Synthesis and physicochemical properties of chelating sorbents containing functional groups of N-aryl-3-aminopropionic acids

Two types of chelating sorbents with different types of addition of iminodipropionate groups to a polymeric matrix were synthesized: carboxyethylated aminopolystyrene (sorbent 1) based on linear polystyrene and carboxyethylaminomethylpolystyrene (sorbent 2) based on the copolymer of styrene and divinylbenzene. The ionization constants and concentrations of functional groups of the sorbents (exchange capacity for hydrogen ions) were determined. The sorbents exhibit high selectivity for copper(II) ions with the maximum of sorption from ammonia—acetate buffer solutions lying in a range of pH 5.0–7.5. The time needed for a solution of copper(II)—sorbent system with continuous stirring to reach exchange equilibrium is 3.5 and 2 h for sorbents 1 and 2, respectively. The exchange capacity for copper(II) ions is 2.54 and 0.10 mmol g⁻¹, respectively. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 800–806, May, 2006.     

Applying reactive ionic-beam etching to correcting the shape of X-ray mirrors

A procedure for correcting the shape of cylindrical surfaces by means of reactive ionic-beam etching is presented. The results from an experiment on manufacturing a glass surface as an elliptical cylinder are shown.     

New molecular magnetic metals: κ-(BDH-TTP)4CuCl4·(H2O)n and κ-(BDH-TTP)2[CuCl4]0.67·(H2O)0.33 (BDH-TTP is 2,5-bis(1,3-dithiolan-2-ylidene)-1,3,4,6-tetrathiapentalene)

New radical cation salts based on 2,5-bis(1,3-dithiolan-2-ylidene)-1,3,4,6-tetrathiapentalene (BDH-TTP), viz., κ-(BDH-TTP)₄CuCl₄·(H₂O) _n (1) and κ-(BDH-TTP)₂[CuCl₄]_0.67· ·(H₂O)_0.33 (2), were synthesized and structurally characterized. Single crystals were prepared by the electrochemical oxidation of BDH-TTP under galvanostatic conditions. The X-ray diffraction study showed that the salts have layered structures characterized by the presence of κ-type BDH-TTP conducting layers. These layers alternate with the complex anions composed of [CuCl₄]²⁻ units and water molecules. Both salts exhibit the temperature dependence of the metallic conductivity down to 4.2 K. Spin-spin antiferromagnetic correlations in the Cu²⁺ subsystem were observed in the crystals of 2.     

The nature of transitions in electronic absorption spectra of radical cations of dipyrroles with phenylene bridging groups

The electronic absorption spectra of radical cations of dipyrroles with a phenylene bridge were studied by laser flash photolysis and quantum chemical methods. Intense absorption bands of the radical cations in the visible region (λ_max ≈ 500 nm, ε_max > 2 · 10⁴ L mol⁻¹ cm⁻¹) are caused by excitation of electrons from single occupied MOs to the LUMO. In the near IR region, calculations predict additional, relatively intense (f≈ 0.27–0.29) electronic transitions associated with excitation of electrons from low-lying MOs to the single occupied MO.     

Structure of (BEDT-TTF)-Based Organic Metals with Photochromic Nitroprusside Anion (BEDT-TTF)4M[FeNO(CN)5]2, where M = Na+, K+, NH+4, Tl+, Rb+, and Cs+

The crystal and molecular structures of a family of three-component radical cation salts bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF), (BEDT-TTF)₄M[NP]₂, where M = Na⁺, K⁺, NH⁺ ₄, Tl⁺, Rb⁺, and Cs⁺and NP is the nitroprusside anion [FeNO(CN)₅]^2–, are studied by X-ray structure analysis. These salts are isostructural and behave as stable metals down to helium temperatures. Their structures are characterized by radical cation layers of the "-type alternating with layers of complex anions [M⁺(NP^2–)₂]^3–. The conducting radical cation system and photochromic nitroprusside anion in the crystals were shown to affect each other. On the one hand, this changes the geometric parameters of the nitroprusside anion as compared to those of the Na₂[NP] · 2H₂O crystals in the ground state and, on the other hand, makes the geometries of the two crystallographically independent BEDT-TTF molecules with a different number of shortened contacts with the anion different. Based on the data of crystallochemical analysis of the (BEDT-TTF)₄M[FeNO(CN)₅]₂structures, we suggest their possible routes of chemical modification with the purpose of changing their physical properties.     

Structural features of low-dimensional molecular conductors—Representatives of new hybrid polyfunctional materials: Review

The crystal structures of the family of low-dimensional molecular conductors based on radical cation salts of different organic π donors with photochromic and magnetic metal complexes as anions have been considered. This class of supramolecular systems demonstrates a large variety of structural types and a wide range of transport properties. The specificity of the structure and properties of such hybrid materials is illustrated by several examples. The crystallochemical analysis of the conductors considered indicates the possibility of purposeful control of their transport properties via changing of the charge, sizes, shape, and symmetry of the anionic block components. The specificity of the crystal structure and properties of some organic conductors shows that such systems can be used as model systems in the study of new physical phenomena related to electron correlation and effects of charge ordering.     

Synthesis and electrochemical characterization of dipyrroles separated by diphenyleneoxide and diphenylenesulfide spacers via the Trofimov reaction

4,4′-Bis[2-(1-vinylpyrrolyl)]diphenyloxide, 4,4′-bis(2-pyrrolyl)diphenylsulfide, 4-(2-pyrrolyl)-4′-[2-(1-vinylpyrrolyl)]diphenylsulfide and 4,4′-bis[2-(1-vinylpyrrolyl)]diphenylsulfide have been synthesized in a one-pot procedure from oximes of corresponding diacetylphenylenoxide and -sulfide through their reaction with acetylene in the MOH-DMSO systems (M=Li, K) at 80-130 °C under pressure of 10-15 atm, thus illustrating applicability and general character of the reaction of synthesis of diverse dipyrrole-phenylene assemblies and their N-vinyl derivatives. Two of the pipyrroles are promising for creating new conducting polymers with sulfur and oxygen atoms in the conjugation chain and for the study of the influence of the diphenyleneheteroatom moiety on conductivity of final polymer products. For the dipyrroles with the diphenyleneheteroatom moieties and 1,4-phenylene spacer the luminescence characteristics were determined.     

On the problems of the application of atomic-force microscopes for studying the surface roughness of elements for imaging optics

The key problems of applying atomic-force microscopes when studying the surface roughness of elements for imaging optics are discussed. Special attention is paid to optics of ultrahigh spatial resolution with an operating wavelength of no shorter than 100 nm. It is proposed that a specialized microscope for optical applications equipped with a tetraaxial goniometer be developed.