Studies on 3,3′-dichloro-, 4,4′-dichloro- and 5,5′-dichloro,2-2′-dimethyldithizone and their reactions with metal ions

Three new derivatives of dithizone are reported, with their electronic and i.r. spectra, acidity constants and partition coefficients between 0.5 M sodium perchlorate and chloroform or carbon tetrachloride. The extraction equilibria with Cd, Co(II), Hg(II), Ni, Pb, Tl(I), Zn and Bi and the spectrophotometric characteristics of the extractable metal chelates are described. Complete extraction of these complexes requires higher pH than that needed with dithizone itself. The 4,4′-dichloroisomer is more efficient than the 3,3′ and 5,5′-isomers, or dithizone itself, for the separation of cadmium from zinc or cobalt from nickel.     

Studies on tetrachlorodithizone isomers and their applications to the extraction of metal ions

Six isomeric tetrachlorodithizones were synthesized and their electronic and i.r. spectra were measured. Their acid dissociation constants and partition coefficients between 0.5 M NaClO₄ solution and carbon tetrachloride are reported. Their extraction equilibria with Cd(II). Co(II), Cu(II), Hg(II), Ni(II), Pb(II), Tl(I), Zn(II) and Bi(III) and the spectrophotometric characteristics of the complexes formed are described. The 3,3',4,4'-tetrachloro isomer is spectrophotometrically more sensitive than dithizone for Zn, Pb, Hg(II) and Bi(III) whereas the 2,2',3,3'- and 2,2',5,5'-isomers are more sensitive for copper ions. For most of the metals tested, the tetrachlorodithizones allowed quantitative extraction at lower pH than is possible with dithizone.     

Metal chelate exchange in the organic phase-II Extraction and exchange constants of dithizonates and diethyldithiocarbamates

Dithizonates and diethyldithiocarbamates of Ag, Tl(I), Cu(II), Zn, Cd, Hg(II), Pb, Fe(II), Co(II), Ni, Pd(II), In(III), As(III), Sb(III), Bi, Se(IV) and Te(IV) have been prepared and their reactions in carbon tetrachloride have been studied spectrophotometrically. From the exchange constants determined, the extraction constants of metal diethyldithiocarbamates have been calculated. Where formation of mixed chelates has been observed, corresponding exchange constants have been determined. Finally, the influence of organic solvents (CCl(4), CHCl(3), C(6)H(6) and C(6)H(5)Cl) on the exchange reaction of zinc diethyldithiocarbamate with dithizone has been investigated.     

Studies with dithizone analogues-II Preparation and characterization of 2,2'-dichlorodithizone and the investigation of its reactions with some metal ions

1,5-Di-(2-chlorophenyl)-3-mercaptoformazan (2,2'-dichlorodithizone) has been synthesized and characterized. Its acid dissociation constant and its partition coefficient between carbon tetrachloride and water have been determined. The introduction of chlorine atoms into the ortho positions of the phenyl nuclei of dithizone was found to affect the visible electronic spectra of the reagent and its metal complexes. The ranges of pH for complete extraction, and the extraction constants, for the Hg(II), Cu(II), Zn(II), Cd(II), and Pb(II) complexes have been determined. The stability constants of the Cu(II) and Zn(II) complexes were also determined. Discrepancies between the present extensive data and the corresponding earlier data have been attributed to use of impure materials and/or inaccuracy of measurements in the earlier work.     

Studies with dithizone : Part 26. The interaction of thallium(III) with solutions of dithizone in organic solvents

The strong oxidising capacity of thallium(III) dominates its reaction with solutions of dithizone (H₂Dz) in organic solvents. When carbon tetrachloride is used as solvent, the unstable thallium(III) complex Tl(HDz)³ is found in the organic phase but it very quickly disproportionates to the thallium(I) complex [Tl(HDz)], and bis-1,5-diphenylformazan-3-yl-disulphide. This reaction is notably faster in chloroform, in which thallium(I) dithizonate is the first identifiable product. In contact with an acidic aqueous phase, thallium(I) dithizonate is reverted to regenerate dithizone in the organic phase and Tl⁺ ions appear in the aqueous phase. Organic solutions of the disulphide disproportionate spontaneously by first-order kinetics to give an equimolar mixture of dithizone and the mesoionic compound, 2,3-diphenyl-2,3-dihydrotetrazolium-5-thiolate: this change is much slower in carbon tetrachloride than in the more polar chloroform and is catalysed by both Tl⁺ and Tl³⁺. If thallium(III) is present in excess, the mesoionic compound is the principal oxidation product of the dithizone although a dication may also be formed. The mesoionic compound does not react with thallium(I) but forms a water-soluble 2:1 complex with thallium(III); partition of this complex into the organic phase is uninfluenced by chloride ions. Because of the large number of competing reactions, the composition of the reaction mixture at any stage of the reaction between thallium(III) and dithizone depends on the relative concentrations of the components, the order in which they are brought together, the time elapsed after mixing, the pH of the aqueous phase, and the nature of the organic solvent.     

A new method for simultaneous determination of Co(II), Ni(II) and Pd(II) as morpholine-4-carbodithioate complex by SPME-HPLC-UV system

A new approach for the analysis of Co(II), Ni(II) and Pd(II) as morpholine-4-carbodithioate (MDTC) complexes in aqueous medium by using solid phase microextraction (SPME)-high performance liquid chromatography (HPLC)-UV has been developed. The method involves sorption of metal complexes on PDMS fiber from aqueous solution followed by desorption in the desorption chamber of SPME-HPLC interface using acetonitrile:water (60:40) as mobile phase. A good separation of metal complexes is achieved on C₁₈ column. The detection limits of Co(II), Ni(II) and Pd(II) are 0.17, 0.11 and 0.06 ng ml⁻¹, respectively. These can be determined by the proposed method without interference from other common metal ions such as Mo(VI), V(V), Ag(I), Sn(IV), Cd(II), Pb(II), Zn(II), Ag(I), Sn(II), Cr(III) and Cr(VI). The method was applied to the determination of these metals in different alloy samples and drinking water sample.     

Synthesis and Characterization of 2,4,6-tris(hydrazino)-s-triazine and its Metal Complexes

A new multidentate ligand related to s-triazine herbicides 2,4,6-tris(hydrazino)-s-triazine (THSTZ) and its metal complexes was synthesized. The complexes were investigated by m.s., n.m.r., i.r., u.v.–vis and AA spectroscopic techniques. Furthermore, carbon, nitrogen, hydrogen, chloride, and metal analyses, conductivity, magnetic susceptibility measurements, and thermal analyses were carried out. The Co(II), Ni(II), Cu(I), and Zn(II) metal complexes were synthesized in methanolic media. Metal-to-ligand ratios were found to be 1:1 for Co(II) and Zn(II), 2:1 for Cu(I) and 3:2 for Ni(II) complexes. N.m.r. spectral and thermal analyses showed the presence of MeOH in all of the complexes. Conductivity measurements suggested that the complexes were 1:2 electrolytes. Ring nitrogens as well as the terminal nitrogens of hydrazine side chains in THSTZ were proposed as metal binding centres. Magnetic moments of Ni(II) (4.12μ_B) and Co(II) (4.2μ_B) indicate tetrahedral and octahedral geometry, respectively. Tetrahedral geometry for Cu(I) and Zn(II) complexes was suggested. V. J. T. Raju - Previously working as Professor of Chemistry, Osmania University, Hyderbad, India     

Spectrophotometric extractive titrations-IV Determination of zinc in germanium dioxide and germanium chloride

A simple and selective determination of zinc in germanium chloride and germanium dioxide is described. The sample is dissolved in sodium potassium tartrate solution and zinc is titrated spectrophotometrically at 532 mug( with a dithizone solution in carbon tetrachloride without discarding the organic phase. Interfering ions such as Bi(III), Cu(II), Cd(II), Co(II), Ni(II), Pb(II), Sn(II), Fe(II), Fe(III), Mn(II) and T1(I) are masked with bis(2-hydroxyethyl)dithiocarbamate. The detection limit is 3-23 x 10(-5)% of zinc and this may be lowered by taking a larger sample and by performing the analysis in a closed system. A simplified technique, consisting of the simultaneous titration of the sample and blank, is described.     

Thermal and spectral studies on complexes derived from tetradentate Schiff bases

Several new complexes of Schiff bases ligands H₄La and H₄Lb with transition metal ions such as Cr(III), Fe(III), Co(II) and Zn(II) are synthesized. Elemental analysis, infrared, UV–Vis and thermal analysis, as well as conductivity and magnetic susceptibility measurements are used to elucidate the structure of the newly prepared metal complexes. A square planar geometry is suggested for Zn(II) complexes, while an octahedral geometry suggested for the Cr(III), Fe(III) and Co(II) complexes. The thermal decomposition of complexes was found to be first order reaction and the thermodynamic parameters corresponding to the different decomposition steps were reported.     

Adsorption of metal ions on activated carbon from aqueous solutions at pH 1-13

Adsorption of microgram amounts of 20 metal species on activated carbon powder from aqueous solutions of pH 1-13 was investigated. The species examined were Cs(I), Y(III), Ce(III), Ti(IV), Zr(IV), Cr(III), Cr(VI), Mn(II), Fe(III), Co(II), Ni(II), Ru(III), Cu(II), Ag(I), Zn(II), Cd(II), Al(III), Pb(II), Sb(III) and Bi(III).     

The reactions of diphenylcarbazide and diphenylcarbazone with cations : Part V. Extraction dissociation constants of the carbazone complexes

Extraction experiments in the system water-toluene on the diphenylcarbazone complexes of Mn(II), Fe(II) and (III). Co(II), Ni(II), Cu(ll), Zn(ll), Cd(II), Hg(I) and (II), Sn(II) and Pb(II) are described. Only uncharged complexes are formed, the formulae of which are for mercury HgD, Hg(HD)₂, Hg₂D and Hg₂(HD)₂ and for the other ions mentioned M(HD)_n, depending on the valence _n of the cation. The extraction dissociation constants, the molar extinction coefficients and the partition coefficients of the complexes funned by the cations studied were obtained, The complexes prove to be far less stable than the corresponding dithizone compounds so that diphenylcarbazone is less suitable for general analytical use than its sulphur analogue.     

Complexes of cytotoxic chelators from the dipyridyl ketone isonicotinoyl hydrazone (HPKIH) analogues

In an effort to better understand the antiproliferative effects of the tridentate hydrazone chelators di-2-pyridyl ketone isonicotinoyl hydrazone (HPKIH) and di-2-pyridyl ketone benzoyl hydrazone (HPKBH), we report the coordination chemistry of these ligands with the divalent metal ions, Mn, Co, Ni, Cu, and Zn. These complexes are compared with their Fe(II) analogues which were reported previously. The crystal structures of Co(PKIH)(2), Ni(PKIH)(2), Cu(PKIH)(2), Mn(PKBH)(2), Ni(PKBH)(2), Cu(PKBH)(2), and Zn(PKBH)(2) are reported where similar bis-tridenate coordination modes of the ligands are defined. In pure DMF, all complexes except the Zn(II) compounds exhibit metal-centered M(III/II) (Mn, Fe, Co, Ni) or M(II/I) (Cu) redox processes. All complexes show ligand-centered reductions at low potential. Electrochemistry in a mixed water/DMF solvent only elicited metal-centered responses from the Co and Fe complexes. Remarkably, all complexes show antiproliferative activity against the SK-N-MC neuroepithelioma cell line similar to (HPKIH) or significantly greater than that of the (HPKBH) ligand which suggests a mechanism that does not only involve the redox activity of these complexes. In fact, we suggest that the complexes act as lipophilic transport shuttles that allow entrance to the cell and enable the delivery of both the ligand and metal which act in concert to inhibit proliferation.     

Coordination complexes bearing potentially tetradentate phenoxyamine ligands

A series of metal complexes containing potentially tetradentate phenoxyamine ligands is described. The ligands are found to bind to main-group metals and first-row transition-metal centres with variable denticity depending upon the requirements of the particular metal centre. Bidentate [Al(III)], tridentate [Mg(II), Ca(II), Zn(II)] and tetradentate [K(I), Cr(III), Fe(II), Co(II)] binding modes have been established unambiguously through single-crystal X-ray structure determinations.     

Separation selectivity of anionic metal complexes of N,N'-bis(hydroxybenzyl)ethylenediamine-N,N'-diacetic acid in ion and ion electrokinetic chromatography

The complexes of Fe(III), Co(III), Mn(III), Al(III), Cu(II), Ni(II), Cd(II) and Zn(II) with N,N'-bis(hydroxybenzyl)ethylenediamine-N,N'-diacetic acid (HBED) were separated by ion exchange in different modes: ion chromatography (IC) and ion electrokinetic chromatography (IEKC). In column IC these complexes were separated on an IonPac AS4a anion-exchange column (Dionex, USA). Parameters of the background electrolyte that were examined in IEKC mode include polymer, competing ion concentration and pH. The use of poly(diallyldimethylammonium chloride) (PDADMACl) as a modifier in IEKC provides separation selectivity only slightly different from that observed in IC on the IonPac AS4a column. Optimal separation conditions were found to be: 0.1 mM HBED, 50 mM PDADMAOH, 10 mM Na2 B4 O7, pH adjusted to 10 with acetic acid. The use of an aromatic ligand allowed a 10-fold decrease in detection limits of metal ions in comparison with previously studied EDTA. A separation efficiency up to 400,000 theoretical plates was demonstrated for IEKC.     

Salisaldehyde-2-aminobenzimidazole schiff base complexes of Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II)

New metal complexes of Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) with salicylidine-2-aminobenzimidazole (SABI) are synthesized and their physicochemical properties are investigated using elemental and thermal analyses, IR, conductometric, solid reflectance and magnetic susceptibility measurements. The base reacts with these metal ions to give 1:1 (Metal:SABI) complexes; in cases of Fe(III), Co(II), Cu(II), Zn(II) and Cd(II) ions; and 1:2 (Metal:SABI) complexes; in case of Ni(II) ion. The conductance data reveal that Fe(III) complex is 2:1 electrolyte, Co(II) is 1:2 electrolyte, Cu(II), Zn(II) and Cd(II) complexes are 1:1 electrolytes while Ni(II) is non-electrolyte. IR spectra showed that the ligand is coordinated to the metal ions in a terdentate mannar with O, N, N donor sites of the phenloic -OH, azomethine -N and benzimidazole -N3. Magnetic and solid reflectance spectra are used to infer the coordinating capacity of the ligand and the geometrical structure of these complexes. The thermal decomposition of the complexes is studied and indicates that not only the coordinated and/or crystallization water is lost but also that the decomposition of the ligand from the complexes is necessary to interpret the successive mass loss. Different thermodynamic activation parameters are also reported, using Coats-Redfern method. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effect of the Nature of Crosslinking Agent on the Catalase‐Like Activity of Polystyrene‐Bound Glycine–Metal Complexes

Abstract

Catalase‐like activity of metal complexes of various crosslinked polystyrene‐supported glycines were carried out and correlated with the nature of crosslinking agent in the polymer support. Polystyrenes with 2 mol% divinyl benzene (DVB), ethylene glycol dimethacrylate (EGDMA), and 1,6‐hexanediol diacrylate (HDODA) crosslinking were used as polymer supports. Glycine functions were incorporated to the chloromethylpolystyrenes by polymer analogues reactions and complexed with Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), and Zn(II) ions. The metal uptake varied in the order: Cu(II) > Cr(III) > Mn(II) > Co(II) > Fe(III) > Ni(II) > Zn(II), and extent of metal uptake by various crosslinked systems varied with the nature of crosslinking agent. The polymeric ligands and the metal complexes were characterized by various analytical techniques. The catalytic activities of these metal complexes were investigated towards the decomposition of hydrogen peroxide and was found to decrease in the order: Co(II) > Cu(II) > Ni(II) > Cr(III) > Fe(III) > Mn(II) > Zn(II). With increasing rigidity of the crosslinking agent the catalytic activity also decreased.     

Surface layer-by-layer chemical deposition reaction for thin film formation of nano-sized metal 8-hydroxyquinolate complexes

The feasibility of a novel and simple layer-by-layer chemical deposition method for the preparation of nano-sized metal 8-hydroxyquinolate complexes has been investigated and reported. Uniform nanocrystalline films have been synthesized via dipping a substrate alternately in metal ion solution followed by ligand solution. The stoichiometry of the as-grown anhydrous Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) complex crystals were confirmed from the metal analysis and molar stoichiometric ratio of metal ion to 8-hydroxyquinoline. This was characterized as 1:2 for the Co(II), Ni(II), Cu(II) and Zn(II)–quinolate complexes. The Fe(III)–quinolate thin film was found to exhibit a 1:3 ratio. Electron impact-mass spectra (EI-MS) of all the synthesized thin film metal quinolate complexes were recorded and the results refer to the existence of the molecular ion peak at the corresponding m/z values. Confirmation of such stoichiometric 1:2 and 1:3 ratios were also evident from the (EI-MS) study. The deposited thin films were also subjected to analysis by a scanning electron microscope (SEM) and a particle size ?50 nm was detected. FT-IR and UV–Vis spectroscopy were further used to confirm the structure of the metal 8-hydroxyquinolate complexes. Thermal gravimetric analysis (TGA) was also used to follow up the possible thermal decomposition steps and to calculate the thermodynamic parameters of the nano-sized metal complexes.     

Separation and analysis of aluminium(III) by cation exchange ion chromatography

A method for the determination of aluminium(III) ions based on separation by cation exchange column chromatography and detection by conductivity detector has been developed. It is fast and reliable, and can be used for the separation and analysis of aluminium(III) ions from other metal ions like Mg(II), Mn(II), Zn(II), Co(II), Ca(II), Sr(II), rare earth elements like Lu(III), Tm(III), and Gd(III), which are eluted at different times and so do not interfere. Effect of p-phenylene diamine concentration present in the eluent, presence of other metal ions and effect of various anions present in the injection sample on the separation and analysis of aluminium(III) ions have also been studied.     

Non-aqueous,reversed-phase,high-performance,thin-layer chromatography and column liquid chromatography of metal complexes of porphine

Summary The chromatographic mobility of 21H, 23H-porphine and its Ni(II), Cu(II), Zn(II) and Pd(II) complexes were investigated by high-performance thin-layer chromatography on an octadecyl-bonded, silica gel plate with various polar organic solvents including alcohols, acetonitrile, dimethylsulfoxide and propylenecarbonate. The mobility generally decreases according to the central metal ion of the complex as follows: Zn(II)>(free porphine)>Ni(II)>Pd(II)>Cu(II). Methanol is a good choice of solvent for the separation of these metal porphine complexes. Successful separation of porphine and the four metal complexes is accomplished within 13 min on a LiChrosorb RP-18 column with methanol eluent.     

Preparation, characterization and application of an cellulose ion-exchanger with acetoacetamide functional groups

Summary A method is described for functionalizing acetoacetamide chelating groups onto microcrystalline cellulose (Cell-AcAc). This material shows a significant affinity for Fe(III), Cu(II) and U(VI) and no or very less affinity for the M(I) ions (M=Na, K), M(II) ions (M= Mg, Ca; Fe, Co, Ni, Zn), La(III) and Y(III) including Th(IV). The obtained K _d values offer a column separation method for U(VI) ions from the rest of above-mentioned metal ions except Fe(III). Cell-AcAc and its Cu(II) complexes are characterized by means of FT-IR spectra.

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Darstellung, Charakterisierung und Anwendung von Ionenaustauschmaterial aus Cellulose mit chemisch gebundener Acetoacetamid-Gruppe

Zusammenfassung Die Darstellung von immobilisiertem Acetoacetamid auf mikrokristallinem Cellulosepulver (Cell-AcAc) wird beschrieben. Der Ionenaustauscher Cell-AcAc hat eine ausgeprägte Affinität für Fe(III), Cu(II) and U(VI), aber nahezu keine für die M(I)-Ionen (M=Na, K) M(II)-Ionen (M=Mg, Ca; Fe, Co, Ni, Zn), La(III), Y(III) sowie Th(IV). Die erhaltenen K _d-Werte ermöglichen für U(VI)-Ionen eine quantitative säulen-chromatographische Trennung von den anderen genannten Kationen mit Ausnahme von Fe(III). Das Ionenaustauschmaterial Cell-AcAc und sein Cu(II)-Komplex wurden durch FT-IR-Spektren charakterisiert.