Preparation and Thermal Decomposition of Copper(II) Complexes with 4-Methylimidazole

Simple and mixed compounds of the formulae Cu(4-Meim)₂, CuSal(4-Meim), CuSal(4-Meim)₂ and CuSalox(4-Meim)₂, where 4-Meim=4-methylimidazole, Sal=(OC₆H₄COO)²⁻, Salox=(OC₆H₄CHNO)²⁻ have been prepared. Thermal decomposition reactions have been established on the basis of thermal and X-ray analyses of these compounds. The pyrolysis proceeds in several (3–4) stages connected with the mass loss and exothermic effects. As a result of the last stage of decomposition CuO is formed. This revised version was published online in August 2006 with corrections to the Cover Date.     

Structure of Iron(III)-containing complexes based on the azomethine — 4,4′-dodecyloxy-benzoyloxybenzoyl-4-salicylidene-<Emphasis Type="Italic">N</Emphasis>′-Ethyl-<Emphasis Type="Italic">N</Emphasis>-ethylenediamine molecule

Iron(III)-containing complexes with an asymmetric tridentate azomethine 4,4′-dodecyloxybenzoyloxybenzoyl-4-salicylidene-N′-ethyl-N-ethylenediamine ligand with NO₃⁻, PF₆⁻, Cl⁻, and BF₄⁻ counterions are synthesized. The presence of the complexation ion is confirmed by the far FTIR spectra. The structure of the compounds is determined by the matrix-assisted laser desorption/ionizationtime of flight (MALDI-ToF) method. The results of mass-spectrometric studies are consistent with the elemental analysis data. The complexation of iron salts with the asymmetric tridentate ligand is found to yield compounds of the 1:1 composition with octahedral packing of iron in the complex.     

Homo- and heteronuclear complexes of a new,vicinal dioxime ligand

A new symmetrical vicinal dioxime, N,N′-bis-{4-[[(2-hydroxyphenyl)methylene]hydrazinecarbonyl]phenyl}diaminoglyoxime (LH₄), was prepared by reacting anti-dichloroglyoxime with salicylaldehyde 4-aminobenzoylhydrazone. The reaction of ligand with Ni²⁺ salts gave mono-and homopentanuclear complexes, [Ni(LH₃)₂] and [Ni₅(LH)₂X₂]. Furthermore, heteropentanuclear complexes of dioxime ligand, [Cu₄Ni(LH)₂X₄], were prepared by the reaction of [Ni(LH₃)₂)] with Cu²⁺ salt and a monodentate ligand (X = SCN⁻, CN⁻, or N ₃ ⁻ ). The structures of both the new symmetrical vicinal dioxime and its complexes were identified by elemental analyses, IR, ¹H NMR, UV-VIS spectra, and magnetic susceptibility. The elemental analyses and spectral data indicate that the hydrazone side of ligand acts as a O,N,O′ tridentate and the fourth position is occupied with monodentate anion such as SCN⁻, CN⁻, N ₃ ⁻ .     

Iron(III) complexes on the basis of azomethine derived from 4,4′-dodecyloxybenzoyloxybenzoyl-4-oxy-2-hydroxybenzaldehyde

This work deals with the synthesis and investigation of phase behavior of iron(III)-containing complexes of linear azomethine derived from 4,4′-dodecyloxybenzoyloxybenzoyl-4-oxy-2-hydroxybenzaldehyde with NO₃⁻, PF₆⁻, Cl⁻, and BF₄⁻ counterions. All semiproducts and target substances are characterized by TLC, elemental analysis, IR and NMR spectroscopy, and melting points. It is established that the reaction of Schiff base with metal salts at room temperature leads to the formation of complexes having presumably the linear structure. Phase behavior of the compounds obtained depending on the nature of counterion was studied.     

Development of new methods for the analysis of carboxylic acids and carbonyl compounds in size classified raindrops by CE for application in modelling atmospheric processes

Summary At the present time the formation processes of clouds and precipitation are not totally understood. Because cloud- and raindroplets are major sinks for chemical species in the atmosphere it is important to understand the physical and the chemical processes which occur during precipitation. The development of models is hindered by the scarcity of information about the scavenging of gases or aerosol particles by raindrops of different sizes. These processes can only be investigated by field experiments using microanalytical methods and analysing single raindrops as well as size-classified raindrop samples. Raindrops were collected according to their size by freezing them in liquid nitrogen (“Guttalgor” method). Sample volumes of the smallest raindrop sizes (radius <200μm) were usually smaller than 2 μL. The analysis of microvolumina in the size range of μL down to pL required the development of methods designed especially for this purpose. Analysis of rain samples was carried out by capillary electrophoresis. Organic acids were determined using a new electrolyte system for indirect detection. With this system it was possible to determine monocarboxylic acids (C₁−C₄) dicarboxylic acids (C₂−C₄, C₉) and inorganic anions (Cl⁻, NO₃ ⁻, SO₄ ²⁻) in the rain samples. Carbonyl compounds were analysed after derivatisation with dansylhydrazine using direct UV-detection. The system allows the identification of aliphatic carbonyl compounds (C₁−C₃, C₅) as well as benzaldehyde. It was found that carbonyl compounds and carboxylic acids showed concentration maxima at different raindrop radii. These concentration maxima are a consequence of particle scavenging. By using the results of a former experiment we concluded that the two species are located on different aerosol particle sizes. Reasons for the different particle sizes where these species are located are discussed. Presented at the 21^st ISC held in Stuttgart, Germany, 15^th–20^th September, 1996     

Spin crossover in iron(II) complexes with tris(pyrazol-1-yl)methane

Mononuclear iron(II) coordination compounds with tris(pyrazol-1-yl)methane (HC(Pz)₃) described as [Fe{HC(Pz)₃}₂]A₂ × nH₂O, where A = Cl⁻, Br⁻, I⁻, 1/2 SO₄²⁻, n = 0–7, were synthesized. The compounds were studied by static magnetic susceptibility measurements, IR and UV/Vis spectroscopy, and powder X-ray diffraction. The crystal and molecular structures of all compounds were determined by single crystal X-ray diffraction.     

Synthesis and anion recognition of neutral receptors based on multiamide calix[4]arene

Two multiamide calix[4]arenes (5, 6) were synthesized and characterized by NMR, MS and elemental analysis. The binding properties of receptors with some anions (π-O₂NPhOPO₃²⁻, π-O₂NPhO⁻, H₂PO₄⁻, Ac⁻, Cl⁻, Br⁻ and I⁻) were studied by UV-Vis spectra. The results indicate that the tetraamide calix[4]arenes (5, 6) have a good selectivity to the anions containing aromatic ring (π-O₂NPhOPO₃ ²⁻, π-O₂NPhO⁻). The 1 : 1 complexes between host and guest were formed through multiple hydrogen bonding and π-π interactions. The hosts 5 and 6 also show a definite binding ability for the anions (H₂PO₄⁻, Ac⁻, Cl⁻) that have no ultraviolet absorption, which provides a simple method of spectrum detection for these anions.     

Extraction of pertechnetate with tetraphenylphosphonium in the presence of various acids, salts and hydroxides

Solvent extraction of pertechnetate anions from aqueous solutions of some mineral acids (HCl, HNO₃, HClO₄, H₂SO₄), (NaCl, NaNO₃, NaClO₄, K₂CrO₄, NaCO₃), NaOH and NH₄OH by tetraphenylphosphonium chloride in chloroform and nitrobenzene was studied. The results are presented in the form of the dependencies of extraction characteristics of TcO ₄ ⁻ (distribution ratio, percentage of extraction) on the (C₆H₅)₄PCl, H⁺ and competitive anion concentrations. The solvent extraction of sub-and super-stoichiometric ratio of TcO ₄ ⁻ : (C₆H₅)₄P⁺ was performed. The extraction constant values of ion pairs TcO ₄ ⁻ −Cl⁻, TcO ₄ ⁻ −NO ₃ ⁻ , TcO ₄ ⁻ −ClO ₄ ⁻ and of individual anions TcO ₄ ⁻ , Cl⁻, NO ₃ ⁻ , ClO ₄ ⁻ were calculated.     

Design and evaluation of highly sensitive luminescent terbium sensor for hypochlorite in water

A novel terbium 2-methyl-benzoimidazole-5-carboxylic acid complex was prepared and incorporated into silica matrix (tetraethoxysilane) using a mild sol–gel technique. We then successfully fabricated a terbium luminescent xerogel, which maintained intense green emission even in pure water. The emission was rapidly (~1 s) quenched by ClO⁻ (detection limit 10⁻⁵ M) but not NO₃ ⁻, CH₃COO⁻, F⁻, Cl⁻, Br⁻, I⁻, CO₃ ⁻, and OH⁻. The selectivity appears to be due to the high vibrational energy of ClO⁻ as well as its strong oxidation capability.     

A new unsymmetrical vic-dioxime bearing salicylaldehyde 4-aminobenzoylhydrazone and its homo-and heterotrinuclear complexes with copper(II) and nickel(II) ions

A new vic-dioxime, N-{4-[[(2-hydroxyphenyl)methylene]hydrazinecarbonyl]phenyl}aminoglyoxime (H₃L), was prepared by the reaction of anti-chloroglyoxime with salicylaldehyde 4-aminobenzoylhydrazone. The reaction of H₃L with Cu(II) salts and an appropriate simple ligand gave only homotrinuclear complexes [Cu₃(HL)₂X₂], whereas the reaction of H₃L with Ni(II) salts gave mono-and homotrinuclear complexes [Ni(H₂L)₂ and Ni₃(HL)₂X₂]. Also, heterotrinuclear complexes of H₃L were prepared by the reaction of Ni(H₂L)₂ with Cu(II) salt and an appropriate simple ligand, [NiCu₂(HL)₂X₂], X = Cl⁻, NO ₃ ⁻ , SCN⁻, CN⁻, and N ₃ ⁻ . The new vic-dioxime and its complexes were identified by elemental analyses, IR, ¹H NMR, UV-VIS, magnetic susceptibility, and mass spectral data. The elemental analyses and spectral data indicated that the hydrazone side of H₃L acted as monobasic tridentate and the fourth position was occupied by simple ligands, such as Cl⁻, NO ₃ ⁻ , SCN⁻, CN⁻, and N ₃ ⁻ . The text was submitted by the author in English.     

A theoretical investigation on structures of tripodal thiourea derivatives and their anion recognition

The structural geometries of three tripodal thiourea receptors, i.e. 1,3,5-triethyl-2,4,6-tris[(N′-methylthioureido)methyl]benzene (1), tris[N′-methyl-N-(2-aminoethyl)thiourea]methane (2), tris[N′-methyl-N-(2-aminoethyl)thiourea]amine (3), and their complexes with F⁻, Cl⁻, Br⁻, I⁻, NO₃ ⁻, CO₃ ²⁻, SO₄ ²⁻, HSO₄ ⁻, PO₄ ³⁻, HPO₄ ²⁻ and H₂PO₄ ⁻ were obtained using the density functional theory calculations. Electronic and thermodynamic properties of anion binding complexes of the receptors 1, 2 and 3 were investigated. Recognition abilities of all the receptors in terms of selectivity coefficients are reported. Intermolecular interactions in all the studied complexes occurring via multi-point hydrogen bonding were found. The receptors 1, 2 and 3 were found to be excellent selectivity for phosphate ion and their binding free energy for the phosphate ion are −292.57, −291.77 and −295.01 kcal/mol, respectively.     

Synthesis,characterization, volatilization,alcoholysis and hydrolytic studies of nonaalkoxodititanatocopper(II) complexes

Heterobimetallic alkoxides of Cu(II) of the types [Cu{η⁴-Ti₂(OEt)₉}Cl] (1) and [Cu{η³-Ti₂(OR)₉}₂] [R = Prⁱ (2), R = Et(3)] have been prepared for the first time by the reactions of CuCl₂ · xROH with KTi₂(OR)₉ in 1:1 and 1:2 molar ratios, respectively, in benzene medium. The chloro(nonaalkoxo dititanato)copper(II) complexes undergo chloride replacement reactions by a variety of monodentate alkoxo (⁻OPrⁱ, ⁻OEt) and chelating [Al(OPrⁱ) ₄ ⁻ , Al(OEt) ₄ ⁻ , Nb(OPrⁱ) ₆ ⁻ , Zr₂(OPrⁱ) ₉ ⁻ , Sn₂(OPrⁱ) ₉ ⁻ , and Sn₂(OEt) ₉ ⁻ ] ligands to form interesting hetero(bi-and tri-)metallic complexes. Alcoholysis (with methyl alcohol and tert-butyl alcohol) and hydrolytic [with Ba(OH)₂ · 8H₂O powder] reactions of a few typical compounds have also been investigated. All of these have been characterized by elemental analyses, molecular weight determinations, spectral (i.r. and visible) and magnetic studies. On attempted volatilization under reduced pressure these complexes liberated titanium alkoxides as a volatile component leaving nonvolatile residues.     

Ion chromatographic and spectrometric determination of water-soluble compounds in airborne particulates, and their correlations in an industrial area in Attica, Greece

In the time period from June 2005 to May 2006 in 42 sampling campaigns 84 filter samples of airborne particulate matter, coarse (PM_10–2.5) and fine (PM_2.5), were collected using a Gent stacked filter unit in the coastal industrial area of Aspropyrgos in Attica, Greece. The average PM₁₀ (PM_10–2.5 + PM_2.5) concentration was found to be 66 μg · m⁻³, exceeding more than 1.6 times the annual limit of 40 μg · m⁻³. The samples were analysed for Cl⁻, NO₃ ⁻, SO₄ ²⁻, Ca²⁺, Mg²⁺, Na⁺, K⁺ and NH₄ ⁺ using ion chromatography. The data were compared with results obtained with other spectrometric methods, such as inductively coupled plasma-atomic emission spectrometry, atomic absorption spectrometry, energy dispersive X-ray fluorescence and reflectometry. The determined average ionic content comprised about 44% of the PM₁₀ mass. The ionic composition, as well as the possible matrix compounds in both fractions were evaluated by dividing the sampling period into summer and winter season. In the PM_10–2.5/PM_2.5 fraction in summer time the concentrations of Ca²⁺, Mg₂₊ and NO₃ ⁻ were enriched in the coarse fraction. In winter time all species were enriched in the coarse fraction, especially Ca²⁺, Cl⁻ and NO₃ ⁻. NH₄ ⁺ was constantly higher in the fine fraction in summer as well as in winter time. Factor analysis was applied to obtain correlations between cations and anions leading to matrix compounds in both fractions. From the evaluation of the results obtained, some of the local air pollution sources could be identified. Correspondence: Klaus-Michael Ochsenkühn, Laboratory for Trace Element Studies, Institute of Physical Chemistry, NCSR “Demokritos”, Aghia Paraskevi 15310, Athens, Greece     

A sandwich anion receptor by a BODIPY dye bearing two calix[4]pyrrole units

A novel dicalix[4]pyrrolyl-substituted 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) dye I with an absorption peak at approximately 670 nm and an emission peak at about 690 nm was prepared. As an anion receptor, I displayed a red shift in absorption spectra and fluorescence quenching in varying degrees in the presence of F⁻, AcO⁻, H₂PO₄⁻, or Cl⁻. Compared with the parent calix[4]pyrrole, a representative anion receptor, I exhibited a stronger affinity to these anions due to the formation of a sandwich complex through multiple hydrogen-bonding interactions.     

Synthesis and characterization of complexes of Co(II), Ni(II), Cu(II), Zn(II), and Cd(II) with macrocycle 3,4,11,12-tetraoxo-1,2,5,6,9,10,13,14-octaaza-cyclohexadeca-6,8,14,16-tetraene and their biological screening

A new series of complexes is synthesized by template condensation of glyoxal and oxalyldihydrazide in methanolic medium in the presence of divalent cobalt, nickel, copper, zinc and cadmium salts forming complexes of the type: [M(C₈H₈N₈O₄)X₂] where M = Co^(II), Ni^(II), Cu^(II), Zn^(II), Cd^(II) and X = Cl⁻¹, Br⁻¹, NO ₃ ⁻¹ , OAc⁻¹. The complexes have been characterized with the help of elemental analyses, conductance measurements, magnetic susceptibility measurements, electronic, n.m.r., infrared and far infrared spectral studies. On the basis of these studies, a six coordinate octahedral geometry for these complexes has been proposed. The biological activities of the metal complexes have been tested in vitro against a number of pathogenic bacteria to assess their inhibiting potential. Most of the compounds have been found to exhibit remarkable antibacterial activities.     

Development of activated carbon from vine shoots by physical and?chemical activation methods. Some insight into activation mechanisms

Activated carbons (ACs) are prepared from vine shoots (VS) by the method of physical activation in air, CO₂ and steam atmospheres and by the method of chemical activation with H₃PO₄, ZnCl₂ and KOH aqueous solutions. The ACs were characterized texturally by N₂ adsorption at −196 °C, mercury porosimetry, and density measurements. The method of chemical activation has been proved to be more effective than the method of physical activation to prepare ACs with a well-developed porosity. ACs with high micro- and mesopore volumes are prepared with ZnCl₂ and H₃PO₄. Using ZnCl₂, the volume of micropores is 0.62 cm³ g⁻¹ and the volume of mesopores is 0.81 cm³ g⁻¹. A greater development of macroporosity is obtained by KOH activation. The volume of macropores is as high as 1.13 cm³ g⁻¹ for the resulting AC. Yield of the process of preparation of the ACs is low for the method of chemical activation. Some insights into the performance of the activating agents in the activation process are provided.     

XRD and UV-Vis diffuse reflectance analysis of CeO2-ZrO2 solid solutions synthesized by combustion method

A series of ceria-incorporated zirconia (Ce_1−xZr_xO₂,x = 0 to 1) solid solutions were prepared by employing the solution combustion synthesis route. The products were characterized by XRD and UV-Vis-NIR diffuse reflectance spectroscopy. The materials are crystalline in nature and the lattice parameters of the solid solution series follow Vegard’s law. Diffuse reflectance spectra of the solid solutions in the UV region show two intense bands at 250 and 297 nm which are assigned respectively to Ce³⁺ ← O²⁻and Ce⁴⁺ ← O²⁻ charge transfer transitions. The two vibrational bands in 6960 cm⁻¹ and 5168 cm⁻¹ in the NIR region indicate the presence of surface hydroxyl groups on these materials.     

Estimation of the specific content and nature of sorption sites of iron(<Emphasis Type="SmallCaps">III</Emphasis>) and zirconium(<Emphasis Type="SmallCaps">IV</Emphasis>) oxyhydroxides

The sorption of anions H₂PO₄ ⁻, HPO₄ ²⁻, PO₄ ³⁻, [Fe(CN)₆]³⁻, and [Fe(CN)₆]⁴⁻ from aqueous solutions on the surface of Fe^III and Zr^IV oxyhydroxide hydrogels freshly precipitated at pH 4–13 was studied. The region of sorbate concentrations was from 0.00025 to 0.06 mol L⁻¹. The plots of the anion uptakes vs. their equilibrium concentrations are represented by isotherms of the first type, which are well described by the Langmuir equation if the quantity of the amount adsorbed is expressed as mol-site g⁻¹. The maximum uptakes and constants of the Langmuir equation were calculated. The phosphate anions occupy the same number of sorption sites on the sorbents precipitated at different pH. The average specific content of sorption sites for the ferro- and zirconogels in the metastability period is independent of the pH of their precipitation, being 3.1·10⁻³ and 3.2·10⁻³ mol-site g⁻¹, respectively. The [Fe(CN)₆]³⁻ and [Fe(CN)₆]⁴⁻ anions are sorbed only on the positively charged sites of the hydrogels and occupy not more than 2·10 mol-site g⁻¹ in the studied interval of pH of precipitation. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1736—1741, August, 2005.     

Kinetic and thermodynamic sorption study of radiocobalt by magnetic hydroxyapatite nanoparticles

A novel composite adsorbent, magnetite/hydroxyapatite (Fe₃O₄/HAP) composites, was prepared by biowaste chicken eggshell for the purpose of removing radiocobalt from aqueous solutions. It highlighted that more than 92% Co(II) could be removed by using the developed composites under the experimental conditions. The maximum sorption capacity of Co(II) on Fe₃O₄/HAP composites was 6.9 × 10⁻⁴ mol/g. The coexisted foreign ions, e.g., ClO₄ ⁻, NO₃ ⁻, Cl⁻, Na⁺ and K⁺, did not interfere the elimination of Co(II) from aqueous solutions, while Mg²⁺ did. The sorption process was found to be controlled well by pseudo-second-order and intra-particle diffusion models, and the equilibrium data were simulated by Langmuir model very well with high correlation coefficients. The thermodynamic parameters confirmed the spontaneity and endothermic nature of Co(II) sorption processes. After sorption, the Fe₃O₄/HAP composites could be effectively and fleetly separated from aqueous solutions by magnetic separation technique in large scale. The Fe₃O₄/HAP composites are suitable materials in the preconcentration of Co(II) from large volumes of aqueous solutions.     

Synthesis of nanosized materials for lithium-ion batteries by mechanical activation. Studies of their structure and properties

This short review reports on the synthesis of nanosized electrode materials for lithium-ion batteries by mechanical activation (MA) and studies of their properties. Different structural types of compounds were considered, namely, compounds with a layered (LiNi_{1 − x − y} Co _x Mn _y O₂), spinel (LiMn₂O₄, Li₄Ti₅O₁₂), and framework (LiFePO₄, LiTi₂(PO₄)₃) structures. The compounds also differed in electronegativity, which varied from 10⁻⁴ S cm⁻¹ for LiCoO₂ to 10⁻⁹ S cm⁻¹ for LiFePO₄. The preliminary MA of mixtures of reagents in energy intensive mechanoactivators led to the formation of highly reactive precursors, and annealing of the latter formed nanosized products (the mean particle size is 50–200 nm). The local structure of the synthesized compounds and the composition of their surface were studied by spectral methods. An increase in the dispersity and defect concentration, especially in the region of the surface, improved some electrochemical characteristics. It increased the stability during cycling (LiMn₂O₄, at 3 V) and the regions of the formation of solid solutions during cycling (Li₄Ti₅O₁₂, LiFePO₄), led to growth of surface Li-ion conductivity (LiTi₂(PO₄)₃), etc. The mechanochemical approach was also used for the synthesis of core-shell type composite materials (LiFePO₄/C, LiCoO₂/MeO _x ) and materials based on two active electrode components (LiCoO₂/LiMn₂O₄).