catena‐Poly[[aqua­barium(II)]‐μ‐aqua‐bis­(μ‐2′‐carboxy­biphenyl‐2‐carboxyl­ato)]

In the title compound, [Ba{HOOC(C₆H₄)₂CO₂}₂(H₂O)₂] or [Ba(C₁₄H₉O₄)₂(H₂O)₂], the Ba atoms are coordinated by nine O atoms, six from two 2′‐carboxy­biphenyl‐2‐carboxyl­ate (Hbpdc⁻) ligands and three from three coordinated water mol­ecules, resulting in the formation of face‐sharing distorted monocapped square anti­prisms. The Hbpdc⁻ ligands bridge the Ba atoms to form a one‐dimensional helical polymer, with a Ba⋯Ba distance across the chain of 4.1386 (17) Å. Adjacent chains are parallel to each other. The two independent ligands are tetra­dentate and have the same coordination mode, exhibiting μ‐oxo bridges and η⁸‐chelation. The crystal structure is further stabilized by hydrogen bonds within each chain.     

The first suberate lanthanum(III) complex without uncoordinated water

catena‐Poly­[[aqua­lanthanum(III)]‐μ‐(8‐carboxy­octanoato)‐μ‐octanedioato], [La(C₈H₁₂O₄)(C₈H₁₃O₄)(H₂O)]_n, is, to our knowledge, the first reported rare‐earth complex containing a flexible long‐chain ligand that crystallizes without water of crystallization. The layered polymeric structure is built from infinite chains of one‐edge‐sharing LaO₈(H₂O) polyhedra, connected through the carbon backbone chains of the ligands. The two chemically different ligands act in the same coordination modes, exhibiting chelating bonds and μ‐1,1‐bridging monodentate linkage, and adopting the same extended conformation. In the relatively limited hydrogen‐bonding network, a very strong hydrogen bond between the deprotonated and protonated ligand ends stabilizes the framework.     

AC-Conductivity and proton transport number of BaZr0.90Al0.10O3-δ

AC-conductivity measurements of BaZr_0.90Al_0.10O_3−δ (where δ describes the number of oxygen ion vacancies per unit cell) in wet and dry N₂ have been carried out over the temperature range from 400 to 900 °C. Both atmospheres showed the usual Arrhenius behavior of BaZr_0.90Al_0.10O_2.95. The proton transport number,t _H, was also determined from the conductivity measurements of BaZr_0.90Al_0.10O_2.95 in wet and dry N₂ and takes up values of 0.97 and 0.78 in the temperature range 400 – 900 °C, respectively.     

Polymeric tetra­aqua­tris­(malonato)­dilanthanum(III) monohydrate

The title compound, [La₂(C₃H₂O₄)₃(H₂O)₄]·H₂O, forms a layer‐type polymeric structure. The layers, which contain infinite puckered four‐membered La—O—La—O rings in a pseudo‐ternary symmetry, are formed by the lanthanum and one independent malonate group. They are interconnected by the second independent malonate group, giving a three‐dimensional framework in which wide channels accommodate one disordered water mol­ecule of crystallization. The La atom lies on a twofold axis and is ten‐coordinated by eight O atoms from carboxyl­ate groups and two water mol­ecules. One malonate group is monodentate and triply bridging chelating, whilst the other is doubly monodentate. The extensive network of hydrogen bonds and bridge bonds observed in this structure enhances the structural stability. Despite some identical subfeatures, this structure is quite different from that observed in [La₂(C₃H₂O₄)₃(H₂O)₃]·2H₂O.     

Poly[tetra­aquadi‐μ3‐malonato‐cobalt(II)­calcium(II)]

The structure of the polymeric title compound, [CaCo(C₃H₂O₄)₂(H₂O)₄]_n, consists of CaO₈ and CoO₆ polyhedra linked together by malonate groups. The Co atom lies on a centre of symmetry in an octa­hedral arrangement, and is coordinated by four malonate O atoms in a planar arrangement and two water mol­ecules in a trans conformation. The geometry around the Ca atom, which lies on a twofold axis, may be described as a distorted square anti­prism, which involves two water mol­ecules and six malonate O atoms. The Co—O and Ca—O bond lengths are in the ranges 2.0711 (12)–2.1004 (14) and 2.3775 (12)–2.6329 (12) Å, respectively.     

Synthesis and crystal structure of anhydrous copper suberate: [Cu<Subscript>2</Subscript>(OOC-(CH<Subscript>2</Subscript>)<Subscript>6</Subscript> -COO)<Subscript>2</Subscript>]

The title compound [Cu₂(OOC-(CH₂)₆-COO)₂] was synthesized and its crystal structure has been determined by single crystal X-ray diffraction methods. The complex crystallizes in the triclinic space group P-1 with a=5.1077(5) ?, b=8.362(2) ?, c=11.378(2) ?, α=93.773(6)°, β=97.587(9)°, γ=90.493(’9)° and D _cal=1.629 mg/m³ for Z=1.  The structure is polymeric and consists of discrete anhydrous centrosymmetric binuclear units [Cu₂(OOC-(CH₂)₆-COO)₂]. The two copper(II) centres bridged by the suberate groups in a syn-syn conformation, are in pentacoordinated distorted square-pyramidal coordination environment, with an intramolecular Cu–Cu distance of 2.5793(10) ?. Each binuclear unit, related to the next through μ_oxo bridges with a Cuμ_oxo–Cuμ_oxo separation of 3.2326(10)?, defines infinite chains of one-edge sharing CuO₅ square pyramid.     

Polymeric aqua­(glutarato)(hydrogen glutarato)­lanthanum(III) monohydrate

The structure of the title compound, [La(C₅H₆O₄)(C₅H₇O₄)‐(H₂O)]·H₂O, consists of dense layers formed by chains of one‐edge‐sharing LaO₉(H₂O) polyhedra, linked together by the glutarate ligand. The three‐dimensional polymeric structure, built up through connection of these layers by the hydrogen glutarate ligand, exhibits cavities accommodating a guest water mol­ecule. The lanthanum ion is tenfold coordinated by four glutarates, acting as bridging–chelating carboxyl­ate groups, by three hydrogen glutarates, three times monodentate, and by one water mol­ecule. Its coordination polyhedron is highly distorted and intermediate between a bicapped dodecahedron and a tetracapped trigonal prism. Hydro­gen bonding links the two water mol­ecules and the framework built up from this polynuclear coordination polymer. A very short hydrogen bond, D?A = 2.484 (3) Å, links the proton­ated with the deprotonated acid groups in the hydrogen glutarate.     

Poly[diaquadi‐μ6‐oxalato‐μ5‐oxalato‐chromium(III)rubidium(I)]: a new supramolecular isomer

The title compound, [CrRb(C₂O₄)₂(H₂O)₂]_n, obtained under hydrothermal conditions and investigated structurally at 100 K, is a three‐dimensional supramolecular isomer of the layered structure compound studied at room temperature. This novel polymer is built up from crosslinked heterobimetallic units. The linkage of alternating edge‐ and vertex‐shared RbO₇(H₂O)₂ and CrO₄(H₂O)₂ polyhedra running along three different directions gives a dense packing. The two independent ligands display two η⁴‐chelation modes and two conventional carboxylate bridges. However, the pentadentate ligand connects the Cr^III and Rb^I ions through one O‐atom bridge, while the hexadentate ligand exhibits an additional η³‐chelation and two O‐atom bridges. Each coordinated water molecule forms an O‐atom bridge between the two metals. Moreover, in the absence of protonated ligands, these water molecules act as donors through their four H atoms in strong‐to‐weak hydrogen bonds. This results in zigzag chains of alternating oxalate and aqua ligands parallel to the twofold screw axis. The six double oxalates known to date containing an alkali and Cr^III all present layered two‐dimensional structures. In the series, this supramolecular isomer is the first three‐dimensional framework.     

Phase transition in the ternary fluorides Li3Alf6 and Li3CrF6

The phase transitions of two ternary fluorides have been reinvestigated by thermal and X-ray diffraction analyses. Four phase transitions have been detected at T ₁ = 483 ± 5 K, T ₂ = 548 ± 5 K, T ₃ = 765 ± 5 K and T ₄ = 867 ± 5 K for Li₃AlF₆. Only two transformations occurred at T ₁ = 550 ± 5 K and T ₂ = 660 ± 10 K for Li₃CrF₆. Dielectric and optical measurements performed respectively on ceramics and single crystals revealed a ferroelectric behaviour coupling partially with ferroelastic coupling for the two investigated fluorides.     

Numerical Investigation of Quasi-Lamb Modes in C‑Tilted ZnO/SiC Composite Membrane for High Performance Pressure Micro-Sensor

Acoustical Physics - Using the finite element method, we have studied the Lamb modes characteristics propagation in c?tilted ZnO/SiC thin film composite membrane. Phase velocity dispersion...