Reaction of BSA,CT-DNA,Adenine and Guanine with [Pt(RaaiR′)Cl<Subscript>2</Subscript>] and Characterization of the Products [Pt(RaaiR′)(NB)(H<Subscript>2</Subscript>O)](PF<Subscript>6</Subscript>)<Subscript>2</Subscript>] [RaaiR′=1-alkyl-2-(arylazo)imidazole]

The reaction of [Pt(RaaiR′)(solvent)₂]²⁺ with nucleobases (NB), adenine and guanine was studied and the products [Pt(RaaiR′)(NB)(H₂O)](PF₆)₂RaaiR′ = 1-alkyl-2-(arylazo)imidazole, R′ = Me (1), Et (2); R = H (a),OMe (b), NO₂(c)] characterized by i.r, u.v.–vis. and ¹H-n.m.r spectroscopy. The solution spectra exhibit metal-to-ligand charge-transfer transitions (MLCT) and intra-ligand charge-transfer transitions. The position and symmetry of the bands depend on the nucleobase and arylazoimidazole. The coordination of the ligand is supported by ¹H-n.m.r. spectral data. The redox property has been examined by cyclic voltammetric technique and shows the involvement of the azo group of the chelated ligand, RaaiR′ in the reduction process along with the irreversible reduction of the coordinated nucleobase. Binding with Bovine Serum Albumin (BSA) and Calf Thymus DNA was performed spectrophotometrically in the physiological buffer medium and spectral profile was recorded in 24 h.     

A novel series of sulphur-bridged ruthenium-molybdenum complexes: [(RaaiR′)<Subscript>2</Subscript> Ru(μ-S)<Subscript>2</Subscript>Mo(OH)<Subscript>2</Subscript>]. Synthesis,spectroscopic and electrochemical characterization. RaaiR′=1-alkyl-2-(arylazo) imidazole

The reaction of ctc-[Ru(RaaiR′)₂Cl₂] (1) [RaaiR′ = 1-alkyl-2-(arylazo)imidazole, p-R-C₆H₄-N=N-C₃H₂NN(1)-R′, R = H (a), Me (b), Cl (c), R′ = Me (2), Et (3), Bz (4)] with (NH₄)₂MoS₄ in aqueous MeOH afforded red-violet mixed ligand complexes of the type [(RaaiR′)₂Ru(μ-S)₂Mo(OH)₂] (2–4). In complexes (2–4) the terminal Mo=S bonds of the MoS₄²⁻ unit become hydroxylated and the molybdenum ion is reduced from the starting Mo^VI in MoS₄²⁻ to Mo^IV in the final product (2–4). The solution electronic spectra exhibit a strong MLCT band at 550–570 nm in DCM. Cyclic voltammograms show a Ru(III)/Ru(II) couple at 1.10–1.4 V, irreversible Mo(IV)/Mo(V) oxidations in the 1.66–1.72 V range, along with four successive reversible ligand reductions in the range −0.45–0.67 V (one electron), −0.82–1.12 V (one electron), and −1.44–1.90 V (simultaneously two electrons).     

Solubility and stability of (NH<Subscript>4</Subscript>)<Subscript>2</Subscript>SO<Subscript>4</Subscript>·H<Subscript>2</Subscript>O<Subscript>2</Subscript> in organic and aqueous-organic media

Solubility and stability of (NH₄)₂SO₄·H₂O₂ in organic solvents (glycerol, ethylene glycol, TOSOL-A40 OM antifreeze), in mixtures of an organic solvent and water, and in pure water was studied. Crystallographic properties of the ammonium sulfate precipitating from aqueous-organic solvents and aqueous solutions in various time intervals and differing from ordinary (NH₄)₂SO₄ in solubility and one of crystallographic parameters were analyzed.     

Synthesis and study of lead(II) uranate Pb(UO<Subscript>2</Subscript>)<Subscript>2</Subscript>O<Subscript>2</Subscript>(OH)<Subscript>2</Subscript>·H<Subscript>2</Subscript>O

An individual crystalline compound Pb(UO₂)₂O₂(OH)₂·(H₂O) was obtained by reaction of synthetic schoepite UO₃·2.25H₂O with an aqueous solution of lead(II) nitrate under hydrothermal conditions. The composition and structure of this compound were determined, and the processes of its dehydration and thermal decomposition were studied by chemical analysis, X-ray diffraction, IR spectroscopy, and thermography.     

Crystal structure and thermal properties of [Au(en)<Subscript>2</Subscript>]<Subscript>2</Subscript>[Cu(C<Subscript>2</Subscript>O<Subscript>4</Subscript>)<Subscript>2</Subscript>]<Subscript>3</Subscript>·8H<Subscript>2</Subscript>O

The crystal structure of a double complex salt of the composition [Au(en)₂]₂[Cu(C₂O₄)₂]₃·8H₂O (en = ethylenediamine) at 150 K is determined by single crystal X-ray diffraction. The crystal data for C₂₀H₄₈Au₂Cu₃N₈O₃₂ are: a = 9.1761(3) Å, b = 16.9749(6) Å, c = 13.4475(5) Å, β = 104.333(1)°, V = 2029.43(12) ų, P2₁/c space group, Z = 2, d _x = 2.450 g/cm³. It is demonstrated that the thermal decomposition of the double complex salt in a helium or hydrogen atmosphere affords the solid solution Au_0.4Cu_0.6.     

Characterization and thermal decomposition of Mg<Subscript>2</Subscript>KH(AsO<Subscript>4</Subscript>)<Subscript>2</Subscript>·15H<Subscript>2</Subscript>O

In this work, we present first data on the infrared and Raman spectroscopic characteristics, thermal analysis and solid-state transformations of Mg₂KH(AsO₄)₂·15H₂O, which is a unique example of an acid salt containing dimeric units [H(AsO₄)₂] in its crystal structure. The infrared and Raman spectra recorded at ambient conditions have been studied, and an assignment of the observed vibrational bands has been proposed considering the crystal structure data. The thermal behavior of Mg₂KH(AsO₄)₂·15H₂O has been investigated by simultaneous TG/DTA/mass spectrometry experiments in the temperature range up to 1000 °C at different heating rates, and new data on the thermal stability and thermal dehydration of Mg₂KH(AsO₄)₂·15H₂O have been obtained. The phase composition after the dehydration processes in the temperature interval of 300–650 °C has been studied by combination of powder XRD and IR spectroscopic analyses. The spectroscopic and thermal properties of Mg₂KH(AsO₄)₂·15H₂O have been compared to those of the isostructural phosphate salt Mg₂KH(PO₄)₂·15H₂O.     

Synthesis and crystal structure of complex [Mn(Imdc)<Subscript>2</Subscript>(H<Subscript>2</Subscript>O)<Subscript>2</Subscript>] · 2H<Subscript>2</Subscript>O and its interaction with DNA

Under hydrothermal conditions, the complex [Mn(lmdc)₂(H₂O)₂] · 2H₂O (I) was synthesized and characterized by elemental analysis and IR spectrum (HImdc = 4,5-imidazofedicarboxylic acid). The crystal structure of I was determined by single-crystal X-ray diffraction (crystallizing in the monoclinic crystal system, P ₂/c space group, a = 11.000(2), b = 7.1281(14), c = 12.696(3) Å, β = 122.45(3), Z = 2. In I, the Mn²⁺ ion was chelated by two Imdc with one of their nitrogen atoms and a carboxylic oxygen atom, while two water molecules occupy the axial position of the Mn atom forming a distorted octahedral geometry. Three-dimensional structure of I was formed by intermolecular hydrogen bonds. UV-Vis and fluorescence spectra of I interacting with DNA show that insertion is the main binding mode between I and fish sperm DNA. Gel electrophoresis shows that I cleaves both supercoiled and circular pBR322 DNA to form a small molecular fragment.     

Dissociation enthalpies and phase equilibrium for TBAB semi-clathrate hydrates of N<Subscript>2</Subscript>, CO<Subscript>2</Subscript>, N<Subscript>2</Subscript> + CO<Subscript>2</Subscript> and CH<Subscript>4</Subscript> + CO<Subscript>2</Subscript>

Tetra-n-butyl ammonium bromide (TBAB) semi-clathrate (sc) hydrates of gas are of prime importance in the secondary refrigeration domain and in the separation of gas molecules by molecular size. However, there is a scarcity of dissociation enthalpies under pressure of pure gases and gases mixtures for such systems. In addition, the phase equilibrium of TBAB sc hydrates of several pure gases is not well defined yet as a function of the TBAB concentration and as a function of the pressure. In this paper, dissociation enthalpies and the phase equilibrium of TBAB sc hydrates of gas have been investigated by differential scanning calorimetry (DSC) under pressure. Pure gases such as N₂ and CO₂ and gases mixtures such as N₂ +  CO₂ and CH₄ +  CO₂ were studied. To our knowledge, we present the first phase diagram of TBAB sc hydrates of N₂ for different pressures of gas in the TBAB concentration range from 0.170 to 0.350 wt. Enthalpies of dissociation of TBAB sc hydrates of pure gases and gases mixtures were determined as a function of the presssure for a compound with a congruent melting point whose hydration number corresponds to 26.     

Ionic mobility and electrophysical properties of solid solutions in PbF<Subscript>2</Subscript>–SbF<Subscript>3</Subscript> and PbF<Subscript>2</Subscript>–SnF<Subscript>2</Subscript>–SbF<Subscript>3</Subscript> systems

Ionic mobility and electrical conductivity of solid solutions with fluorite structure, obtained with solid-state approach in PbF₂–SbF₃ and PbF₂–SnF₂–SbF₃ systems, are studied by 19F NMR and electrochemical impedance spectroscopy methods. The 19F NMR spectra parameters, types of ion motions in the fluoride sublattice, and the ionic conductivity magnitude are shown to be determined by the temperature and fluoride concentration in the solid solutions. The solid solution specific conductivity in the PbF₂–SbF₃ and PbF₂–SnF₂–SbF₃ systems at 420–450 K is as high as ~10^–2 S/cm, which allows accounting the solid solutions as a base for preparation of functional materials.     

Synthesis and structure of the [Co(NioxH)<Subscript>2</Subscript>(Thio)<Subscript>2</Subscript>]<Subscript>2</Subscript>SO<Subscript>4</Subscript>·2H<Subscript>2</Subscript>O complex compound

A new Co(III) complex of 1,2-cyclohexanedionedioxime and thiocarbamide with an SO ₄ ^2? anion and solvation water molecules in the outer sphere has been synthesized and its structure has been defined. Orthorhombic crystals, a = 11.659(2) Å, b = 26.448(5) Å, c = 30.142(6) Å, V = 9295(3) Å ³, Z = 8, d_calc = 1.599 g/cm³, space group Pbca; final R index is 0.0578 for 8221 reflections with I > 2σ(I). In the octahedral Co(III) complex, two 1,2-cyclohexanedionedioxime residues lie in the equatorial plane, while two thiocarbamide molecules are in the axial plane. Intramolecular bonds: N-H…O and O-H…O type hydrogen bonds and π-π interactions that stabilize the complex cations. In crystal, the components are linked by N-H…O and O-H…O hydrogen bonds into a 3D framework.     

Phase and extraction equilibria in H<Subscript>2</Subscript>O–sulfonol–HCl (H<Subscript>2</Subscript>SO<Subscript>4</Subscript>) and H<Subscript>2</Subscript>O–sodium dodecyl sulfate–HCl (H<Subscript>2</Subscript>SO<Subscript>4</Subscript>) systems

Solubility isotherms of water–sulfonol–hydrochloric (or sulfuric) acid and water–sodium dodecyl sulfate–hydrochloric acid systems at 75°C and a water–sodium dodecyl sulfate–sulfuric acid system at 50°C are constructed. Regions of two-phase liquid equilibrium suitable for use in extraction are found. Concentration parameters for extraction are determined. The interfacial distribution of a series of metal ions with and without such additional complexing reagents as diantipyrylmethane and diantipyrylheptane is studied.     

Structure and thermal decomposition of Cs<Subscript>2</Subscript>HPO<Subscript>4</Subscript> · 2H<Subscript>2</Subscript>O

The thermal transformations of disubstituted cesium orthophosphate crystal hydrate under heating in air up to 400°C have been studied. The dehydration process occurs in two stages with the loss of 0.6 water molecules at 60?100°C and 1.4 water molecules at 100?160°C. Anhydrous Cs₂HPO₄ is stable up to 300°C and is completely converted into cesium pyrophosphate Cs₄P₂O₇ at 330°C. The structure of Cs₂HPO₄ · 2H₂O has been determined. The compound crystallizes in monoclinic space group P2₁/c and has the unit cell parameters a = 7.4761(5) Å, b = 14.2125(8) Å, c = 7.9603(6) Å, β = 116.914(5)°, V = 754.20(9) ų, and Z = 4 at?123°C. An earlier unknown polymorph of Cs₄P₂O₇ has been found. According to X-ray powder diffraction data, hexagonal space group Р6₃ has been proposed for the formed pyrophosphate.     

Synthesis and heat capacity study of stannates Dy<Subscript>2</Subscript>Sn<Subscript>2</Subscript>O<Subscript>7</Subscript> and Ho<Subscript>2</Subscript>Sn<Subscript>2</Subscript>O<Subscript>7</Subscript> in the range 370–1000 K

Stannates Dy₂Sn₂O₇ and Ho₂Sn₂O₇ are produced by solid-phase synthesis from Dy₂O₃ (Ho₂O₃)–SnO₂ stoichiometric mixtures by calcining at 1473 K. The molar heat capacity of holmium and dysprosium stannates is measured by differential scanning calorimetry (DSC) in the temperature range 370–1000 K. The experimental data are used to calculate thermodynamic properties (enthalpy change H°(T)–H°(370 K), entropy change S°(T)–S°(370 K), and the reduced Gibbs free energy Φ°(T)) of the synthesized compound.     

Osmium(IV) thiocarbamide complexes. Synthesis and crystal and molecular structures of [Os(Thio)<Subscript>2</Subscript>Cl<Subscript>4</Subscript>] · 2H<Subscript>2</Subscript>O

Tetrachlorobis(thiocarbamide)osmium(IV) dehydrate, [Os(Thio)₂Cl₄] · 2H₂O, was synthesized by the reaction of K₂[OsO₂(OH)₄] with thiocarbamide in 6 M HCl. The compound was characterized by chemical analysis and IR, UV, and X-ray photoelectron spectroscopies. The structure was determined by X-ray diffraction analysis. The coordination polyhedron of the osmium atom lying in the axis 2 is a distorted cis-octahedron formed by four chlorine atoms and two sulfur atoms of two monodentate thiocarbamide ligands: Os-S 2.3075(18) Å and Os-Cl 2.3625(18) Å (trans to Cl) and 2.4294(19) Å (trans to S). The conditions for the formation of the osmium(IV) thiocarbamide complexes in HCl solutions were determined using spectrophotometry, and the spectral characteristics of [Os(Thio)Cl₅]^? were obtained.     

Synthesis and X-ray diffraction study of Li(H<Subscript>3</Subscript>O)[UO<Subscript>2</Subscript>(C<Subscript>2</Subscript>O<Subscript>4</Subscript>)<Subscript>2</Subscript>(H<Subscript>2</Subscript>O)] · H<Subscript>2</Subscript>O

Single crystals of Li(H₃O)[UO₂(C₂O₄)₂(H₂O)] · H₂O (I) have been synthesized and studied by X-ray diffraction. Compound I crystallizes in the monoclinic crystal system with the unit cell parameters: a = 7.1682(10) Å, b = 29.639(6) Å, c = 6.6770(12) Å, β= 112.3(7)°, space group P 2₁/c, Z = 4, R = 4.36%. Structure I contains discrete mononuclear groups [UO₂(C₂O₄)₂(H₂O)]^2? ascribed to the crystal-chemical group AB ₂ ⁰¹ M¹ (A = UO₂ ²⁺, B⁰¹ =C₂O ₄ ^2? , M¹ = H₂O), which are “cross-linked” by the lithium ions into infinite layers {Li(UO₂)(C₂O₄)₂(H₂O)₂}^? perpendicular to [010]. The hydroxonium ions are located between adjacent uranium-containing layers. A hydrogen bond system involving water molecules, oxalate ions, and hydroxonium combines the anionic layers into a three-dimensional framework.     

Phase equilibria in the Nb<Subscript>2</Subscript>O<Subscript>5</Subscript>–CdO system and the thermal stability of Cd<Subscript>2</Subscript>Nb<Subscript>2</Subscript>O<Subscript>7</Subscript> and CdNb<Subscript>2</Subscript>O<Subscript>6</Subscript>

Phase equilibria were studied in the Nb₂O₅–CdO system in the Nb₂O₅-rich region including CdNb₂O₆ and Cd₂Nb₂O₇. It was determined that CdNb₂O₆ and Cd₂Nb₂O₇ in air are stable to 1150 and 1120°C, respectively, and that, above these temperatures, there is solid-phase decomposition of niobates with CdO release in the gas phase. Along with the cadmium oxide evaporation, the Cd₂Nb₂O₇ decomposition is accompanied by the formation of cadmium metaniobate CdNb₂O₆ and the CdNb₂O₆ decomposition results in the formation of niobium oxide Nb₂O₅. No thermal events were observed in the differential thermal analysis curve for a 1: 1 CdNb₂O₆–Cd₂Nb₂O₇ mixture heated to 1100°C in air, which suggests that there are neither phase transformations in cadmium niobates, nor a eutectic within this temperature and concentration ranges. A study of the morphology of compacted samples of niobates determined specific conditions for producing dense composite ceramics, a mixture of niobates, that is suitable for using as a dielectric material.     

Synthesis and crystal structures of [K(H<Subscript>2</Subscript>O)(Piv)]<Subscript>∞</Subscript> and [K<Subscript>2</Subscript>(Phen)(H<Subscript>2</Subscript>O)<Subscript>2</Subscript>(Piv)<Subscript>2</Subscript>]<Subscript>∞</Subscript>

A method for the synthesis of potassium pivalates (trimethylacetates) from potassium tert-butoxide and pivalic acid was proposed. The complexes of the formulas [K(H₂O)(Piv)]_∞(I) and [K₂(Phen)(H₂O)₂(Piv)₂]_∞ (II) (Piv denotes the pivalate anion and Phen denotes 1,10-phenanthroline) were obtained and characterized by elemental analysis and IR and ¹H NMR spectroscopy. The crystal structures of complexes I and II were determined using X-ray diffraction. Crystal structure I has a layered motif with two nonequivalent K atoms (C.N.s 5 + 2 and 6). The coordination of phenanthroline in II gives rise to a ribbon motif, the structure containing three nonequivalent K atoms (C.N.s 6, 6 + 1, and 8).     

Synthesis and study of uranyl arsenate (UO<Subscript>2</Subscript>)<Subscript>3</Subscript>(AsO<Subscript>4</Subscript>)<Subscript>2</Subscript> · 12H<Subscript>2</Subscript>O

A method for producing synthetic troegerite of composition(UO₂)₃(AsO₄)₂ · 12H₂. Owas developed. X-ray diffraction, IR spectrometry, X-ray fluorescence analysis, and scanning calorimetry were used to study its dehydration and thermal decomposition, to solve the structgure, and to determine X-ray diffraction and IR spectroscopic characteristics.     

Hydrothermal synthesis and crystal structure of a novel nickel(II) complex: [Ni(H<Subscript>2</Subscript>Bibzim)<Subscript>3</Subscript>Cl<Subscript>2</Subscript> · 2H<Subscript>2</Subscript>O] (H<Subscript>2</Subscript>Bibzim = 2,2-Bibenzimidazole)

A novel organic-inorganic hybrid compound based on weak intermolecular interactions formulated as Ni(H₂Bibzim)₃Cl₂ · 2H₂O (H₂Bibzim = 2,2-bibenzimidazole, formula, C₁₄H₁₀N₄) has been synthesized under hydrothermal conditions and characterized by elemental analysis, single-crystal X-ray diffraction analyses, and IR spectra. It crystallizes in the orthorhombic system, space group Pbcn, Z = 2, a = 20.8530(19), b = 15.7838(14), c = 12.3159(11) Å, V = 4053.7(6) ų, M _r = 1736.84, ρ_c = 1.423g/cm³, λ = 0.71073 Å, μ(MoK _α) = 0.664 mm^?1, F(000) = 1792, R = 0.0283 and wR = 0.0707 for 3746 observed reflections with I > 2σ(I). The complex is composed of mononuclear cations [Ni(H₂Bibzim)₃]²⁺, chlorine anions, and lattice water molecules, which are linked into a two-dimensional supramolecular architectures via hydrogen bonds and π-π-stacking interactions.     

Synthesis and photocatalytic activity of mesoporous SiO<Subscript>2</Subscript>–TiO<Subscript>2</Subscript>

Mesoporous SiO₂–TiO₂ was synthesized by the sol–gel method using Si(OC₂H₅)₄, Ti(OC₂H₅)₄, and stearyltrimethylammonium chloride. By using acetylacetone as the capping agent of Ti(OC₂H₅)₄, homogeneous SiO₂–TiO₂ composite was obtained. Spherical mesoporous SiO₂–TiO₂ was also synthesized by the sol–gel method using W/O emulsion under microwave irradiation. The specific surface area of these mesoporous SiO₂–TiO₂ materials decreased when the Ti/Si molar ratio was higher than 0.1, which indicated that Ti was homogeneously distributed in mesoporous SiO₂ matrix at Ti/Si ≦ 0.1. The photocatalytic activity of mesoporous SiO₂–TiO₂ materials was investigated by the degradation of methylene-blue in water under UV light irradiation. Mesoporous SiO₂–TiO₂ was effective for the adsorption–decomposition of methylene-blue.