Solvent extraction and bulk liquid membrane transport of Co(II) and Ni(II) ammine cations by proton-ionizable crown ethers

Separation efficiencies and selectivities in solvent extraction of Co(II) and Ni(H) ammine cations from aqueous solutions into chloroform and toluene and in transport through bulk toluene membranes by proton-ionizable crown ethers have been determined. Six proton-ionizable crown ethers with differing lipophilicities, polyether cavity sizes and ionizable groups (carboxylic and sulfonic acid functions) were examined. Higher selectivity and efficiency for Co(II) ammine cation extraction was observed for the more lipophilic, proton-ionizable crown ethers. Highly lipophilic crown carboxylic acids provided effective and selective transport of Co(II) ammine cations through bulk toluene membranes.Presented in part at the 6th International Symposium on High Purity Materials in Science and Technology: Preparation, Characterization and Application of Well-Defined Materials, Dresden, GDR, May 1985, Poster D91, Poster Abstracts, pp. 144, 145.All extraction and transport experiments were conducted at this location.     

Spectroscopic evaluation of Co(II), Ni(II) and Cu(II) complexes derived from thiosemicarbazone and semicarbazone

Co(II), Ni(II) and Cu(II) complexes were synthesized with thiosemicarbazone (L(1)) and semicarbazone (L(2)) derived from 2-acetyl furan. These complexes were characterized by elemental analysis, molar conductance, magnetic moment, mass, IR, electronic and EPR spectral studies. The molar conductance measurement of the complexes in DMSO corresponds to non-electrolytic nature. All the complexes are of high-spin type. On the basis of different spectral studies six coordinated geometry may be assigned for all the complexes except Co(L)(2)(SO(4)) and Cu(L)(2)(SO(4)) [where L=L(1) and L(2)] which are of five coordinated square pyramidal geometry.     

Cloud Point Extraction Simultaneous Spectrophotometric Determination of Zn(II), Co(II) and Ni(II) in Water and Urine Samples by 1-(2-Pyridylazo)2-Naphthol Using Partial Least Squares Regression

A cloud-point extraction (CPE) process using the nonionic surfactant Triton X-114 to simultaneous extraction and spectrophotometric determination of Zn(II), Co(II) and Ni(II) from aqueous solution using partial least squares (PLS) regression is investigated. The method is based on the color reaction of these cations with 1-(2-pyridylazo)2-naphthol and subsequent micelle-mediated extraction of products. The optimum extraction and reaction conditions such as pH, reagents concentration and effect of time have been studied. Linearity was obeyed in the range 2–150, 5–250 and 2–150 ng mL⁻¹ of Zn(II), Co(II) and Ni(II) respectively. The relative standard error (RSE) for the simultaneous determination of 15 test samples of different concentrations of Zn(II), Co(II) and Ni(II) was 4.38%;, 1.18% and 2.42%, respectively. The total relative standard error (RSE_t) for applying the PLS method to 15 synthetic samples in the linear ranges of these metals was 2.36%. The interference effect of some anions and cations was also tested. The method was applied to the simultaneous determination of Zn(II), Co(II) and Ni(II) in water and human urine samples.     

Coordination compounds of Co(II), Ni(II) and Cu(II) with capric acid hydrazide

The reaction of aquo-ethanolic solutions of Co(II), Ni(II) and Cu(II) salts and ethanolic solution of capric acid hydrazide (L) yielded paramagnetic, high-spin bis- and tris(ligand) chelate complexes. The tris(ligand) complexes, [ML ₃]X ₂·nH₂O [M=Co(II), Ni(II);X=NO ₃ ^– , ClO ₄ ^– , 1/2SO ₄ ^2– ], have an octahedral structure formed on account of the bidentate (NO) coordination of three neutral hydrazide molecules. In the bis(ligand) complexes,ML ₂(NCS)₂ [M=Co(II), Ni(II)] and CuL ₂ X ₂·nH₂O (X=NO ₃ ^– , ClO ₄ ^– and 1/2SO ₄ ^2– ), the oxoanions and NCS^– take also part in coordination. The complexes have been characterized by elemental analysis, IR spectra, magnetic measurements, molar conductivity and TG analysis.

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Caprinsäurehydrazid-Komplexe von Co(II), Ni(II) und Cu(II)

Zusammenfassung Durch die Reaktion von wäßrig-ethanolischen Lösungen von Co(II)-, Ni(II)-und Cu(II)-Salzen mit einer ethanolischen Lösung von Caprinsäurehydrazid (L) wurden paramagnetische high-spin Bis- und Tris-Ligand-Chelatkomplexe erhalten. Tris-Ligand-Komplexe des Typs [ML ₃ X ₂·nH₂O [M=Co(II), Ni(II);X=NO ₃ ^– , ClO ₄ ^– , 1/2SO ₄ ^2– ], die eine oktaedrische Struktur besitzen, entstehen durch die Koordination von drei neutralen zweizähnigen (NO)-Hydrazidmolekülen. Bei den Bis-Ligand-KomplexenML ₂(NCS)₂ [M=Co(II), Ni(II)], sowie bei den Bis-Ligand-Komplexen CuL ₂ X ₂·nH₂O (X=NO ₃ ^– , ClO ₄ ^– , 1/2SO ₄ ^2– ) nehmen bei der Koordination außer Hydrazid auch die Säurereste teil. Die Komplexe wurden durch Elementaranalyse, IR-Spektren, magnetische Messungen, molare Leitfähigkeit und TG-Analysen charakterisiert.

     

Synthesis and characterization of potassium 1,3-bis(N-methylpiperazino)propan-2-O-xanthate and the complexes of Co(II), Ni(II) and Cu(I) ions

Potassium 1,3-bis(N-methyl piperazino)propan-2-O-xanthate (LK), and its complexes with Co(II), Ni(II) and Cu(I) ions have been prepared and characterized as [CoL₂(H₂O)₂], [NiL₂(H₂O)₂]·2H₂O and CuL·2H₂O by FT-IR, ¹H and ¹³C?NMR spectroscopies, elemental analyses, magnetic susceptibility and TGA techniques.     

Characterization and TG-MS studies of lactato and bipyridine-lactato complexes of Co(II) and Ni(II)

Two lactates and four new mixed ligand complexes with formulae Co(lact)₂·2H₂O, Ni(lact)₂·3H₂O, Co(4-bpy)(lact)₂, Co(2,4'-bpy)₂(lact)₂, Ni(4-bpy)(lact)₂·2H₂O and Ni(2,4'-bpy)₂(lact)₂ (where 4-bpy=4,4'-bipyridine, 2,4'-bpy=2,4'-bipyridine, lact=CH₃CH(OH)COO^-) were isolated and investigated. The thermal behaviour of compounds was studied by thermal analysis (TG, DTG, DTA). In the case of hydrated complexes thermal decomposition starts with the release of water molecules. The compounds decompose at high temperature to metal(II) oxides in air. A coupled TG-MS system was used to analyse the principal volatile products of thermolysis and fragmentation processes of obtained complexes. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal and spectroscopic investigation of new binuclear Pt(II) complexes with carboxylic acids

The thermal decomposition of the binuclear Pt(II) complexes with acetate, propionate, valerate and izovalerate ligands were studied by TG and DTA techniques. The Pt(II) complex with acetic acid (PtAA) was stable up to 343.15 K, Pt(II) complex with propionic acid (PtPrA) was stable up to 323.15 K, Pt(II) complex with valeric acid (PtVA) was stable up to T=313.15 K and Pt(II) complex with isovaleric acid (PtIvA) was stable up to 408.15 K. The PtAA complex was investigated again after a year by thermogravimetric analysis. After the thermal decomposition of the Pt(II) complexes with carboxylic acids, only in the PtVA complex and PtAA complex (investigated after a year) the final residue contains only platinum, while in the rest complexes the solid residue was a mixture of platinum and platinum carbides (PtC₂, Pt₂C₃).     

Bioactive Co(II), Ni(II), and Cu(II) Complexes Containing a Tridentate Sulfathiazole-Based (ONN) Schiff Base

New Co(II), Ni(II), and Cu(II) complexes were synthesized with the Schiff base ligand obtained by the condensation of sulfathiazole with salicylaldehyde. Their characterization was performed by elemental analysis, molar conductance, spectroscopic techniques (IR, diffuse reflectance and UV–Vis–NIR), magnetic moments, thermal analysis, and calorimetry (thermogravimetry/derivative thermogravimetry/differential scanning calorimetry), while their morphological and crystal systems were explained on the basis of powder X-ray diffraction results. The IR data indicated that the Schiff base ligand is tridentate coordinated to the metallic ion with two N atoms from azomethine group and thiazole ring and one O atom from phenolic group. The composition of the complexes was found to be of the [ML₂]∙nH₂O (M = Co, n = 1.5 (1); M = Ni, n = 1 (2); M = Cu, n = 4.5 (3)) type, having an octahedral geometry for the Co(II) and Ni(II) complexes and a tetragonally distorted octahedral geometry for the Cu(II) complex. The presence of lattice water molecules was confirmed by thermal analysis. XRD analysis evidenced the polycrystalline nature of the powders, with a monoclinic structure. The unit cell volume of the complexes was found to increase in the order of (2) < (1) < (3). SEM evidenced hard agglomerates with micrometric-range sizes for all the investigated samples (ligand and complexes). EDS analysis showed that the N:S and N:M atomic ratios were close to the theoretical ones (1.5 and 6.0, respectively). The geometric and electronic structures of the Schiff base ligand 4-((2-hydroxybenzylidene) amino)-N-(thiazol-2-yl) benzenesulfonamide (HL) was computationally investigated by the density functional theory (DFT) method. The predictive molecular properties of the chemical reactivity of the HL and Cu(II) complex were determined by a DFT calculation. The Schiff base and its metal complexes were tested against some bacterial strains (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus subtilis). The results indicated that the antibacterial activity of all metal complexes is better than that of the Schiff base.     

Simultaneous kinetic spectrophotometric determination of Cu(II), Co(II) and Ni(II) using partial least squares (PLS) regression

A partial least squares (PLS-1) calibration model based on kinetic—spectrophotometric measurement, for the simultaneous determination of Cu(II), Ni(II) and Co(II) ions is described. The method was based on the difference in the rate of the reaction between Co(II), Ni(II) and Cu(II) ions with 1-(2-pyridylazo)2-naphthol in a pH 5.8 buffer solution and in micellar media at 25°C. The absorption kinetic profiles of the solutions were monitored by measuring the absorbance at 570 nm at 2 s intervals during the time range of 0–10 min after initiation of the reaction. The experimental calibration matrix for the partial least squares (PLS-1) model was designed with 30 samples. The cross-validation method was used for selecting the number of factors. The results showed that simultaneous determination could be performed in the range 0.1-2 μg mL⁻¹ for each cation. The proposed method was successfully applied to the simultaneous determination of Cu(II), Ni(II) and Co(II) ions in water and in synthetic alloy samples.      

Emulsion liquid membrane extraction of Ni(II) and Co(II) from acidic chloride solutions using bis-(2-ethylhexyl) phosphoric acid as extractant

An emulsion liquid membrane process using bis-(2-ethylhexyl) phosphoric acid (D2EHPA) to extract and separate Ni(II) and Co(II) from acidic chloride solutions is described. Liquid membrane consists of a diluent, a surfactant (Span 80), and an extractant (D2EHPA). Hydrochloric acid was used as the stripping solution. The important parameters governing the permeation of nickel and their effect on the separation process have been studied. These parameters are stirring speed, feed phase pH, surfactant concentration, extractant concentration, stripping phase concentration, phase ratio, initial concentration of metal, and treatment ratio. The optimum conditions have been determined. The separation factors of Ni(II) with respect to Co(II), based on initial feed concentration, have been experimentally determined. Furthermore, the extraction selectivity for Co(II) over Ni(II) has been improved by using D2EHPA during the initial minutes.     

Novel flame retardant paint based on Co(II) and Ni(II) metal complexes as new additives for surface coating applications

The study is focused on the synthesis of a new Co(II) and Ni(II) metal complexes, which is synthesized by the reaction of the isatin 4‐aminoantipyrine Schiff base ligand with selected divalent Co(II) and Ni(II) ions and their possible applications as flame retardant additives in paint formulations for surface coating application. The prepared metal complexes were characterized using a combination of Fourier transform infrared, elemental analysis, proton nuclear magnetic resonance, ¹³C‐NMR spectra, and mass spectroscopy. The prepared Schiff base ligand metal complexes were physically added to alkyd paint formulation to give coating formulations at a laboratory scale and then applied onto plywood and steel panels using a brush. The ignitability and oxygen index values obtained indicated that the paint which contained the prepared Co(II) and Ni(II) metal complexes as additives exhibited very good flame retardant. The physical and mechanical characteristics of the coatings were studied in order to estimate any disadvantages due to the incorporation of the additives. It was discovered that the added substances did not impact the hardness, flexibility, and adhesion of the prepared coating films. The gloss of the paint formulation film was improved due to the incorporation of the aromatic ring into the formulation and the level of the oil percent.     

Synthesis and structural studies of Co(II), Ni(II) and Cd(II) complexes with 2-acetylpyridine

Three new mononuclear complexes [Co(2-Acpy)₂(H₂O)₂](NO₃)₂ (1), [Ni(2-Acpy)₂(H₂O)₂](NO₃)₂ (2) and [Cd(2-Acpy)₂(NO₃)₂] (3) (2-Acpy = 2-acetylpyridine) have been synthesized and characterized by elemental analysis, IR and UV–Vis spectroscopy. The structures of 1 and 3 were accomplished by single crystal X-ray diffraction. Crystallographic investigation of 1 reveals monomeric, dicationic units in which the cobalt(II) ion is six-coordinate. The coordination sphere is formed by two N, O bidentate acetylpyridine ligands and two water molecules. The crystal structure of 3 consists of monomeric units in which the cadmium is eight-coordinate. Both the organic ligand and nitrate groups are bidentate chelators. The supramolecular solid-state architecture is sustained by π–π interactions.     

Synthesis,spectroscopic, and thermal analyses of trinuclear Mn(II), Co(II), Ni(II), and Zn(II) complexes with some sulfa derivatives

New bi- and trihomonuclear Mn(II), Co(II), Ni(II), and Zn(II) complexes with sulfa-guanidine Schiff bases have been synthesized for potential chemotherapeutic use. The complexes are characterized using elemental and thermal (TGA) analyses, mass spectra (MS), molar conductance, IR, ¹H-NMR, UV-Vis, and electron spin resonance (ESR) spectra as well as magnetic moment measurements. The low molar conductance values denote non-electrolytes. The thermal behavior of these chelates shows that the hydrated complexes lose water of hydration in the first step followed by loss of coordinated water followed immediately by decomposition of the anions and ligands in subsequent steps. IR and ¹H-NMR data reveal that ligands are coordinated to the metal ions by two or three bidentate centers via the enol form of the carbonyl C=O group, enolic sulfonamide S(O)OH, and the nitrogen of azomethine. The UV-Vis and ESR spectra as well as magnetic moment data reveal that formation of octahedral [Mn₂L¹(AcO)₂(H₂O)₆] (1), [Co₂(L¹)₂(H₂O)₈] (2), [Ni₂L¹(AcO)₂(H₂O)₆] (3), [Mn₃L²(AcO)₃(H₂O)₉] (5), [Co₃L²(AcO)₃(H₂O)₉] · 4H₂O (6), [Ni₃L²(AcO)₃(H₂O)₉] · 7H₂O (7), [Mn₃L³(AcO)₃(H₂O)₆] (9), [Co₂(HL³)₂(H₂O)₈] · 4H₂O (10), [Ni₃L³(AcO)₃(H₂O)₉] (11), [Mn₃L⁴(AcO)₃(H₂O)₉] · H₂O (13), [Co₂(HL⁴)₂(H₂O)₈] · 5H₂O (14), and [Ni₃L⁴(AcO)₃(H₂O)₉] (15) while [Zn₂L¹(AcO)₂(H₂O)₂] (4), [Zn₃L²(AcO)₃(H₂O)₃] · 2H₂O (8), [Zn₃L³(AcO)₃(H₂O)₃] · 3H₂O (12), and [Zn₃L⁴(AcO)₃(H₂O)₃] · 2H₂O (16) are tetrahedral. The electron spray ionization (ESI) MS of the complexes showed isotope ion peaks of [M]⁺ and fragments supporting the formulation.     

Synthesis and characterization of a new pyrrolidine containing sulfur ligand and the transition metal complexes of Co(II), Ni(II) and Cu(I)

Potassium 1,3-dipyrrolidinopropan-2-O-xanthate (LK), and its complexes with Co(II), Ni(II) and Cu(I) have been prepared and characterized as [CoL₂(H₂O)₂]?·?2H₂O, [NiL₂(H₂O)₂] and CuL?·?2H₂O by FT-IR, ¹H and ¹³C NMR spectroscopies, elemental analyses, magnetic susceptibility and TGA techniques.     

Synthesis and characterization of Co(II), Ni(II), Zn(II) and Cu(II) complexes with a new tetraazamacrocyclic Schiff base ligand containing a piperazine moiety: X-ray crystal structure determination of the Co(II) complex

Two macrocyclic Schiff base ligands, L¹ [1+1] and L² [2+2], have been obtained in a one-pot cyclocondensation of 1,4-bis(2-formylphenyl)piperazine and 1,3-diaminopropane. Unfortunately, because of the low solubility of both ligands, their separation was unsuccessful. In the direct reaction of these mixed ligands (L¹ and L²) and the appropriate metal ions only [CoL¹(NO₃)]ClO₄, [NiL¹](ClO₄)₂, [CuL¹](ClO₄)₂ and [ZnL¹(NO₃)]ClO₄ complexes have been isolated. All the complexes were characterized by elemental analyses, IR, FAB-MS, conductivity measurements and in the case of the [ZnL¹(NO₃)]ClO₄ complex with NMR spectroscopy.     

Complexation of N-bis[2-(1,2-dicarboxyethoxy)ethyl]aspartic acid with Fe(II), Co(II), and Ni(II) in aqueous solution

In a search for environment-friendly metal chelating ligands for industrial applications, the protonation and complex formation equilibria of N-bis[2-(1,2-dicarboxyethoxy)ethyl]aspartic acid (BCA6) with Fe(II), Co(II), and Ni(II) ions in aqueous 0.1 M NaCl solution were studied at 25°C by potentiometric titration. The model for complexation and the stability constants of different complexes were determined for each metal ion using SUPERQUAD. In all cases, complex formation was dominated by stable ML^4? complexes.     

Synthesis,characterization and antimicrobial activity of pentagonal-bipyramidal isothiocyanato Co(II) and Ni(II) complexes with 2,6-diacetylpyridine bis(trimethylammoniumacetohydrazone)

Pentagonal-bipyramidal isothiocyanato Co(II) and Ni(II) complexes with condensation product of 2,6-diacetylpyridine and trimethylammoniumacetohydrazide (Girard’s T reagent) were synthesized and characterized by elemental analyses, IR and UV–vis spectra, molar conductivity, and magnetic susceptibility. Crystal structures of the Co(II) and Ni(II) complexes were also determined. Antimicrobial activities of the ligand and metal complexes were examined.     

Thermal, spectral and magnetic characterization of Co(II), Ni(II) AND Cu(II) 4-chloro-2-nitrobenzoates

Physico-chemical properties of 4-chloro-2-nitrobenzoates of Co(II), Ni(II), and Cu(II) were studied. The complexes were obtained as mono- and trihydrates with a metal ion to ligand ratio of 1:2. All analysed 4-chloro-2-nitrobenzoates are polycrystalline compounds with colours depending on the central ions: pink for Co(II), green for Ni(II), and blue for Cu(II) complexes. Their thermal decomposition was studied only in the range of 293–523 K, because it was found that on heating in air above 523 K 4-chloro-2-nitrobenzoates decompose explosively. Hydrated complexes lose crystallization water molecules in one step and anhydrous compounds are formed. The final products of their decomposition are the oxides of the respective transition metals. From the results it appears that during dehydration process no transformation of nitro group to nitrite takes place. The solubilities of analysed complexes in water at 293 K are of the order of 10^–4–10^–2 mol dm^–3. The magnetic moment values of Co²⁺, Ni²⁺ and Cu²⁺ ions in 4-chloro-2-nitrobenzoates experimentally determined at 76–303 K change from 3.89 to 4.82 μ_B for Co(II) complex, from 2.25 to 2.98 μ_B for Ni(II) 4-chloro-2-nitrobenzoate, and from 0.27 to 1.44 μ_B for Cu(II) complex. 4-chloro-2-nitrobenzoates of Co(II), and Ni(II) follow the Curie–Weiss law. Complex of Cu(II) forms dimer.     

Spectral and thermal studies of new Co(II) and Ni(II) hexaaza and octaaza macrocyclic complexes

The macrocyclic complexes of Co(II) and Ni(II) having chloride or thiocyanate ions in the axial position have been synthesized and characterized. These complexes are synthesised by the template condensation of o-phenylenediamine or 2,3-butanedionedihydrazone with the appropriate aldehydes in NH₄OH solution in the presence of the metal ions, Co(II) and Ni(II). The complexes were characterized by spectroscopic methods (IR, UV-Vis and ESR) and magnetic measurements as well as thermal analysis (TG and DTA). The results obtained are commensurate with the proposed formulae. Spectral studies indicate that these complexes have an octahedral structure. From conductivity measurements the complexes are non-electrolytes. The kinetic of the thermal decomposition of the complexes was studied and the thermodynamic parameters are reported.     

Synthesis and characterization of Cu(II), Co(II) and Ni(II) coordination polymers containing bis(imidazolyl) ligands

Two structurally related flexible imidazolyl ligands, bis(N-imidazolyl)methane (L₁) and 1,4-bis(N-imidazolyl)butane (L₂), were reacted with Cu(II), Co(II) and Ni(II) salts of aliphatic/aromatic dicarboxylic acids resulting in the formation of a number of novel metal–organic coordination architectures, [CuB₂(ox)₂(L₁)₂(H₂O)₂] · 4H₂O (1) (ox = oxalate), [Cu(pdc)(L₂)_1.5] · 4H₂O (2, pdc = pyridine-2,6-dicarboxylate), [Co(L)₂(H₂O)₂](tp) · 4H₂O (3, tp = terephthalate), [Ni(L₁)₂(H₂O)₂](ip) · 5H₂O (4, ip = isophthalate), [Cu₂(L₁)₄(H₂O)₄](tp)₂ · 7H₂O (5), [Co(mal)(L₁)(H₂O)] · 0.5MeOH (6, mal = malonate), [Co(pdc)(L₁)(H₂O)] (7). All the complexes have been structurally characterized by X-ray diffraction analysis. The different coordination modes of the dicarboxylate anions, due to their chain length, rigidity and diimidazolyl functionality, lead to a wide range of different coordination structures. The coordination polymers exhibit 1D single chain, ladder, 2D sheet and 2D network structures. The aliphatic and aromatic dicarboxylates can adopt chelating μ₂ and chelating-bridging μ₃ coordination modes, or act as uncoordinated counter anions. The central metal ions are coordinated in N₂O₄, N₄O₂, N₂O₃ and N₃O₃ fashions, depending on the ancillary ligands. The topology of 1 gives rise to macrocycles which are connected through hydrogen bonds to form 1D chains, whereas compound 2 exhibits a 1D polymeric ladder in which the carboxylate acts as a pincer ligand. Compounds 3–5 show doubly bridged 1D chains, and the dicarboxylate groups are not coordinated but form 2D corrugated sheets with water molecules intercalated between the cationic layers. Compound 6 has a 2D network sheet structure in which each metal ion links three neighboring Co atoms by the bis(N-imidazolyl)methane ligand. The cobalt compound 7, with a 2D polymeric double sheet structure, is built from pincer carboxylate (pdc) and 1,4-bis(N-imidazolyl)methane ligands.