Atomic structure of nickel phthalocyanine probed by X-ray absorption spectroscopy and density functional simulations

The local atomic structure of Ni in nickel phthalocyanine was studied by K-edge X-ray absorption fine structure spectroscopy. The obtained inter atomic nickel-nitrogen distance differs from the reference X-ray diffraction data so an additional study was performed within density functional theory framework. The justification of the used theoretical approach was provided by a comparison of theoretical free electron densities of states with experimental Ni K-edge X-ray absorption near edge spectra. The refined Ni local environment retain the reference structure of the molecule except for the length of Ni-N bond which increases to 1.90 Å.     

Preparation and magnetic properties of zinc phthalocyanines homogeneously doped with alkaline metals

A method for preparation of homogeneous samples of metal-phthalocyanines doped with alkaline metals was developed. Polycrystalline samples of zinc phthalocyanines doped with sodium, potassium, and rubidium atoms were investigated. We measured the temperature dependence of ESR spectra of prepared samples and studied their composition and structure. It is shown that their magnetic properties depend strongly on the degree of doping as well as on the subsequent grinding and annealing.     

Investigation of carbon microspheres prepared by solid-phase pyrolysis of metal-free phthalocyanine

By using solid-phase pyrolysis of metal-free phthalocyanine (H₂C₃₂N₈H₁₆) we have prepared carbon microspheres with a mean diameter from 2–3.5 μm and sufficiently narrow size distribution. The elemental composition, structure and morphology of samples were studied by scanning electron microscopy, energy-dispersive X-ray microanalysis, and X-ray diffraction. A strong electron paramagnetism was revealed in microspheres.     

Nickel nanoparticles in carbon structures prepared by solid-phase pyrolysis of nickel-phthalocyanine

Nanoscale magnetite (Fe₃O₄) (<15?nm) is known to remove arsenic efficiently but is very difficult to separate or require high magnetic fields to separate out from the waste water after treatment. Anisotropic hexagonal ferrite (BaFe₁₂O₁₉, BHF) is a well-known permanent magnet (i.e., fridge magnets) and attractive due to its low cost in making large quantities. BHF offers a viable alternative to magnetite nanocrystals for arsenic removal since it features surfaces similar to iron oxides but with much enhanced magnetism. Herein, we employ BHF nanocrystalline materials for the first time in arsenic removal from wastewater. Our results show better (75?%) arsenic removal than magnetite of the similar sizes. The BHF nanoparticles, 6.06?±?0.52?nm synthesized by thermolysis method at 320?°C do not show hexagonal phase, however, subsequent annealing at 750?°C produced pure hexagonal BHF in >200?nm assemblies. By using BHF, we demonstrate that nanoparticle removal is more efficient and fixed bed type cartridge applications are more possible.     

Characterization of zinc and zinc cyanide nanoparticles in carbon matrices prepared by solid-phase pyrolysis of zinc-phthalocyanine

Using solid-phase pyrolysis of Zn-phthalocyanine (ZnC₃₂H₁₆N₈), we have prepared zinc and zinc cyanide nanoparticles in carbon matrices with a zinc concentration of 3 at %. The structure and composition of samples were investigated by the methods of scanning electron microscopy, X-ray diffraction, and Raman spectroscopy. It is shown that at low pyrolysis temperature (700°C) only the Zn nanoparticles are formed, whereas at higher temperature (900°C) a certain amount of Zn(CN)₂ nanoparticles are also synthesized. The mean diameter of nanoparticles is about 150 nm, and their size distribution has a logarithmically normal shape.     

Formation of nickel magnetic nanoparticles and modification of nickel phthalocyanine matrix by sodium doping

Data for the vapor-phase doping (300°C) of nickel phthalocyanine (NiPc) by sodium taken in different concentrations (x), as well as structural analysis data for Na _{x = 0.2}NiPc, Na _{x = 1}NiPc, and Na _{x = 3}NiPc samples, have been reported. The structure of the samples and their atomic configuration versus the doping level have been studied by transmission electron microscopy, Raman scattering, X-ray diffraction, X-ray absorption spectroscopy, and extended X-ray absorption fine structure (EXAFS) spectroscopy. The structural parameters of Ni–N, Ni–C, and Ni–Ni bonds have been determined, and it has been found that, at a low level of doping by sodium, local structural distortions are observed in some molecules of the NiPc matrix near nickel atoms. The fraction of these molecules grows as the doping level rises from x = 0.2 to x = 1.0. It has been shown that doping changes the oscillation mode of light atoms, which indicates a rise in the electron concentration on five- and six-membered rings. At a high level of sodium doping (x = 3.0), nickel nanoparticles with a mean size of 20 nm and molecule decomposition products have been observed in the NiPc matrix. It has been found that the fraction of nickel atoms in the Na _{x = 3}NiPc nanoparticles as estimated from EXAFS data is sufficient for the room-temperature magnetic properties of the samples to persist for a long time.     

Reaction of Haloacrylic Acids with Phosphorus Nucleophiles

-Chloroacrylic acid reacts with triphenylphosphine to give (E)-(2-carboxyvinyl)triphenylphosphonium chloride. The same reaction with -halomethacrylic acids yields, depending on the temperature, either (2-carboxypropenyl)triphenylphosphonium halides or their isomeric (2-carboxyallyl)triphenylphosphonium halides. The possibility of unusual isomerization of the first compounds to the latter is shown. Synthesis of 1,2-(diphenylphosphinoyl)ethane from -chloroacrylic acid is carried out.     

Homotopic invariance of infinite-dimensional homotopic groups of Hilbert space subsets

The paper discusses some equivalent ways of construction of infinite-dimensional homotopic groups of subsets and pairs of subsets in real Hilbert spaces. In the admissible class of K ₀-continuous mappings, the homotopic invariance of the mentioned groups and their isomorphism are demonstrated in the case where the basic points belong to the same component of K ₀-linear connectivity.     

Copper-carbon nanocomposites prepared by sold-phase pyrolysis of copper phthalocyanine

By using solid-phase pyrolysis of copper phthalocyanine we have prepared copper nanoparticles in carbon matrices. The elemental composition, structure, and morphology of nanocomposites were investigated by scanning electron microscopy, energy dispersive X-ray microanalysis, and X-ray diffraction. Depending on the temperature and time of pyrolysis, the sizes of copper nanoparticles can be varied from 10 nm to 400 nm. The structure of carbon matrices also strongly depends on the pyrolysis conditions, which allows us to synthesize nanocomposites with given properties.     

Helix-coil transition of biopolymers in solvents interacting in competitive and non-competitive ways

Within the framework of generalized model of polypeptide chain, on the basis of the Hamiltonian of model of solvent, which interacts with a biopolymer in both competitive and noncompetitive ways, introduced earlier, analytical expressions are obtained and thermodynamic and other averaged parameters are calculated for both the repeating units of the biopolymer and the solvent molecules. Different cases of relations between parameters of competitive and non-competitive bonding are considered and processes of melting and alignment are studied. It is shown that these processes are accompanied by changes in solvation and redistribution of solvent molecules between the helical and coiled portions of the chain.