for 1 of 8.3, despite the marked difference in the third donor group; it appears that the third donor of the tridentate ligand generally binds only poorly to Jahn–Teller elongated Cu(II) in solution. 相似文献
11.
The kinetic and thermodynamic adsorption and adsorption isotherms of Pb(II) and Cu(II) ions onto H 2SO 4 modified chitosan were studied in a batch adsorption system. The experimental results were fitted using Freundlich, Langmuir and Dubinin–Radushkevich isotherms; the Langmuir isotherm showed the best conformity to the equilibrium data. The pseudo-first order, pseudo-second order and intraparticle diffusion kinetic models were employed to analyze the kinetic data. The adsorption behavior of Pb(II) and Cu(II) was best described by the pseudo-second order model. Thermodynamic parameters such as free energy change (Δ G°), enthalpy change (Δ H°) and entropy change (Δ S°) were determined; the adsorption process was found to be both spontaneous and exothermic. No physical damage to the adsorbents was observed after three cycles of adsorption/desorption using EDTA and HCl as eluents. The mechanistic pathway of the Pb(II) and Cu(II) uptake was examined by means of Fourier transform infrared (FTIR) and Energy dispersive X-ray (EDX) spectroscopy. The equilibrium parameter ( RL) indicated that chitosan–H 2SO 4 was favorable for Pb(II) and Cu(II) adsorption. 相似文献
12.
In this study, the formation constants of 1?:?1 binary complexes of Cu(II) with L-glutamic acid, L-aspartic acid, glycine, L-alanine, L-valine, and L-leucine and 1?:?2 binary complexes of L-glutamic acid, glycine and the protonation macro- and microconstants of all these amino acids were determined potentiometrically in aqueous solutions at 5.0, 20.0, and 35.0°C at a constant ionic strength of I?=?0.10?mol?L ?1 (NaClO 4). The thermodynamic parameters Δ G f°, Δ H f°, and Δ S f° were determined for the protonation of all amino acids used in this study and for the complex formation reactions of them with Cu(II). The results were analysed by means of Principle of hard and soft [ Lewis] acids and bases. Additionally, in order to confirm the complex formation and determine the stability constants of complexes, UV-Vis spectroscopic studies were carried out. The stability constants obtained by spectrophotometrically are confirmed by those determined potentiometrically. 相似文献
13.
Abstract Ternary copper(II) complexes of the type [Cu(His)A] (HisH= L-histidine, A=glycinato, L-valinato, L-alaninato, L-threoninato, L-serinato, or L-asparaginato) and [Cu(Glu)B] n- (GluH 2= L-glutamic acid, B=glycinato, L-alaninato, L-valinato ( n=1) or an amino-acid with positively charged protonated side chain such as L-asparagine, L-lysine, or L-ornithine ( n=0)) have been investigated in aqueous solution by means of ESR and absorption spectra. It is suggested that in the ternary species the histidinate ion adopts a histamine-like bonding mode giving rise to CuN 3O chromophores in the metal plane. Coordination in the bis-(glycine)-like mode is detected in the Glu-containing species. The spectral results have been used to postulate plausible structures for the bis-(histidinato)copper(II) complexes. 相似文献
14.
The thermal decomposition kinetics of sterically hindered salen type ligand ( L) and its metal complexes [ M=Co(II), Ni(II), Cu(II)] were investigated by thermogravimetric analysis. A direct insertion probe-mass spectrometer (DIP-MS)
was used for the characterization of metal complexes of L and all fragmentations and stable ions were characterized. The thermogravimetry and differential thermogravimetry (TG-DTG)
plots of salen type salicylaldimine ligand and complexes showed a single step.
The kinetic analysis of thermogravimetric data was performed by using the invariant kinetic parameter method (IKP). The values
of the invariant activation energy, E
inv and the invariant pre-exponential factor, A
inv, were calculated by using Coats-Redfern (CR) method. The thermal stabilities and activation energies of metal complexes of
sterically hindered salen type ligand ( L) were found as Co(II)>Cu(II)>Ni(II)> L and E
Cu> E
Ni> E
Co> L. Also, the probabilities of decomposition functions were investigated. The diffusion functions ( D
n) are most probable for the thermal decomposition of all complexes. 相似文献
15.
Formation constants (log K
MAL
MA) of the mixed complexes of the type M–A–L (where M=Mn(II), Co(II), Ni(II), Cu(II), Ce(III), Th(IV), and UO 2(II); A=oxine and L=sulphamerazine or sulphadiazine) have been determined pH-metrically in 60% ( v/ v) ethanol–water mixture at 25°C and constant ionic strength (μ=0.1 M NaCl). The mode of chelation was ascertained by conductivity
measurements. The stability sequence with respect to metal ions have been found to be Cu(II)>Ni(II)>Co(II)>Mn(II) and Th(IV)>UO 2(II)>Ce(III). CuAL ternary solid complexes have been prepared and characterized on the basis of elemental analysis and IR-spectroscopy.
The thermal degradations of the prepared complexes are discussed in an attempt to assign the intermediate compounds formed.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
16.
A new Cu(II)-ion imprinted polymer (IIP) has been synthesized by copolymerizing salicylic acid and formaldehyde as a monomer and crosslinker, respectively in the presence of Cu(II)-4-(2-pyridylazo) resorcinol complex. The imprinted Cu(II) ions were completely removed by leaching the IIP with 0.05 M EDTA. The maximum adsorption capacity for Cu(II) ions was 310 μg g−1 at pH 6. The IIP was repeatedly used in adsorption–desorption experiments for seven times with recoveries ~95%. The relative selectivity factor (α
r) values of Cu(II)/Zn(II), Cu(II)/Cd(II), Cu(II)/Ni(II) and Cu(II)/Co(II) are 3.17, 2.90, 2.47 and 3.37, respectively. The detection limit corresponding to three times the standard deviation of the blank was found to be 3.0 μg L−1. The developed IIP has also been tested for preconcentration and recovery of Cu(II) ions from water samples. 相似文献
17.
Conditional stability constants for the Cu-sensitive fluorescent dye Phen Green™ SK (PGSK) were determined for complexes containing both Cu(I) and Cu(II). Experimental conditions were optimized to minimize oxidation of Cu(I) to Cu(II). A binding constant of 10 11.38 for PGSK and Cu(I) was determined using chloride as the competing ligand and an iterative procedure involving equilibrium calculations to fit experimental data. The new constant was tested by evaluating PGSK fluorescence in the presence of the strong Cu(I)-ligand neocuproine and thiourea. There was good agreement between experimental data and changes in fluorescence predicted by calculations using the new constant and published constants for the competing ligands. Using EDTA to buffer the free ion concentration of Cu 2+, the conditional stability constant of PGSK with Cu(II) was measured to be 10 9.8. Both of these new constants are significantly higher than previously published values. Finally PGSK was used to examine the kinetics of Cu(I) dissociation from the biologically important ligand glutathione. 相似文献
18.
The polydentate ligands, 3-(2-aminocyclohexylamino)-2-(2-aminocyclohexyl aminomethyl) propionic acid ( L1 ), 4,7,10-triazatridecanedinitrile trihydrochloride ( L2 ), and 2,2′-(ethane-1,2-diyl) bis(methylazanediyl) diethanol ( L3 ) were prepared and their structures investigated by FT-IR, NMR, and MS. The kinetics of complex formation between Cu(II) and L 1, L 2, and L 3 were investigated in acidic aqueous solutions using the stopped-flow method. The stability constants of the complexes were determined by spectrophotometric titration (T?=?293?K, μ?=?0.1?mol?L ?1 NaClO 4), using a diode array UV-Vis spectrophotometer equipped with peristaltic pump and pH meter. The stability constants for the complexes were CuL 1?>?CuL 2?>?CuL 3. Activation enthalpies (ΔH#) of these complexes were 55?kJ?mol ?1 for CuL 1, 61?kJ?mol ?1 for CuL 2, and 36?kJ?mol ?1 for CuL 3, respectively. 相似文献
19.
Cu (II) complexes with the sterically hindered diphenol derivatives 3,5-di( tert-butyl)-1,2-benzenediol ( I), 4,6-di( tert-butyl)-1,2,3-benzenetriol ( II) and the sulfur-containing 4,6-di( tert-butyl)-3-(2-hydroxyethylsulfanyl)-1,2-benzenediol ( III) and 2-[4,6-di( tert-butyl)-2,3-dihydroxyphenylsulfanyl]acetic acid ( IV) have been synthesized and characterized by elemental analysis, TG/DTA, FT-IR, ESR, XPS, XPD and conductivity measurements.
Compounds I–III can coordinate in their singly deprotonated forms and act as bidentate ligands. These compounds yield Cu ( II) complexes of the stoichiometry Cu(L) 2, which have square planar geometry (g | > g ⊥ > g e). Unlike them, compound IV behaves as a terdentate ligand, and its complex Cu(L IV) 2 has distorted octahedral geometry. According to ESR data, only the Cu(L II) 2 complex contains a very small amount of phenoxyl radicals. Antimicrobial activities of these ligands and their respective
Cu (II) complexes have been determined with respect to Gram-positive and Gram-negative bacteria, as well as on yeasts. Their
phytotoxic properties against Chlorella vulgaris 157 were also examined. 相似文献
20.
The synthesis and structure of two Cu(II) complexes, {[Cu 2(L 1) 2]?·?DMF} n ( 1) and [CuL 2(phen)] ( 2), are described. The dinegative hydrazones are obtained by deprotonation of both phenolic and amide moieties of N′-(5-bromo-2-hydroxybenzylidene)-3,5-dimethoxybenzohydrazide (H 2L 1) and N′-(2-hydroxybenzylidene)pyrazine-2-carbohydrazide (H 2L 2). In each complex the planar ligand binds the metal ion via phenolate-O, imine-N, and amide-O. Complex 1 is a polymer in which phenoxo-bridged binuclear Cu(II) units are further joined by equatorial–apical amide-O bridges. The Cu···Cu separations are 3.0306 and 3.8217?Å for the phenolate-O bridged pair and the amide-O bridged pair, respectively. Complex 2 is a monomer where chelating phen displays axial–equatorial bonding, with square-pyramidal Cu(II). 相似文献
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