Synthesis and characterization of ciprofloxacin compounds with cadmium(II) and mercury(II) chlorides

Five new compounds of ciprofloxacin (CfH = C₁₇H₁₈FN₃O₃) with cadmium(II) and mercury(II) chlorides were synthesized. The compounds were characterized by chemical analysis, powder X-ray diffraction, pH-metric titration, UV spectroscopy, and thermal analysis.     

LiNa2AlF6: a powder structure solution

Lithium sodium aluminium fluoride was obtained as a white powder by melting a stoichiometric mixture of AlF₃, NaF and LiF at 1223 K, and then cooling to 923 K and sintering at this temperature for 4 h. The ab initio crystal structure determination was carried out using X‐ray powder diffraction techniques. The monoclinic structure of LiNa₂AlF₆ can be related to cubic elpasolite. The Li and Al atoms lie on inversion centres. The main octahedral AlF₆ structural elements are not deformed, but are rotated slightly with respect to the unit‐cell axes. The Li atoms have octahedral coordinations, whereas the Na atoms have cubo‐octahedral coordinations. The Na coordination polyhedron is distorted in comparison with that of elpasolite.     

Study of the heat capacity of Lu2Cu2O5 in the temperature range 366–992 K

Experimental data on the molar heat capacity of Lu₂Cu₂O₅ in the temperature range 366–992 K have been obtained. The experimental data have been used to calculate the thermodynamic properties of the oxide compound.     

NaAlF4: Preparation, crystal structure and thermal stability

The compound NaAlF₄ has been obtained in the form of thin fibrous crystals or fine colorless powder by condensation at 18 °C of vapors arising over chiolite Na₅Al₃F₁₄ or NaCaAlF₆, heated up to 800 °C. Thermal stability has been investigated by the methods of thermal analysis and high temperature X-ray diffraction. When heated in air, NaAlF₄ is stable up to 390-400 °C, then there is an exothermal solid state decay into Na₅Al₃F₁₄(s) and AlF₃(s). At higher temperature Na₅Al₃F₁₄(s) decays into Na₃AlF₆(s) and NaAlF₄(g). The crystal structure (space group Cmcm, a=3.6124(1) Å, b=14.9469(7) Å, c=5.2617(3) Å, V=284.10 Å³) has been determined by X-ray powder diffraction method. In the crystal structure of NaAlF₄ the octahedrons [AlF₆] are joined through vertices and form corrugated layers, sodium ion layers being located between them. The distances between the atoms of Al-F are in the range 1.791-1.814 Å, and those for Na…F are in the range 2.297-2.439 Å. In spite of limited thermal stability of the crystal form, the compound NaAlF₄ is the main component of the gas mixture over solid and molten salts in the ternary system NaF-AlF₃-CaF₂ and participates in chemical transformations between the phases at high temperature.     

Structural Properties and State of a Zirconium Dioxide Surface Layer Modified with Mе3+ Cations

Russian Journal of Physical Chemistry A - The effect Ме3+ (Al, Y, Sc, Fe, and Mn) cations on the structural properties and state of a zirconium dioxide surface layer is investigated....     

CdBiO2Cl: synthesis and powder structure solution

The title compound, cadmium bismuth dioxide chloride, CdBiO₂Cl, was obtained as a white powder by reaction of solid BiOCl with CdO at 973 K. Ab initio crystal structure determination was carried out using X-ray powder diffraction techniques, including direct methods for atom location and Rietveld fitting for the final refinement. Being monoclinic, the crystal structure can be related to tetragonal Sillen layered phases. The main structural elements present are CdBiO₂⁺ pleated metal–oxy­gen layers alternating with Cl layers along the c axis, whereas along the b axis, all atoms are on mirror planes. The formation of a strong Cd—Cl bond draws the layers together, causing layer deformation and a monoclinic distortion in the layer arrangement.     

Study of the adsorption of sulfur dioxide on dealuminated zeolites Y by thermal desorption and powder X-ray diffraction

Sulfur dioxide is adsorbed on zeolites Y in two forms. The amount of the stable form (T_des=350–390 K) changes in proportion to the sodium content in the zeolite The stable form is localized in a large void at a distance of 1.8 å from the S_II position and causes redistribution of sodium cations. The weakly bound form (T_des=286–300 K) makes the main contribution to the adsorption of SO₂ on highly siliceous zeolites Y and is formed by adsorbate-adsorbate interaction, and it is apparently delocalized in a large void. Out-of-framework aluminum compounds that are formed during dealumination decrease the free volume of the zeolite without changing the nature of interaction of SO₂ with the zeolite.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 535–541, March, 1991.     

Nature and centers of localization of extraframework particles in Y zeolite dealuminated by silicon tetrachloride

X-ray diffraction, XPS, and NMR have been used to investigate the nature and centers of localization of nonframework particles in Y zeolite dealuminated by silicon tetrachloride. It has been established that the reaction products formed upon dealumination consist mainly of aluminum compounds that migrate from the volume of the zeolite to the surface and are also partially localized in internal supercages and small cages (sodalite cells). Water washing removes the particles localized in the supercages but does not affect the particles localized in sodalite cells. It has been shown that, by plotting maps of electron density on the basis of x-ray powder diffraction patterns, the sites of localization of extraframework particles can be determined. The results are consistent with those obtained by other methods, and the maps of electron density give a graphic picture of changes in internal structure of the Y zeolite.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1729–1734, August, 1989.The authors wish to express their appreciation to V. M. Mastikhin for assistance in taking the²⁷Al and²⁹Si NMR spectra.     

Nanocomposite proton conductors containing mesoporous oxides as the promising fuel cell membranes

Composite proton-conducting electrolytes are synthesized based on H₄SiW₁₂O₄₀ · xH₂O, CsHSO₄, (CsH₂PO₄)_0.9(CsHSO₄)_0.1 and mesoporous matrices SBA-15 and MCM-41 and their transport and structural characteristics are studied. Composites based on silicotungstic acid demonstrate the conductivity from ～10^?3 to 10^?4 S/cm in the temperature range of 25–140°C at the increased partial pressure of water vapor. The conductivity of systems CsHSO₄-SBA-15 (at T = 140–200°C) and (CsH₂PO₄)_0.9(CsHSO₄)_0.1-SBA-15 (at T = 200–230°C) reaches 10^?2 S/cm and is independent of humidity. The electrolytes studied are promising as proton-exchange membranes of fuel cells operating at low and medium temperatures.