Treatment of gibbsite {γ-Al(OH)3} with the lithium salts LiX {X = Cl, Br, NO3} in water leads to intercalation of both the cations and anions into the host structure to give [LiAl2(OH)6]X·H2O {X = Cl, Br, NO3}. Thermogravimetric analysis indicates that these materials can be readily dehydrated to give highly hydroscopic, crystalline layered phases [LiAl2(OH)6]X {X = Cl, Br, NO3}. The structures of these dehydrated phases have been determined by synchrotron X-ray and neutron powder diffraction. The dehydrated intercalates with {X = Cl, Br} are isomorphous and crystallize in the P63/mcm space group. [LiAl2(OH)6]NO3 adopts a similar structure but crystallizes in space group P63/m due to disorder of the intercalated nitrate anions in the crystallographic ab plane. All the intercalates consist of eclipsed Al(OH)3 layers stacked along the c-axis with the halide or nitrate ions located at the cell edges and midway between the Al(OH)3 layers. The lithium ions have been located in the unfilled octahedral sites within the Al(OH)3 layers. The structure of the hydrated phase [LiAl2(OH)6]Cl·H2O has also been determined, it adopts a similar structure with eclipsed [LiAl2(OH)6]+ layers stacking along the c-axis. However the intercalated Cl- ions and water molecules were found to be disordered over five sites located midway between the Al(OH)3 layers.

Bi2ZnTiO6, a lead-free analogue of PbTiO3, has been prepared by high-pressure solid-state synthesis methods. Structural analysis reveals that the tetragonal distortion (c/a ratio = 1.21) of Bi2ZnTiO6 is the largest reported for any d0 B site Pb or Bi based perovskite. Significant cation displacements result in a point-charge calculated polarization of 150 μC cm-2.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The dicarboxylate anions 1,4-benzenedicarboxylate and fumarate can be selectively intercalated into the layered double hydroxide [LiAl 2 (OH) 6 ]Cl‚H 2 O from equimolar molar mixtures of the 1,2-, 1,3-, and 1,4-benzenedicarboxylate and fumarate and maleate isomers, respectively. Time-resolved in situ energy-dispersive X-ray diffraction studies have shown that these are the thermodynamic products following the conversion of an initial phase in which all the anions are simultaneously intercalated.

A family of layered lanthanide hydroxyhalide intercalation hosts, Ln2(OH)5X·1.5H2O (X = Cl, Br; Ln = Y, Dy, Er, Yb), has been synthesized under hydrothermal conditions and their crystal structure determined. These are the first structures for the m = 1 members of the Ln2(OH)6−m (A) m ·nH2O family of intercalation hosts to be determined. Reaction mixtures with Ln = Yb always yield a biphasic product which adopts an orthorhombic or monoclinic crystal structure. In both cases the layer composition is [Yb2(OH)5(H2O)1.5]+ and the Yb is eight or nine coordinated to bridging hydroxide anions and coordinated water molecules. Charge balancing halide anions are located in the interlayer gallery. The orthorhombic structure is adopted by the other chloride host lattices and the monoclinic one by Y2(OH)5Br·1.5H2O. These materials have been shown to undergo facile room temperature anion exchange reactions with a range of organic dicarboxylates.

The hydrothermal synthesis of the large-pore oxy-fluorinated gallophosphate ULM-5 has been followed in situ using time-resolved energy dispersive and angular dispersive X-ray diffraction. A variety of synthetic parameters such as temperature, reagent stoichiometry, source materials, and pH have been studied, and their effect on the crystallization determined. The nature of the phosphorus source used, either orthophosphoric acid or phosphorus pentoxide, is found to have a profound influence on the reaction pathway. Using orthophosphoric acid, ULM-5 is found to form very rapidly following a short induction period. A kinetic analysis of the crystallization of ULM-5 using orthophosphoric acid under isothermal hydrothermal conditions has been performed. Comparison of the experimentally determined extent of reaction (α) versus time data with those predicted by various theoretical models indicates that over a wide range of temperatures and pH the crystallization can be modeled by a three-dimensional diffusion-controlled process. This process occurs at a rate essentially independent of temperature and pH. In contrast, using phosphorus pentoxide, the formation of ULM-5 is found to proceed via the formation of either of two distinct crystalline intermediate phases, which subsequently react to form the ULM-5 final product at a rate which is strongly dependent on temperature. The relative quantities of each intermediate phase formed depend critically on the precise reagent stoichiometry used. Conditions have been identified in which ULM-5 can be formed exclusively via either intermediate phase. The mechanism of transformation of intermediate to product phases appears to be either a direct solid−solid transformation, or via the dissolution or amorphorization of only a small quantity of material at the surface of the intermediate crystallites.

Time-resolved in situ energy-dispersive X-ray diffraction studies on the intercalation of dicarboxylate anions

Optical Absorption and Photoluminescence (PL) Measurements: The LiPBO sample was prepared as a thin film on a quartz substrate by thermal evaporation at a rate of 0.2 /s at 5´10 ±6 torr. Optical absorption and PL spectra were measured by UV-vis spectrometry and IAE-PL-SYS-1 (Nanotech) equipped with a linear charge coupled device detector (Ocean Optics, S2000) and a Xenon lamp coupled with a monochromator. For the PL measurements, the excitation wavelength was fixed as 365 nm, with regard to the absorption spectrum.Fabrication and Characteristics of OELD: A 1:1 mixture of poly(ether imide) (PEI) and N,N¢-diphenyl-N,N¢-bis(3-methylphenyl)-[1,1¢-diphenyl]-4,4¢-diamine (TPD) were dissolved in chloroform to form a solution concentration of ca. 0.5 wt.-%. The solution was spun for ca. 1.5 min at 5000 rpm onto ITO glass, which had a seven-segment pattern on it, and subsequently dried at 110 C for ca. 1 h. The dried polyimide HTL film had a thickness of 375 as determined by a surface profiler (Tencor P-10). Next, LiPBO was thermally evaporated onto the polyimide HTL using a low-temperature effusion cell (EPI-30-M-LT). The evaporation rate, the temperature, the vacuum, and the film thickness were ca. 0.1 /s, 315 C, 5´10 ±6 torr, and 200 , respectively. A 3500 thick layer of Aluminum was deposited on the LiP-BO thin film by thermal evaporation at a rate of up to 5 /s. The evaporation rate and thickness were detected using a thickness monitor (Sycon Instruments STM-100/MF). The luminance±current density±voltage (L±J±V) characteristics of OELD were measured by IAE-OELD-SYS with an electrometer (Keithley 237), a calibrated photodiode, a diode array rapid scan analyzer (PSI DARSA-2000), and a candela meter (Minolta CS1000). The electroluminescent (EL) spectra were measured by a spectrophotometer (JOBIN-YVON-SPEX 270M) with a photomultiplier tube (PMT) as a detector and the IAE-PL-SYS-1 mentioned previously.The design of porous solids that can selectively and reversibly bind molecules has been the subject of much recent interest. [1] These highly specific interactions are critical in a range of important practical chemical technologies such as chemical sensing, [2±4] separations, [5] and catalysis [6] . The design of lamellar inorganic hosts such as clays, phosphates, phosphonates and modified thin films that exhibit molecular recognition features has recently been reviewed by Mallouk and Gavin. [7] In lamellar inorganic solids, guest molecules access intracrystalline binding sites via intercalation reactions. In most cases, inorganic intercalation reactions are unselective processes which are driven by either oxidation±reduction, ion-exchange, acid±base, or donor±acceptor reactions. The interlamellar gallery expands to accommodate the guest species resulting in little size-or shape-selectivity to the reaction. Here we report the use of a crystalline-ordered layered double hydroxide (LDH) that exhibits shape-selective intercalation. In addition, we have found that this remarkable shape selectivity can be controlled by alterin...