Extraction of cobalt by the AOT microemulsion system

The extraction of cobalt by Winsor II microemulsion system was studied. In the bis (2-ethylhexyl) sulfosuccinate sodium salt (AOT)/n-pentanol/n-heptane/NaCl system, AOT was used as a anionic surfactant to form microemulsion in n-heptane, n-pentanol was injected in the microemulsion as a cosurfactant. Co(II) was found to be extracted into the microemulsion phase due to ion pair formation such as Co²⁺(R–SO₃ ⁻)Cl. The influence of different parameters such as the volume ratio of aqueous phase to microemulsion, surfactant concentration, pH of the feed solutions, cosurfactant concentration as well as temperature on the extraction yield (E%) were investigated. The results showed that it was possible to extract 95% of cobalt by the AOT Winsor II microemulsion.     

Radiation polymerization of methacrylates controlled by a chain transfer catalyst

The effect of γ-radiation dose and chain transfer catalyst on polymerization of methyl methacrylate (MMA) and copolymerization of MMA with hydroxyethyl methacrylate or triethylene glycol dimethacrylate has been investigated. The addition of 5 × 10^?4?10^?3 mol/L of bis[(difluoroboryl) isopropylpyridine dimethylglyoximato]cobalt(II) (Co(II)) makes it possible to produce macromonomers MM _n ⁼⁼ bearing terminal double bonds and having a degree polymerization of n = 2?40 and a polydispersity index of 1.05?1.15. It has been found that the degree polymerization of the macromonomers increases with the increasing γ-radiation dose and monomer conversion through the mechanism of the reversible β-cleavage of the terminal unit: R _k ^? + MM _n ⁼ ? MM _k+1 ⁼ + R _n-1 ^? followed by the living polymerization of both radicals. This reaction may compete with the catalytic chain transfer reaction and have a significant effect on the evolution of the molecular weight characteristics of the macromonomers during the course of MMA (co)polymerization.     

Coordination polymer 4,4,10,10-tetramethyl-1,3,7,9-tetraazaspiro[5.5]undecane-2,8-dione with cobalt(II) nitrate: Synthesis and molecular structure

The coordination polymer of cobalt(II) nitrate with bicyclic bis(urea), 4,4,10,10-tetramethyl-1,3,7,9-tetraazaspiro[5.5]undecane-2,8-dione (Sk) {[Co(C₁₁H₂₀N₄O₂)₂(H₂O), Co(C₁₁H₂₀N₄O₂)₂(H₂O)₂]⁴⁺(NO ₃ ^- )₄} _n (I), is synthesized for the first time, and its atomic structure is determined (CIF file CCDC no. 925792). The crystals of compound I are monoclinic: space group P2/c, a = 26.1284(6), b = 7.1763(2), c = 17.1825(5) Å, β = 105.042(3)°, V = 3111.43(15) ų, ρ_calcd = 1.474 g/cm³, Z = 2. The powder X-ray pattern at 293 K is refined using the Rietveld method to confirm the single-phase character of the obtained sample of powdered compound I: a = 26.1456(9), b = 7.1810(4), c = 17.1997(11) Å, β = 105.016(3)°, V = 3119.0(3) ų. The content of the major phase of compound I in the sample is 100 ± 1%, and impurity phases are absent. The crystal of compound I contains two types of chains oriented along the crystallographic direction [001] with similar structures but differed in the coordination numbers of the cobalt atoms. The Co(1) atom has a coordination number of 5 (trigonal bipyramid), and the coordination number of the Co(2) atom is 6 (octahedron). The nitrate anions are uncoordinated.     

Polycatenate Structure and Thermal Analysis of a New 2D + 2D Cobalt(II) Coordination Polymer Based on 5-Methoxylisophthalic Acid and 3,5-Bis(imidazole-1-yl)pyridine Co-Ligands

A new Co(II) compound, namely [Co(CH₃O-H₂Ip)(Bip)] _n (I) (CH₃O-H₂Ip = 5-methoxylisophthalic acid and Bip = 3,5-bis(imidazole-1-yl)pyridine), has been synthesized through combination of CH₃O-H₂Ip, Bip and Co(II) acetate under hydrothermal condition and structurally characterized by IR spectroscopy, elemental analysis and single-crystal X-ray diffraction (CIF file CCDC no. 977220). It crystallizes in triclinic, space group P1? with a = 9.764(6), b = 10.106(6), c = 11.673(7) Å, α = 104.12970°, β = 100.601(7)°, γ = 105.324(7)°, V = 1038.6(11) ų, C₂₀H₁₆CoN₅O₅, Mr = 465.31, Z = 2, ρ_calcd = 1.488 g/cm³, μ(MoK_α) = 0.869 mm^?1, F(000) = 476, the final R = 0.0652 and wR = 0.1530. The X-ray analysis demonstrates that compound I exhibits a 2D + 2D polyrotaxane (4, 4) net network. Moreover, the thermal analysis of compound I has also been investigated.     

Molecular dynamics simulations of the characteristics of sodium carboxymethyl cellulose with different degrees of substitution in a salt solution

Sodium carboxymethyl cellulose (SCMC) with different degrees of substitution (DS) possesses structural characteristics and physicochemical properties that are important in broad areas of industrial applications. This reported work investigated the structural characteristics, including the effective length (L _ef), the radius of gyration (R _g), and the hydrodynamic radius (R _H), and the physicochemical properties, including intrinsic viscosity ([η]) and salt tolerance, of SCMC with a DS more than 1.0 in NaCl solution using molecular dynamics (MD) simulations. In the MD simulations, the DS of SCMC varied from 1.2 to 2.8, and the NaCl concentration varied from 0 to 1.4 mol/L. MD simulation results showed that with the increment of NaCl concentration, the L _ef (or R _g or R _H) of SCMC decreased; with the increment of the DS, the L _ef of SCMC increased. Also, the variation tendency of [η] in the NaCl solution was consistent with its L _ef (or R _g or R _H). It was noted that the salt tolerance (represented by D) of SCMC increased as the DS increased. In addition, the sharp variation of the D value of SCMC occurred in the range of DS of 1.6 to 2.0, which agreed with the reported experimental results. Radial distribution function analyses showed that the Na⁺ cations had a stronger interaction with the carboxyl groups in SCMC with lower DS when it was present in a salt solution of higher concentration, which also reasonably explained the variation of L _ef, R _g, R _H, [η], and D of SCMC in NaCl solution.     

Coordination properties of N-(Thio)phosphorylated thioureas and thioamides with respect to Co(II), Ni(II), Zn(II), and Cd(II) ions in solution

The acid-base and coordination properties of N-(thio)phosphorylated thioureas and thioamides R¹C(X)NHP(Y)R ₂ ² , where X, Y = S, O (in various combinations); R¹ = t?Bu, i-Pr, PhNH, Ph; R² = (OPr?i), with respect to Co(II), Ni(II), Zn(II), and Cd(II) ions have been studied by pH-metry and UV spectrometry in an organic solvent. The pK values, the stability constants logβ and the maximum accumulated fractions of complex species in the solution have been calculated.     

Synthesis and characterization of tribenzyltin(IV) and dibenzyltin(IV) complexes of 2-{[(2Z)-3-hydroxy-1-methyl- 2-butenylidene]amino}acetic acid: Crystal structure of tribenzyl{2-{[(2Z)-3-hydroxy-1-methyl-2-butenylidene] amino}acetato}tin(IV)

Reactions of equimolar quantities of potassium 2-{[(2Z)-3-hydroxy-1-methyl-2-butenylidene]amino}acetate, with R _n SnX_4?n (R: benzyl– and n=2 or 3) in methanol yielded products of compositions LHSn(PhCH₂)₃ and LSn(PhCH₂)₂, respectively. The complexes were characterized by microanalysis, IR, NMR (¹H, ¹³C, ¹¹⁹Sn) and ^119mSn Mössbauer spectroscopy. A full characterization of the structure of the complex, tribenzyl{2-{[(2Z)-3-hydroxy-1-methyl-2-butenylidene]amino}acetato}tin(IV), was carried out by single crystal X-ray crystallography. The compound exists as centrosymmetric dimers in which two ligand molecules bridge the two tin centres. Each of the tin atoms in the dimeric unit is five coordinate in an approximately trigonal bipyramidal configuration, with carbon atoms in the equatorial positions and oxygen atoms arranged axially.     

Mononuclear cobalt (III) complexes with <Emphasis Type="Italic">N</Emphasis>-salicylidene-2-hydroxy-5-bromobenzylamine and <Emphasis Type="Italic">N</Emphasis>-salicylidene-2-hydroxy-5-chlorobenzylamine

Cobalt (III) complexes with N-salicylidene-2-hydroxy-5-bromobenzylamine (H₂sbba) and N-salicylidene-2-hydroxy-5-chlorobenzylamine (H₂scba), [n-(C₄H₉)₄N][Co(sbba)₂] (I) and [n-(C₄H₉)₄N][Co(scba)₂] (II), were synthesized. The crystal structure of II was determined by the single-crystal X-ray diffraction method at 90 K confirming its crystallization in the monoclinic space group P2₁/n with a = 11.729(2) Å, b = 16.901(3) Å, c = 21.483(4) Å, β = 98.840(4)°, V = 4208.2(14) ų, D_x = 1.295 g cm^?3, and Z = 4. The R1 [I > 2σ(I)] and wR2 (all data) values of 0.0664 and 0.1920, respectively, for all 9521 independent reflections. The compound is composed of a tetra(n-butyl)ammonium cation and an octahedral cobalt(III) complex anion with two scba^2? ligands in a meridional fashion. The electronic spectral features of I and II are consistent with the octahedral cobalt(III) ion with an N₂O₄ donor set.     

Synthesis,characterization, spectroscopic and catalytic oxidation studies of Fe(III), Ni(II), Co(III), V(IV) and U(VI) Schiff base complexes with N,O donor ligands derived from 2,3-diaminopyridine

Fifteen new complexes of transition metals were designed using three Schiff base ligands and aldol condensation of 2,3-diaminopyridine with 5-R-2-hydroxybenzaldehyde (R = F, Cl, Br) in the 1:2 molar ratio. The tetradentate ligands N,N′-bis(5-R-2-hydroxybenzaldehyde) pyridine were acquired with the common formula H₂[(5-R-sal)₂py] and characterized by IR, UV–Vis spectra, ¹H-NMR and elemental analysis. These ligands produce 1:1 complexes M[(5-R-sal)₂py] with Fe(III), Ni(II), Co(III), V(IV) and U(VI) metal ions. The electronic property and nature of complexes were identified by IR, UV–Vis spectra, elemental analysis, X-ray crystallography and cyclic voltammetric methods. The catalytic activity of complexes for epoxidation of styrene with UHP as primary oxidant at minimal temperature (10 °C) has been planned. The spectral data of the ligands and their complexes are deliberate in connection with the structural changes which happen due to complex preparation. The electrochemical outcome has good conformability with what suggested for electronic interaction among metal center and ligand by the UV–Vis and IR measurements.     

Crystal structure of potassium dysprosium octacyanotungstate(IV) heptahydrate

The crystal structure of KDyW(CN)₈ · 7H₂O was determined by X-ray diffraction. The crystals are triclinic, space group PI, a = 7.6284(7) Å, b = 9.2435(9) Å, c = 14.4778(14) Å, α = 80.673(11)°, β = 87.561(11)°, γ = 77.603(11)°, V = 983.86(16) ų, Z = 2, ρ_calcd = 2.429 g/cm³, R = 0.0249, w _R = 0.0502 for 3601 independent reflections. The coordination polyhedron of tungsten is a highly deformed tetragonal antiprism [W(CN)₈], that of dysprosium is a tetragonal antiprism [DyN₄(H₂O)₄]. Some cyano groups are bridging being coordinated to tungsten and dysprosium by C and N atoms, respectively, and form a 3D structure via potassium atoms. The coordination polymer can be described as {[K(H₂O)][Dy(H₂O)₄][W(CN)₈]}n· 2nH₂O.     

Equilibrium and kinetics of calcium–uranyl–carbonate adsorption on silica nanoparticles

Solvent extraction studies on the purification of uranium from zirconium rich sodium diuranate (SDU) feed was carried out using n-tri butyl phosphate (TBP) as extractant and n-decanol as phase modifier. The presence of Zr in SDU leached solution leads to the formation of third phase during liquid–liquid extraction of uranium which was successfully prevented by addition of n-decanol in 30% (v/v) TBP/n-dodecane mixture. A seven stage counter current extraction of SDU feed solution followed by five stage stripping were carried out using optimum concentration of phase modifier 15% n-decanol-30% TBP in n-dodecane as solvent. Based on the findings a process flow-sheet has been developed for the purification of SDU to nuclear grade ammonium diuranate.     

Synthesis,crystal structure of new linear trinuclear isovalence Co(II)([Co<Subscript>3</Subscript>(H–L)<Subscript>2</Subscript>(L)<Subscript>2</Subscript>]), and visualizing intermolecular interactions with Hirshfeld surface method

S-allyl-β-N-[(2-hydroxyphenyl)methylene]hyrazinecarbodithioate) (1, H₂L), the Schiff base of dithiocarbazate with unsaturated allyl substitution, can act as a new tridentate SNO ligand H₂–L and react with cobalt(II) nitrate hexahydrate to form the novel linear trinuclear isovalence Co(II) complex, [Co₃(H–L)₂(L)₂] 2C₂H₅OH (2). The compounds were characterized by elemental analysis, infrared, and ultraviolet spectroscopy. Compound 2 was also characterized by single-crystal X-ray analysis and crystallizes in the orthorhombic space group, Pbcn, with a = 30.643(1) Å, b = 9.118(4) Å, c = 19.017(7) Å, α = β = γ = 90°, V = 5312.95 Å³, Z = 4, and R ₁ = 0.0790, (wR ₂) = 0.1223. The six-coordinate central Co(II) atom is bonded to two deprotonated metal-containing ligands. The terminal Co(II) atoms are in a square planar SNON four-coordinate environment and connected to the central Co(II) by N-atoms from the ligand backbone. For quantifying the intermolecular interactions in crystal lattice, the new d _norm surface and the breakdown of fingerprint plots have been used for visualizing and exploring the compound 2.     

Syntheses,Structures, and Magnetic Properties of Two Mn(II) Coordination Polymers Based on 4-Fluorocinnamic Acid and 1,10-Phenanthroline

Two Mn(II) coordination polymers, {[Mn₃ (Pfca)₆(Phen)₂] · 2DMF} _n (I) and [Mn(Pfca)₂(Phen)(H₂O)] _n (II) (HPfca = 4-fluorocinnamic acid, Phen = 1,10-phenanthroline), were synthesized and characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, and singlecrystal X-ray diffraction (CIF files CCDC nos. 967513 (I), 1542972 (II)). Complex I crystallizes in the triclinic crystal system, space group Pī with a = 11.0821(11), b = 12.2632(12), c = 15.0288(15) Å, α = 87.3760(10)°, β = 88.4610(10)°, γ = 81.2220(10)°, V = 2016.0(3) Å3, ρ_c = 1.369 g/cm³, M _r = 1662.25, Z = 1, F(000) = 853, μ = 0.543 mm^–1, the final R = 0.0592 and wR = 0.1681 for 15498 observed reflections with I > 2σ(I). Complex II is of monoclinic system, space group P2₁/c with a = 18.0539(19), b = 8.5806(9), c = 18.758(2) Å, β = 116.5700(10)°, V = 2599.0(5) ų, ρ_c = 1.491 g/cm³, M _r = 583.44, Z = 4, F(000) = 1196, μ = 0.567 mm^–1, the final R = 0.0337 and wR = 0.0853 for 18139 observed reflections with I > 2σ(I). Complex I features linear Mn(II)-trinuclear units, which form 1D chain structure through F···F weak interactions, and complex II is 1D polymeric Mn(II)-chains. Antiferromagnetic coupling interactions exist within Mn(II)- carboxylate trinuclear in I (J =–0.40 cm^–1) and Mn(II)-carboxylate chain in II (J =–0.45 cm^–1).     

Complexing and extraction of palladium(II) by <Emphasis Type="Italic">n</Emphasis>-alkyl(tolyl)thiamethylcalix[4]arenes from chloride solutions

Complexing [PdCl₄]^2? with calix[4]arenes (L) functionalized by CH₂SR (R = Me (1), n-Bu (2), or p-Tol (3)) in their upper rims has been studied in toluene and CCl₄. The stoichiometry of the extracted palladium species (PdCl₂) _n L, where n = 1 or 2 is established by spectroscopic methods (NMR spectroscopy, UV/Vis spectrophotometry, atomic absorption) and extraction. For slow coordinative extraction, the concentration constants of complex formation and extraction from chloride solutions are determined using the coupled equilibria method. The kinetic and thermodynamic laws of extraction coincide, and their parameters increase in the following row of the substituents at the sulfur atom: p-Tol < Bu < Me.     

Synthesis and crystal and molecular structure of the [Co(HL)Cl<Subscript>2</Subscript>] complex (H<Subscript>2</Subscript>L is an optically active terpene bis-pinane propylenediaminodioxime)

Interaction of Co(II) chloride with optically active bis-pinane propylenediaminodioxime (H₂L) gave a diamagnetic compound of Co(III) with a composition [Co(HL)Cl₂]. The crystal and molecular structure of the compound was determined by X-ray diffraction (XRD) analysis (Enraf-Nonius CAD-4 diffractometer, λMoK_α, 703 F _hkl , R = 0.0347). The crystals are orthorhombic with unit cell parameters a = 8.989(1) Å, b = 12.351(2) Å, c = 22.425(3) Å, V = 2487.7(6) ų, Z = 4, ρ_calc = 1.420 g/cm³, space group P2₁2₁2₁. The crystal structure of the complex is composed of discrete one-center molecules. In the complex, the Co³⁺ ion coordinates four N atoms of the tetradentate cycle-forming ligand (HL^? anion) and two Cl atoms. The coordination polyhedron of Co is a distorted octahedron Cl₂N₄.     

Synthesis and characterization of half-sandwich ruthenium(II) complexes with N-alkyl pyridyl-imine ligands and their application in transfer hydrogenation of ketones

A series of new arene ruthenium(II) complexes were prepared by reaction of ruthenium(II) precursors of the general formula [(η⁶-arene)Ru(μ-Cl)Cl]₂ with N,N′-bidentate pyridyl-imine ligands to form complexes of the type [(η⁶-arene)RuCl(C₅H₄N-2-CH=N-R)]PF₆, with arene = C₆H₆, R = iso-propyl (1a), tert-butyl (1b), cyclohexyl (1c), cyclopentyl (1d) and n-butyl (1e); arene = p-cymene, R = iso-propyl (2a), tert-butyl (2b). The complexes were fully characterized by ¹H NMR and ¹³C NMR, UV–Vis and IR spectroscopies, elemental analyses, and the single-crystal X-ray structures of 2a and 2b have been determined. The single-crystal molecular structure revealed both compounds with a pseudo-octahedral geometry around the Ru(II) center, normally referred to as a piano stool conformation, with the pyridyl-imine as a bidentate N,N ligand. The activity of all complexes in the transfer hydrogenation of cyclohexanone in the presence of NaOH and iso-propanol is reported, the compounds showing turnover numbers of close to 1990 and high conversions. Complex 2b was also shown to be very effective for a range of aliphatic and cyclic ketones, giving conversions of up to 100 %.     

Chemometrics-Assisted Optimization of Beta-/Gamma-Tocol Separation on a C<Subscript>30</Subscript> Stationary Phase in Reversed-Phase LC

This paper presents a chemometrics-assisted optimization study to improve the separation of tocopherol (-T) and tocotrienol (-TT) homologues on a C₃₀ stationary phase in reversed-phase HPLC. The HPLC settings were optimized using a central composite design and the response surface methodology. Flow rate, column temperature, and mobile phase composition were chosen as independent variables. Peak resolution (R_s), analysis time (t_R), and peak symmetries of the tocopherol isomers were chosen as response variables. Optimum performance in terms of R_s was obtained at a flow rate of 0.31 mL min^?1, a temperature of 8.70 °C, and % B content (methyl tert-butyl ether: methanol: water, 80:18:2, v/v/v) in the mobile phase of 38.12%. The analysis of variance and regression analysis gave adjusted R² values of 0.9841 for R_s, 0.9850 for t_R-(α-T), 0.9853 for t_R-(β-T), and 0.9204 for the peak symmetry of β-T. This confirms the good agreement of experimental data with predicted values. The close eluting peaks of β-/γ-tocol could be baseline separated at the optimized conditions at a minimized analysis time. Empirical second-order polynomial models were derived that gave statistically high significances (P?<?0.0001). Hence, the models can be successfully employed to predict the optimum separation conditions of co-eluting peaks of β-/γ-tocols. The optimized method was successfully applied to determine the individual tocol homologues in various cold pressed edible oils. Total contents ranged from 15 to almost 2600 mg tocol kg^?1 oil.     

Electron affinity and substituent effects in radical anions

The first vertical electron affinities EA of 13 series of molecules and free radicals D(X _i ) _n are related to the inductive (σ _I ), resonance (σ _R ^? ), and polarization (σ_α) parameters of substituents X _i by the dependences EA = EA _H + aΣσ _I + bΣσ _R/? + cΣσ_α: In radical anions D^+·(X _i ) _n , compared to radical cations D^+·(X _i ) _n , the polarization interaction is weaker or similar in magnitude but has an opposite sign. The previously unknown resonance parameters σ _R ^? of substituents SiMe₃ and CH₂SiMe₃ bound to the radical anion center H₂C=CH^?· were calculated.     

Geometries,stabilities, electronic and magnetic properties of small aluminum cluster anions doped with cobalt: A density functional theory study

The geometrical structures, relative electronic and magnetic properties of small Al_nCo^– (1 ≤ n ≤ 9) clusters are systematically investigated within the framework of density functional theory at the BPW91 level. The single Co doping can dramatically affect the ground state geometries of the 1 Al_n+1^- clusters. At the same time, the resulting geometries show that the lowest energy Al_nCo^– clusters prefer to be three dimensional structures. Here, the relative stabilities are investigated in terms of the calculated average binding energies, fragmentation energies, and second-order energy differences. Moreover, the result of the highest occupiedlowest unoccupied molecular orbital energy gaps indicates that Al₆Co^– clusters have the highest chemical stability for Al_nCo^– (1 ≤ n ≤ 9) clusters. Furthermore, the natural population analysis reveals that the charges in Al_nCo^– clusters transfer from the Al frames to the Co atom. Additionally, the analyses of the local and total magnetic moments of the Al_nCo^– clusters show that the magnetic effect mainly comes from the Co atom.     

Syntheses,characterization, and crystal structures of two dinuclear nickel(II) and copper(II) complexes with Schiff bases

The phenolic azide bridged dinuclear nickel(II) complex, [Ni₂(L¹)₂(N₃)(H₂O)(μ_1,1-N₃)] · EtOH (I), and the thiocyanate bridged dinuclear copper(II) complex, [Cu₂(L²)₂(μ_1,1-NCS)₂] (II), where L¹ and L² are the deprotonated forms of 2-mothoxy-6-[(2-piperidin-1-ylethylimino)methyl]phenol and 2,4-dichloro-6-[(2-methylaminoethylimino)methyl]phenol, respectively, were synthesized and characterized by elemental analysis, IR spectra, and single-crystal X-ray diffraction. The crystal of I is orthorhombic: space group Pbca, a = 12.172(1), b = 20.953(1), c = 29.779(2) Å, V = 7594.8(9) ų, Z = 8. The crystal of II is monoclinic: space group P2₁/n, a = 8.7615(11), b = 19.672(2), c = 16.568(2) Å, β = 99.449(2)°, V = 2816.9(6) ų, Z = 4. The Ni atoms in I are in octahedral coordinations, and the Cu atoms in II are in square-pyramidal coordinations.