COMPLEXES OF Al(III) WITH HYDROXYAROMATIC LIGANDS

Abstract

In order to assess the aluminium binding ability of humic and fulvic acids, important organic soil constituents, a pH-potentiometric study was made of the proton and aluminium(III) complexes of various bi-, tri- and tetradentate catechol and salicylic acid derivatives at 25°C and at an ionic strength of 0.20moldm^?3 (KC1). The stability data revealed that at low pH the salicylate function, and at high pH the catecholate function, is preferentially bound to the aluminium ion. In the intermediate pH range, mixed hydroxo complexes and other di/oligomeric species are also formed. With an increase of the number of available coordinating sites in the molecule, the tendency to oligomeric complex formation increases, while the tendency to metal ion hydrolysis decreases.     

TRANSITION METAL COMPLEXES OF AMINOPHOSPHONIC ACID ANALOGUES OF METHIONINE AND ALANINE IN AQUEOUS SOLUTION

Abstract

The stoichiometrics and stability constants of the nickel(II), copper(II) and zinc(II) complexes of l-amino-3-methylthiopropanephosphonic acid (MetP) and 1-amino-ethanephosphonic acid (a-AlaP) have been determined pH-metrically at 25°C at an ionic strength of 0.2 mol dm^?3 (KC1). From the stability data and the absorption spectra of the complexes it has been established that simple aminophosphonic acids coordinate to the nickel(II) and copper(II) ions forming chelate complexes in which the metal binding mode is bidentate with the {NH₂, PO₃ ^2-} donor set. ³¹P and ¹H NMR measurements showed that MetP and α-AlaP exhibit similar properties in the presence of zinc(II) ions, but the ligand reacts to form a cyclic phosphonoamidate in neutral and slightly alkaline solution in the Zn(II)-α-AlaP system and at slightly acidic conditions in the Zn(II)-MetP system. This difference reveals that the latter ligand at pH > 7 prefers Zn(II) coordination involving all possible (amino, phosphonate and thioether sulfur) donor groups.     

SYNTHESIS,PROPERTIES AND BIOLOGICAL ACTIVITY OF RARE EARTH COMPLEXES OF 5-FLUOROURACIL-1-PROPIONIC ACID

Abstract

Seven new solid complexes of 5-fluorouracil-1-propionic acid with rare earth metals have been synthesized. Elemental analyses, molar conductance, TG-DTA, IR, UV-Vis, fluorescence, XPS and ¹H NMR spectra have been used to characterize these complexes. The general formula of the complexes is RE(FPA)₃. nH₂O where RE = Y(III), La(III), Pr(III), Sm(III), Eu(III), Dy(III), Er(III); n=3 or 5. Prooxidative and antitumor activity of these complexes was tested. The results showed that these complexes augment free radical generation; especially the Pr³+ complex which obviously increased the O₂ ^? and OH^? radicals. It was also found that La³+ and Y³+ complexes possess antitumor effects on human colon bladder HCT-B and human leukemia HL-60 cells in vitro.     

Complex formation of indium(<Emphasis Type="SmallCaps">iii</Emphasis>) with citric acid in aqueous solution

Complex formation of In³⁺ ion with citric acid in an aqueous solution was studied by pH-metric titration at the molar ratio of the reactants [In³⁺] : [H₄Cit] = 1 : 1, 1 : 2, and 1 : 3 in a range of pH 2—10. The mathematical simulation of equilibria in an indium(iii)—citric acid system was performed using the CPESSP program package. The formation of 1 : 1, 1 : 2, and 1 : 3 indium(iii) citrate complexes with different degrees of nuclearity and protonation was established. The equilibrium constants of formation of the complexes were calculated. The predomination of the polynuclear indium(iii) citrate complexes at the equimolar metal to ligand ratio of was observed in almost the whole pH range studied (3—10).     

溶液中N-乙酸基取代氮氧杂大环及其配合物稳定性研究

用pH电位滴定法在25℃,0.5mol·L^-1KNO₃水溶液中测定了三种大环化合物:H₂L¹(1,12-二氮杂-3,4:9,10-二苯并-5,8-二氧杂环十五烷-N,N'-二乙酸);H₃L²(1,12,15-三氮杂-3,4:9,10-二苯并-5,8-二氧杂环十七烷-N,N',N″-三乙酸)和H₂L³(1,15-二氮杂-3,4:12,13-二苯并-5,8,11-三氧杂环十八烷-N,N′-二乙酸)的逐级质子化常数.又测定了它们与Cu²⁺、Ni²⁺、Pb²⁺配合物的稳定常数,以及H₂L³与镧系金属La³⁺、Pr³⁺、Nd³⁺、Eu³⁺、Sm³⁺、Gd³⁺、Dy³⁺、Yb³⁺配合物的稳定常数.讨论了三种大环化合物质子化的一般顺序及其与各种离子配位时稳定性选择规律.说明了影响配位稳定性的有关因素.     

PREPARATION AND PROPERTIES OF PYRIDINE DICARBOXYLIC ACID COMPLEXES OF THE LANTHANIDES

Abstract

The preparation and spectroscopic properties of eleven hydrated lanthanide (III) dipicolinate and quinolinate complexes are reported for the first time. The complexes are of three general types: M(dipi)(dipiH)(H₂O)₄, M(dipiH)₃(H₂O) and M(quin)(quinH)(H₂O)₃ [where M =lanthanide (III); dipiH₂ =pyridine-2,6-dicarboxylic acid (dipicolinic acid); quinH₂ =pyridine-2, 3-dicarboxylic acid (quinolinic acid)], and evidence is presented which indicates that they may be six-coordinate.     

COMPLEXES OF BINUCLEATING LIGANDS. XIII. SOLUBLE COMPLEXES OF A LIGAND WITH A BRIDGING THIOPHENOXIDE COMPONENT AND PERIPHERAL n-OCTYL SUBSTITUENTS

Abstract

The trianionic binucleating ligands formally derived from the condensation products of S-n-octyldithiocarbazate with either 2-hydroxy- or 2-mercapto-5-methylisophthalaldehyde (hereafter (L″)^3- and L^3- respectively) gave the binuclear complexes L″Ni₂ (CH₃ O), L″Ni₂ (C₆ H₅ CH₂ O), LNi₂ (C₃ H₃ N₂), LCu₂ (C₃ H₃ N₂) and LNi₂ (SR) where R=C₈H_{1 7} of CH₃.C₆ H₄ and C₃ H₃ N₂ ^?=the pyrazolate anion. These complexes were soluble in chloroform and ¹H n.m.r. data for some of them are presented. There was no evidence for significant magnetic exchange within LCu₂ (C₃ H₃ N₂). Attempts to generate LNi₂ (X) where X^?=Cl^?, Br^? or I^? gave L₂ Ni₃ in which L^3- fails to impose the intended molecular arrangement. Attempts to generate L(Pd(II))₂ (X) unexpectedly gave materials containing additional palladium, i.e. LPd₄ (CH₃ CO₂) and LPd₄ (C₃ H₃ N₂).     

COMPLEXES OF BINUCLEATING LIGANDS. VII. SOME COPPER(II) COMPLEXES OF TWO SULPHUR-CONTAINING LIGANDS

Abstract

The following cupric complexes of the new binucleating ligand 2-hydroxy-5-methylisophthalaldehyde di-2′-methyl-mercaptoanil, (hereafter MeLH, the ligand strictly being the derived anion MeL^?) and of the related trianionic ligand (hereafter L^3-) formally derived from 2-hydroxy-5-methylisophthalaldehyde di-2′-mercaptoanil have been isolated and characterized:- Cu₂(MeL)Cl₃, Cu₂(MeL)Br₃, Cu₃(MeL)Br₅, Cu₂(MeL)(OH)(ClO₄)₂, Cu₂(L)Cl · DMSO, Cu₂(L)(NCO), Cu₂(L)(tz) (where tz is the anion of 1,2,4-triazole (tzH)). Magnetic properties are consistent with binuclear arrangements in all cases except Cu₃(MeL)Br₅.     

INFRARED SPECTROSCOPIC STUDIES OF SOME URANYL NITRATE COMPLEXES

Abstract

The infrared spectra of ammonium, potassium, rubidium and cesium uranyl trinitrates (NH₄UO₂(NO₃)₃, KUO₂(NO₃)₃, RbUO₂(NO₃)₃ and CsUO₂(NO₃)₃) have been measured in the region from 4000 cm^?1 down to 30 cm^?1. A normal coordinate analysis of the complexes has been made as a six-body problem (UO₂ X₃) (X=NO₃) neglecting the outer cations. Force constants of U-O and U-X bonds in UO₂X₃ anion have been approximately obtained on the basis of a modified valence force field including an additional force constant of opposite U[sbnd]O bond-bond interaction. In addition, bond order of the uranyl bonds of the complexes has been determined from the U[sbnd]O stretching force constants and compared with those of other uranium compounds such as metal uranates and uranium oxides.     

SYNTHESIS AND CHARACTERIZATION OF NEW OXODIPEROXOVANADATE COMPLEXES CONTAINING COORDINATED AMINOACIDS

Abstract

The study of peroxovanadium compounds has received renewed attention since the discovery of their insulin mimetic properties and of the vanadium bromoperoxidase enzyme which catalyzes the oxidation of halides by hydrogen peroxide. This work presents the synthesis and characterization of three novel oxodiperoxovanadium complexes, K _n [VO(O₂)₂AA] 2H₂O, where AA = L-asparagine(l), L-phenylglycine(2), D, L-homocystine(3). The products were synthesized by the reaction of V₂O₅, with the amino acid and H₂O₂ at room temperature. The compounds obtained are yellow, soluble in water and insoluble in organic solvents. They show remarkable hygroscopic character and are light and temperature sensitive. IR and UV-VIS spectra of the compounds show the typical oxo and diperoxo bands (ν_v = o = 970 cm^?1, ν_vo-o = 870cm^?1, νv-O₂ = 630, 525 cm^?1, ? ?320nm). The ligand bonding properties were determined on the basis of electric conductivity and spectroscopic data (IR, ¹H NMR) as well as elemental analysis.     

ELECTRONIC STRUCTURE OF CYANO-BRIDGED DINUCLEAR IRON COMPLEXES

Abstract

A series of complexes of formula [(NC)₅Fe^II—NC—Fe^II(CN)₄L]^n?, with L = H₂O, pyridine, isonicotinamide and 4-cyanopyridine were prepared in aqueous solution by substitution of the corresponding [Fe^II(CN)₅L]^n? ions into [Fe^II(CN)₅H₂O]^3?. The mixed valent (II, III) and fully oxidized (III, III) complexes were also obtained. The (II, II) complexes were moderately stable toward dissociation into the mononuclear species, but the mixed-valent ions were properly characterized by UV-vis-NIR spectroscopy and electrochemistry. Distinctive intervalence (IV) bands were assigned in the NIR region, with the energy being dependent on the binding properties of L; the IV band energy also correlated with the redox potential at the [NC—Fe(CN)₄L] fragment. By application of the Hush model, a valence-trapped situation was found for the [(NC)₅Fe^III—NC—Fe^II(CN)₄L]^n? ions. The class II behavior shows, however, a value of H _ab, the electronic coupling factor, of ca. 1600cm^?1, indicating a moderate-to-strong communication between the metal centers.     

SYNTHESIS AND CHARACTERISATION OF DIORGANOANTIMONY(III) COMPLEXES OF THIOSEMICARBAZONES

Abstract

The interaction of the sodium salts of thiosemicarbazones with diphenylantimony chloride in 1:1 molar ratio in benzene solution lead to the formation of derivatives, Ph₂Sb[SC(NH₂)NN: C(R)R′] where R = H; R′ [dbnd] C₆H₅, CH₃OC₆H₄, C₆H₅CH[dbnd]CH, and R′ [dbnd] CH₃; R′[dbnd]C₆H₅, CH₃OC₆H₄, C₆H₄CH₃, respectively. The resulting complexes have been characterised on the basis of elemental analyses and molecular weight determination. The mode of bonding of the ligands with the metal atom has been proposed on the basis of I.R., ¹H and ¹³C NMR studies. All these ligands are found to behave as monofunctional bidentate moiety in these complexes.     

SYNTHESIS AND ELECTROCHEMICAL PROPERTIES OF CYCLOPENTADIENYLIRON(II) COMPLEXES WITH BIS(DIPHENYLPHOSPHINO)AMINE AS LIGAND

Abstract

The synthesis and properties of new cationic iron(II) complexes of general formula [(η⁵-C₅H₅)FeL(η²-dppa)]A [A=I^?, L = CO(1); A = BF₄, L = CO(2) CH₃CN(4), η¹-dppa(5); dppa = NH(PPh₂)₂] are described. The carbonyl complex [(η⁵-C₅H₅)Fe(CO)(η²-dppa)]BF₄ is deprotonated to give the neutral complex [(η⁵-C₅H₅)Fe(CO){η²-(PPh₂)₂N}](3). All complexes have been characterized by elemental analysis and IR and NMR spectroscopies. Cyclic voltammetry of complexes 1–5 shows a diverse redox chemistry in acetonitrile solution. While the reduction of 1 and 2 leads to the formation of a dinuclear Fe(I) complex, 4 and 5 form mononuclear species of Fe(I); oxidation of metal centers of 1 and 2 is not observed and in complexes 3 and 4 the metal centers are oxidized at potentials < 1. Complex 5 in acetonitrile solution is transformed into complex 4.     

ACCELERATED CLEAVAGE OF P-NITROPHENYL PICOLINATE CATALYZED BY COPPER(II) AND ZINC(II) COMPLEXES OF D-GLUCOSAMINE SCHIFF BASE IN MICELLAE SOLUTION

Abstract

The hydrolysis of p-nirrophenyl picolinate (PNPP) catalyzed by the Cu(II) and Zn(H) complexes of d-glucosamine schiff base was investigated kinetically by observing the rates of the release of p-nitrophenol in the buffered micellor solution at different pit and 25°C. The scheme for reaction acting mode involving a ternary complex contain ligand, metal ion and substrate in micelle was establish and the reaction mechanisms were discussed The experimental results indicated that the complexes catalyzed efficiently the hydrolysis of PNPP, especially Zn(II) complex. The rate constant k_N, which shows the catalytic reactivity of complexes, WBI determined to be 0.4251 s^?1 far Cu(II) complex at pH 7 60 in micellar solution. The catalytic reactivity of Zn(II) complex were much larger than Cu(II) complex, the k_N was determined to be 3.1914 s^?1 at same pH value.     

Indication Ion Square Wave Voltammetric Determination of Thiamine and Ascorbic Acid

Abstract

Cd²⁺ ion was used as an electrochemical indicator to detect V_B1 or Vc using square ware voltammetry (SWV) at a mercury film‐coated glassy carbon (GC) electrode. At pH=10 NH₃‐NH₄Cl buffer, a new cathodic peak was found at ?0.360 V (vs.SCE) by addition of thiamine, and the peak current of SWV was linear with the concentration of thiamine in the range of 1×10^?6 to 4×10^?3 M. On the other hand, the SWV peak current of Cd²⁺ at ?0.856 V linearly decreased with addition of ascorbic acid in the range of 6×10^?6～10^?3 M. The effects of interference, such as citric acid, DL‐malic acid, and calcium panlothenate, on thiamine or ascorbic acid determination were investigated. This method was successfully applied to the determination of thiamine or in pharmaceutical preparation.     

ASYMMETRIC SYNTHESIS OF PROLINE USING COBALT(III)-TETRAAMINE COMPLEXES

Abstract

The decarboxylation reaction of δ -cis-β-[Co(L₁)(pdH)]²⁺ complex yielded δ -cis-β-[Co(L₁) (R-pro)]²⁺, while the δ -cis-β-[Co(L₂) (S-pro)]²⁺ was obtained from the reaction of δ -cis-β-[Co(L₂) (pdH)]²⁺, where L₁ is (3R)3-methyl-1, 6-bis[(2S)-pyrrolidin-2-yl]-2, 5-diazahexane, L₂ is (3S) 3-methyl-1, 6-bis-[(2S)-pyrrolidin-2-yl]-2, 5-diazahexane, and pdH is the pyrrolidine-2, 2-dicarboxylate ion. The asymmetrically synthesized prolines were isolated via the decomposition of the decarboxylated complexes. The proline isolated from δ -cis-β-[Co(L₁) (R-pro)]²⁺ showed a specific rotation of +12.0, representing a 24% excess of R-proline over S-proline, while the proline isolated from δ -cis-β-[Co(L₂) (S-pro)]²⁺ showed a specific rotation of -10.0, indicating a 20% excess of S-proline over R-proline.     

SYNTHESIS AND PROPERTIES OF THE FIRST DISULFUR AND DISELENIUM COMPLEXES OF PLATINUM

The reactions of overcrowded platinum(0) complexes [Pt{P(Ar)Me₂}₂] (Ar = 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl (Tbt), 2,6-bis[bis- (trimethylsilyl)methyl]-4-[tris(trimethylsilyl)methyl]phenyl (Bbt)) with elemental sulfur and selenium resulted in the formation of the first platinum disulfur and diselenium complexes, [Pt(S₂){P(Ar)Me₂}₂] (4a (Ar = Tbt), 4b (Ar = Bbt) and [Pt(Se₂){P(Ar)Me₂}₂] (5a (Ar = Tbt), 5b (Ar = Bbt)) respectively. The x-ray crystallographic analyses of 4b and 5b showed a novel three-membered PtE₂ (E = S, Se) ring structure with a square planar geometry around the platinum center. The oxidation of 4b and 5b with an equimolar amount of m-chloroperbenzoic acid or tert-butyl hydroperoxide in dichloromethane yielded the corresponding disulfur and diselenium monoxide complexes [Pt(E₂O){P(Bbt)Me₂}₂] (6 (E = S), 7 (E = Se)). The further reactions of 6 and 7 with an excess of oxidants gave the corresponding O,S-coordinated thiosulfato complex [Pt(S₂ O₃){P(Bbt)Me₂}₂] (8) and the O,O-coordinated selenito complex [Pt(SeO₃){P(Bbt)Me₂}₂] (11), respectively. The dynamic behavior in solution was revealed by the variable-temperature NMR spectroscopy for 4b, 5b, 8, and 11, which indicates the existence of the intramolecular CH···E (E = O, S, Se) interactions between the methine hydrogens of the o-bis(trimethylsilyl)methyl groups and the Pt-bonded chalcogen atoms.     

THE EQUILIBRIA AND KINETICS OF THE COMPLEX FORMATION BETWEEN Fe(III) AND TARTARIC AND CITRIC ACIDS

Abstract

The equilibria and kinetics of formation of 1 : 1 iron(III) complexes with tartaric and citric acids have been studied in the pH range 1.0–2.0 in aqueous alcoholic perchlorate media. The equilibrium constants for the reactions Fe³⁺ +

H₄L^keq Complex + nH⁺ were obtained from spectrophotometric measurements in the wavelength range 360–420 nm. The values of K _eq determined at 20°, μ=1.0 M (water 100%), were 0.21 M with n=2 for tartaric and 0.0186 M² with n=3 for citric acid. The stoichiometry of the complex formation and the reaction sites of the ligands were discussed with reference to previous findings on ligands of related structures. The kinetics of the reactions were carried out by the stopped-flow technique. From the hydrogen ion dependence of the reaction rates it can be shown that complex formation occurs between FeOH²⁺ and differently protonated forms of the ligands. Forward rates for the different paths are consistent with an SN1 IP interaction in agreement with the Eigen mechanism; forward and reverse rate quotients enabled the evaluation of the equilibrium constants which agreed satisfactorily with the spectrophotometric ones. The effect of varying the solvent composition (water-alcohol) was discussed with reference to the reaction mechanism.     

Synthesis,characterization, DNA-binding,and antioxidant activities of four copper(II) complexes containing N-(3-hydroxybenzyl)-amino amide ligands

Four new substituted amino acid ligands, N-(3-hydroxybenzyl)-glycine acid (HL₁), N-(3-hydroxybenzyl)-alanine acid (HL₂), N-(3-hydroxybenzyl)-phenylalanine acid (HL₃), and N-(3-hydroxybenzyl)-leucine acid (HL₄), 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(L₁)₂]·2H₂O (1), [Cu(L₂)₂(H₂O)] (2), [Cu(L₃)₂(CH₃OH)] (3), and [Cu(L₄)₂(H₂O)]·H₂O (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.