Flux synthesis of (3,4)-connected zinc phosphites with different framework topologies

Two three-dimensional open-framework zinc phosphites, H₂aem·Zn₃(HPO₃)₄·0.5H₂O (1) and H₂apm·Zn₃(HPO₃)₄ (2), have been synthesized by a phosphorous acid flux method, where aem=4-(2-aminoethyl)morpholine and apm=4-(3-aminopropyl)morpholine. Compound 1 crystallizes in the monoclinic system, P2₁/c, a=9.5852(7) Å, b=20.3941(8) Å, c=10.5339(8) Å, β=94.125(9)°, V=2053.8(2) Å³, Z=4, R₁=0.0319, wR₂=0.0628. Compound 2 crystallizes in the monoclinic system, P2₁/n, a=8.589(2) Å, b=14.020(3) Å, c=16.606(3) Å, β=97.190(8)°, V=1983.9(7) Å³, Z=4, R₁=0.0692, wR₂=0.1479. Both compounds are based on (3,4)-connected networks with 8- and 12-ring channels, which are constructed from Zn₃(HPO₃)₄ clusters as the same secondary building units. These inorganic clusters are spatially organized by different structure-directing agents into different three-dimensional frameworks.     

Crystal chemistry of three new monodimensional fluorometalates templated with ethylenediamine

Three new monodimensional hybrid metal (Ti, In, Al) fluorides are synthesized with ethylenediamine (en) as a templating agent in solvothermal conditions assisted by microwave heating. All structures involve inorganic chains built up from TiO₂F₄ octahedra connected by two opposite O²⁻ vertices in [H₂en]·(TiOF₄) (I), from InF₆(H₂O) pentagonal bipyramids linked by F–F edges in [H₂en]·(InF₄(H₂O))₂·H₂O (II) and from (Al₇F₃₀)⁹⁻ polyanions sharing two opposite AlF₆ octahedra in [H₂en]₃·(Al₆F₂₄) (III). I is tetragonal, P4/ncc, a = 12.761(3) Å, c = 8.041(3) Å; II is orthorhombic, F2dd, a = 6.904(5) Å, b = 16.559(5) Å, c = 19.777(4) Å and III is monoclinic, P2₁/n, a = 9.387(2) Å, b = 6.710(2) Å, c = 21.513(6) Å, β = 97.18(3)°.     

Syntheses, crystal structures and spectroscopic properties of KEu[AsS4], K3Dy[AsS4]2 and Rb4Nd0.67[AsS4]2

Three rare earth compounds, KEu[AsS₄] (1), K₃Dy[AsS₄]₂ (2), and Rb₄Nd_0.67[AsS₄]₂ (3) have been synthesized employing the molten flux method. The reactions of A₂S₃ (A = K, Rb), Ln (Ln = Eu, Dy, Nd), As₂S₃, S were accomplished at 600 °C for 96 h in evacuated fused silica ampoules. Crystal data for these compounds are: 1, monoclinic, space group P2₁/m (no. 11), a = 6.7276(7) Å, b = 6.7190(5) Å, c = 8.6947(9) Å, β = 107.287(12)°, Z = 2; 2, monoclinic, space group C2/c (no. 15), a = 10.3381(7) Å, b = 18.7439(12) Å, c = 8.8185(6) Å, β = 117.060(7)°, Z = 4; 3, orthorhombic, space group Ibam (no. 72), a = 18.7333(15) Å, b = 9.1461(5) Å, c = 10.2060(6) Å, Z = 4. 1 is a two-dimensional structure with ²_∞[Eu(AsS₄)]⁻ layers separated by potassium cations. Within each layer, distorted bicapped trigonal [EuS₈] prisms are linked through distorted [AsS₄]³⁻ tetrahedra. Each Eu²⁺ cation is coordinated by two [AsS₄]³⁻ units by edge-sharing and bonded to further two [AsS₄]³⁻ units by corner-sharing. Compound 2 contains a one-dimensional structure with ¹_∞[Dy(AsS₄)₂]³⁻ chains separated by potassium cations. Within each chain, distorted bicapped trigonal prisms of [DyS₈] are linked by slightly distorted [AsS₄]³⁻ tetrahedra. Each Dy³⁺ ion is surrounded by four [AsS₄]³⁻ moieties in an edge-sharing fashion. For compound 3 also a one-dimensional structure with ¹_∞[Nd₀.₆₇(AsS₄)₂]⁴⁻ chains is observed. But the Nd position is only partially occupied and overall every third Nd atom is missing along the chain. This cuts the infinite chains into short dimers containing two bridging [As₄]³⁻ units and four terminal [AsS₄]³⁻ groups. 1 is characterized with UV/vis diffuse reflectance spectroscopy, IR, and Raman spectra.     

Self-assembly of two novel bisupporting Keggin-polyoxometalate derivatives: Hydrothermal synthesis and structure characterization of (X = P, m = 1; X = Si, m = 2)

Two novel organic–inorganic hybrid polyoxometalates, (X = P, m = 1 1; X = Si, m = 2 2; 2,2′-bpy = 2,2′-bpyridine), have been synthesized under hydrothermal conditions and structurally characterized by single-crystal X-ray diffraction. They are isostructural, possessing orthorhombic, and the parameters of unit cells for compound 1 are space group Pbca, a = 17.317(4) Å, b = 17.092(3) Å, c = 20.587(4) Å, V = 6445(2) Å³, Z = 4; for compound 2 are space group Pcab, a = 17.181(3) Å, b = 18.198(4) Å, c = 20.672(4) Å, V = 6463(2) Å³, Z = 4. The two compounds show a layer framework constructed from Keggin-polyoxoanion clusters and [Cu (2, 2′-bpy)₂]²⁺ coordination polymer fragments via weak covalent interactions, resulting in a 3D network via supramolecular interactions. Their electrochemical properties are studied in detail.     

(C6H16N2)Zn3(HPO3)4H2O: a new layered zinc phosphite templated by diprotonated trans-1,4-diaminocyclohexane

Employing trans-1,4-diaminocyclohexane (trans-1,4-DACH) as a template, a new two-dimensional layered zinc phosphite (C₆H₁₆N₂)Zn₃(HPO₃)₄H₂O (1) has been prepared hydrothermally. Single-crystal X-ray diffraction analysis shows that it crystallizes in the monoclinic space group P2₁/n with a=10.458(2) Å, b=14.720(3) Å, c=13.079(3) Å, β=97.93(3)°, V=1994.1(7) ų, Z=4, R₁=0.0349 (I>2σ(I)) and wR₂=0.0605 (all data). The inorganic layer is built up by alternation of ZnO₄ tetrahedra and HPO₃ pseudo pyramids forming a 4.6.8-net. The sheet is featured by a series of capped six-membered rings. The diprotonated trans-1,4-DACH molecules reside in the interlayer region and interact with the inorganic network through H-bonds.     

Molybdenum(VI) network polymers based on anion–π interaction and hydrogen bonding: Synthesis, crystal structures and oxidation catalytic application

A crystallographic investigation of anion–π interactions and hydrogen bonds on the preferred structural motifs of molybdenum(VI) complexes has been carried out. Two molybdenum(VI) network polymers MoO₂F₄·(Hinca)₂ (1) and MoO₂F₃(H₂O)·(Hinpa) (2), where inca = isonicotinamide and inpa = isonipecotamide, have been synthesized, crystallographically characterized and successfully applied to alcohol oxidation reaction. Complex 1 crystallizes in the monoclinic space C2/c: a = 16.832(3) Å, b = 8.8189(15) Å, c = 12.568(2) Å, β = 118.929(3)°, V = 1560.1(5) Å³, Z = 4. Complex 2 crystallizes in the triclinic space P-1: a = 5.459(2) Å, b = 9.189(4) Å, c = 12.204(5) Å, α = 71.341(6)°, β = 81.712(7)°, γ = 77.705(7)°, V = 564.8(4) Å³, Z = 2. Complex 1 consists of hydrogen bonding and anion–π interactions, both of which are considered as important factors for controlling the geometric features and packing characteristics of the crystal structure. The geometry of the sandwich complex of [MoO₂F₄]²⁻ with two pyridine rings indicates that the anion–π interaction is an additive and provides a base for the design and synthesis of new complexes. For complex 2, the anions and the protonated inpa ligands form a 2D supramolecular network by four different types of hydrogen contacts (N–HF, N–HO, O–HF and O–HO). The catalytic ability of complexes 1 and 2 has also been evaluated by applying them to the oxidation of benzyl alcohol with TBHP as oxidant.     

Synthesis and crystal structure analysis of Sr8Cu3In4N5 and Sr0.53Ba0.47CuN

Single crystals of new quaternary compounds Sr₈Cu₃In₄N₅ and Sr_0.53Ba_0.47CuN were prepared, respectively, from a Sr–Cu–In–Na melt under 7 MPa of N₂ and from a Sr–Ba–Cu–In–Na melt under 0.5 MPa of N₂ by slow cooling from 1023 to 823 K. The crystal structures were determined by single-crystal X-ray diffraction. Sr₈Cu₃In₄N₅ has an orthorhombic structure (space group, Immm, Z=2, a=3.8161(5) Å, b=12.437(2) Å, c=18.902(2) Å), and is isostructural with Ba₈Cu₃In₄N₅. It contains nitridocuprates of isolated units ⁰[CuN₂] and one-dimensional linear chains _∝¹[CuN_2/2] and one-dimensional indium clusters _∝¹[In₂In_2/2]. Sr_0.53Ba_0.47CuN crystallizes in an orthorhombic cell, space group Pbcm, Z=4, a=5.4763(7) Å, b=9.2274(12) Å, c=9.0772(12) Å. The structure contains infinite zig-zag chains _∝¹[CuN_2/2] which kink at every second nitrogen atom.     

Syntheses and characterization of Co(pydc)(H2O)2 and Ni(pydc)(H2O) (pydc = 3,5-pyridinedicarboxylate)

The hydrothermal reaction of 3,5-pyridinedicarboxylic acid (pydcH₂) and Co(NO₃)₂ or Ni(NO₃)₂ in the presence of 4,4′-bipyridine results in two novel compounds Co(pydc)(H₂O)₂ (1) and Ni(pydc)(H₂O) (2). Crystal data: 1, monoclinic, C2/c, a=9.900(2), b=11.984(2), c=7.3748(15) Å, β=105.37(3)°, V=843.7(3) Å³, Z=4; 2, monoclinic, P2₁/c, a=7.7496(6), b=15.0496(11), c=6.4224(5) Å, β=108.437(1)°, V=710.59(9) Å³, Z=4. The structure of 1 is composed of honeycomb layers built up from {CoO₄N} trigonal bipyramids and 3,5-pyridinedicarboxylate bridges. The structure of 2 adopts a three-dimensional framework structure in which the Ni atoms are coordinated by the pydc bridges both within the honeycomb layer and between the layers. The magnetic properties of 1 and 2 have been investigated.     

Isolation of p-tricyanovinylphenyldicyanomethide ion via a [2+2] cycloaddition of 7,7,8,8-tetracyanoquinodimethane (TCNQ) molecules

In the presence of CoCl₂·6H₂O and dppm (bis(diphenylphosphino) methane), the reaction of TCNQ (7,7,8,8-tetracyanoquinodimethane) molecules by [2+2] cycloaddition forms a p-tricyanovinylphenyldicyanomethide ion (PCQ⁻), which has been obtained as one anion unit in one new compound [Co(dppmdo)₃][PCQ⁻]₂·H₂O 1 (dppmdo = bis(diphylphospine oxide) methane). Its structure was determined by X-ray crystallography: 1 crystallizes in with a = 14.174(3) Å, b = 19.553(4) Å, c = 19.776(4) Å, α = 112.72(3)°, β = 95.43(3)°, γ = 110.79(3)°, and Z = 2. It was characterized by IR spectra, UV–Vis spectra, and cyclic voltammogram. Magnetic properties indicate that no magnetic coupling between PCQ⁻ and [Co(dppmdo)₃]²⁺ unit.     

Comparative evolved gas analytical and structural study on trans-diammine-bis(nitrito)-palladium(II) and platinum(II) by TG/DTA–MS, TG–FTIR, and single crystal X-ray diffraction

Detailed study on identification and thermal decomposition of solid title compounds 1 and 2 crystallized from the used aqueous ammonia solutions of Pd(NH₃)₂(NO₂)₂ and Pt(NH₃)₂(NO₂)₂, has been carried out. Beyond the composition of complexes 1 and 2, their trans square planar configuration have already been recognized by reference IR spectra and powder XRD patterns, nevertheless their exact molecular and crystal structure as of trans-Pd(NH₃)₂(NO₂)₂ (1, Pd-NN) and trans-Pt(NH₃)₂(NO₂)₂ (2, Pt-NN) has been determined by single crystal X-ray diffraction (R = 0.0515 and 0.0341), respectively. Despite their compositional and configuration analogy, they crystallize in different crystal systems and space groups. The crystals of 1 (Pd-NN) are triclinic (space group No. 2, P-1, a = 5.003(1) Å, b = 5.419(1) Å, c = 6.317(1) Å, α = 91.34(2)°, β = 111.890(10)°, γ = 100.380(10)°), while those of 2 (Pt-NN) are monoclinic (space group No. 5, C2, a = 7.4235(16) Å, b = 9.130(2) Å, c = 4.4847(10) Å, β = 99.405(7)°).The pyrolytic processes of 1 and 2 (which might be sensitive to shock and heat) have been followed by simultaneous thermogravimetric and differential thermal analysis (TG/DTA), while the evolved gaseous species have been traced in situ by online coupled TG/DTA–EGA–MS and TG–EGA–FTIR instruments in He and air. Pd and Pt powders, forming as final solid products in single step, are captured and checked by TG and XRD. Whilst the unified evolved gas analyses report evolution of N₂, H₂O, NH₃, N₂O, NO, and NO₂ gases as gaseous product components in the exothermic decomposition of both trans-Pd(NH₃)₂(NO₂)₂ (1) and trans-Pt(NH₃)₂(NO₂)₂ (2) starting from ca. 230 and 220 °C, in sealed crucibles with a pinhole on the top, respectively.     

Novel M(II)–Hg(II) coordination polymers generated from metal-containing building blocks M(2-pyrazinecarboxylate)2 · (H2O)2 (M=Cu, Ni, Co) and HgCl2

A new class of M(II)–Hg(II) (M=Cu(II), Co(II), Ni(II)) mixed-metal coordination polymers, Cu(2-pyrazinecarboxylate)₂HgCl₂ (4), [Co(2-pyrazinecarboxylate)₂(HgCl₂)₂] · 0.61H₂O (5) and [Ni(2-pyrazinecarboxylate)₂(HgCl₂)₂] · 0.77H₂O (6), have been prepared by self assembly of metal-containing building blocks, M(2-pyrazinecarboxylate)₂ · (H₂O)₂(M=Cu(II), Co(II), Ni(II)), with HgCl₂. Compounds 4–6 were characterized fully by IR, elemental analysis and single crystal X-ray diffraction. Compound 4 crystallized in the monoclinic space group C2/c, with a=17.916(5) Å, b=7.223(2) Å, c=13.335(4) Å, β=128.726(3)°, V=1346.2(6) ų, Z=4. It contains alternating Hg(II) and Cu(II) metal centers that are cross-linked by 2-pyrazinecarboxylate spacers and chlorine co-ligands to generate a unique three-dimensional Hg(II)–Cu(II) mixed metal framework. Compound 5 crystallized in the triclinic space group P , with a=6.3879(7) Å, b=6.6626(8) Å, c=13.2286(15) Å, α=96.339(2)°, β=91.590(2)°, γ=113.462(2)°, V=511.71(10) ų, Z=1. Compound 6 also crystallized in the triclinic space group P , with a=6.3543(8) Å, b=6.6194(8) Å, c=13.2801(16) Å, α=96.449(2)°, β=92.263(2)°, γ=113.541(2)°, V=506.67(11) ų, Z=1. Compounds 5 and 6 are isostructural and in the solid state the Hg(II)M(II)Hg(II) units are connected by Hg₂Cl₂ linkages to produce a novel M(II)–Hg(II) (M=Co(II), Ni(II)) zigzag mixed-metal chain, in which a new type of M–M′–M′–M array was observed. The metal containing building blocks, M(2-pyrazinecarboxylate)₂ · (H₂O)₂ (M=Cu(II), Co(II), Ni(II)), exhibit different connectivities to HgCl₂ depending on the metal cation contained within them.     

DNA binding and oxidative cleavage activity of ternary (l-proline)copper(II) complexes of heterocyclic bases

Ternary copper(II) complexes [Cu(l-pro)(B)(H₂O)](NO₃) (1, 2) where l-pro = l-proline, B is a N,N-donor heterocyclic base, viz. 2,2′-bipyridine (bpy, 1), 1,10-phenanthroline (phen, 2), are synthesized, characterized, and their DNA binding and cleavage activity studied. The bpy complex (1) is structurally characterized by single-crystal X-ray crystallography. The complexes show the presence of a distorted square-pyramidal (4 + 1) CuN₃O₂ coordination geometry. Complex [Cu(l-pro)(bpy)(H₂O)](NO₃) (1) crystallizes in the triclinic space group P1 with unit cell parameters: a = 7.082(3) Å, b = 10.483(5) Å, c = 11.581(5) Å, α = 89.700(7)°, β = 83.488(8)°, γ = 84.109(8)° and V = 849.7(7) Å³. The one-electron paramagnetic complexes display a d–d band near 600 nm in water and show a cyclic voltammetric response due to Cu(II)/Cu(I) couple near 0.1 V (versus SCE) in Tris–HCl buffer–0.1 M KCl. Binding interactions of the complexes with calf thymus (CT) DNA have been investigated by emission, absorption, viscosity and DNA thermal denaturation studies. The phen complex displays significant binding propensity to the CT DNA giving an order: 2 (phen)  1 (bpy). The bpy complex does not show any apparent binding to the DNA and hence poor cleavage efficiency. Complex 2 shows efficient oxidative cleavage of SC-DNA in the presence of 3-mercaptopropionic acid (MPA) involving hydroxyl radical species as evidenced from the control data showing inhibition of DNA cleavage in the presence of DMSO and catalase.     

Preparation, crystal structure, vibrational spectra and thermal behavior of selenites of ethylene diamine, 1,3-propylene diamine and 1,4-butylene diamine

Selenites of ethylene diamine, propylene diamine and butylene diamine were prepared by crystallization from aqueous solution. The crystal structure was solved for all the substances. Ethylene diammonium(2+) selenite crystallizes in the orthorhombic space group P2₁2₁2, a=11.3710(2) Å, b=11.4390(5) Å, c= 4.6290(4) Å, V= 602.11(6) ų, Z=4, R=0.0341 for 5729 observed reflections. 1,3-Propylene diammonium(2+) selenite dihydrate crystallizes in the monoclinic space group C2/c, a=16.241(14) Å, b=6.673(5) Å, c=17.731(14) Å, β=110.88(2)°, V=1795(3) ų, Z=8, R=0.0271 for 12,233 observed reflections. 1,4-Butylene diammonium(2+) selenite dihydrate crystallizes in the monoclinic space group P2₁/c, a=6.686(5) Å, b=16.597(14) Å, c=9.282(8) Å, β=96.653(14)°, V=1023.2(14) ų, Z=4, R=0.0465 for 2918 observed reflections. The FTIR an FT Raman spectra of all the compounds were recorded and interpreted. The thermoanalytical properties were studied by the TG, DTG, and DTA methods in the 293–633 K temperature range. DSC measurements were carried out in the range from 98 K to the temperature of decomposition of the compounds. No thermal effect indicating a phase transition was observed in this temperature region.     

(1,4-dabH)2MnSnS4: The first thiostannate with integrated Mn ions in an anionic chain structure

The new thiostannate (1,4-dabH)₂MnSnS₄ (1,4-dab = 1,4-diaminobutane) was synthesized under solvothermal conditions. The compound crystallizes in the non-centrosymmetric space group Fdd2 with a = 22.8124(15) Å, b = 24.7887(16) Å, c = 6.4153(6) Å, Z = 8, and V = 3627.8(5) Å³. The structure consists of one-dimensional straight anionic chains composed of alternating SnS₄ and MnS₄ tetrahedra sharing common edges. The chains are directed along [001] and are surrounded by the organic cations which form undulated chains along [100] by strong intermolecular N–HN hydrogen bonding interactions. Several SH contacts suggest weak interactions between the anionic chains and the cations. The band gap amounts to 2.9 eV indicating that the compound is a photo-conductor. The compound is stable up to about 190 °C and decomposes in two distinct steps above this temperature.     

Synthesis, crystal structures, phase transition characterization and thermal decomposition of a new dabcodiium hexaaquairon(II) bis(sulfate): (C6H14N2)[Fe(H2O)6](SO4)2

The crystal structures of 1,4-diazabicyclo[2.2.2]octane (dabco)-templated iron sulfate, (C₆H₁₄N₂)[Fe(H₂O)₆](SO₄)₂, were determined at room temperature and at −173 °C from single-crystal X-ray diffraction. At 20 °C, it crystallises in the monoclinic symmetry, centrosymmetric space group P2₁/n, Z=2, a=7.964(5), b=9.100(5), c=12.065(5) Å, β=95.426(5)° and V=870.5(8) ų. The structure consists of [Fe(H₂O)₆]²⁺ and disordered (C₆H₁₄N₂)²⁺ cations and (SO₄)²⁻ anions connected together by an extensive three-dimensional H-bond network. The title compound undergoes a reversible phase transition of the first-order at −2.3 °C, characterized by DSC, dielectric measurement and optical observations, that suggests a relaxor–ferroelectric behavior. Below the transition temperature, the compound crystallizes in the monoclinic system, non-centrosymmetric space group Cc, with eight times the volume of the ambient phase: a=15.883(3), b=36.409(7), c=13.747(3) Å, β=120.2304(8)°, Z=16 and V=6868.7(2) ų. The organic moiety is then fully ordered within a supramolecular structure. Thermodiffractometry and thermogravimetric analyses indicate that its decomposition proceeds through three stages giving rise to the iron oxide.     

The Phase Relations in the System In2O3–TiO2–MgO at 1100 and 1350°C

The phase relations in the system In₂O₃–TiO₂–MgO at 1100 and 1350°C are determined by a classical quenching method. In this system, there are four pseudobinary compounds, In₂TiO₅, MgTi₂O₅ (pseudobrookite type), MgTiO₃ (ilmenite type), and Mg₂TiO₄ (spinel type) at 1100°C. At 1350°C, in addition to these compounds there exist a spinel-type solid solution Mg_2−xIn_2xTi_1−xO₄ (0≤x≤1) and a compound In₆Ti₆MgO₂₂ with lattice constants a=5.9236(7) Å, b=3.3862(4) Å, c=6.3609(7) Å, β=108.15(1)°, and q=0.369, which is isostructural with the monoclinic In₃Ti₂FeO₁₀ in the system In₂O₃–TiO₂–MgO. The relation between the lattice constants of the spinel phase and the composition nearly satisfies Vegard's law. In₆Ti₆MgO₂₂ extends a solid solution range to In₂₀Ti₁₇Mg₃O₆₇ with lattice constants of a=5.9230(5) Å, b=3.3823(3) Å, c=6.3698(6) Å, β=108.10(5)°, and q=0.360. The distributions of constituent cations in the solid solutions are discussed in terms of their ionic radius and site preference effect.     

New Layered Materials in the K–In–Ge–As System: K8In8Ge5As17and K5In5Ge5As14

Exploratory synthesis in the K–In–Ge–As system has yielded the unusual layered compounds K₈In₈Ge₅As₁₇(1) and K₅In₅Ge₅As₁₄(2), both of which contain In–Ge–As layers with interleaved potassium ions, Ge–Ge bonds, InAs₄tetrahedra, As–As bonds, and rows of Ge₂As₆dimers. Compound 1 has As₃groups, while compound 2 has infinite As ribbons on both faces of each layer. Unlike compound 1, compound 2 has substitutional defects where indium partially occupies each of the three independent germanium sites in the ratio of 1:5 for In:Ge. This partial occupancy makes 2 an electron-precise compound. The Ge(In)–Ge(In) bond of 2 is longer than the Ge–Ge bond of 1, and this bond lengthening effect was confirmed by performing DFT-MO calculations on the model compounds H₃Ge–GeH₃and H₃Ge–InH⁻₃. Possible implications of electron imprecise formulas determined by X-ray crystal structure determinations are discussed. Compound 1: space groupP2₁/cwitha=18.394 (8) Å,b=19.087 (7) Å,c=25.360 (3) Å,β=105.71 (2)°,V=8571 (4) ų, andD_calcd=4.45g/cm³forZ=4. Refinement on 4455 reflections yieldedR(R_w)=6.8%(7.8%). Compound 2: space groupC2/mwitha=40.00 (1) Å,b=3.925 (2) Å,c=10.299 (3),β=99.97 (2)°,V=1592 (1) ų, andD_calcd= 4.55g/cm³forZ=8. Refinement on 1206 reflections yieldedR(R_w)=5.6% (5.7%).     

Synthesis, crystal structure, and preliminary study of luminescent properties of InTbGe2O7

A new indium terbium germanate InTbGe₂O₇, which is a member of the thortveitite family, was prepared as a polycrystalline powder material by high-temperature solid-state reaction. This new compound crystallizes in the monoclinic system, space group C2/c (No. 15), with unit cell parameters a=6.8818(2) Å, b=8.8774(3) Å, c=9.7892(4) Å, β=101.401(1)°, V=586.25(4) ų and Z=4. Its structure was characterized by Rietveld refinement of powder laboratory X-ray diffraction data. It consists of octahedral sheets that are held together by sheets of isolated Ge₂O₇ diorthogroups composed of two tetrahedra sharing a common vertex. It contains only one octahedral site occupied by In³⁺ and Tb⁺³ cations. The characteristic mirror plane in the thortveitite (Sc₂Si₂O₇) space group (C2/m, No. 12) is not present in this new compound. Besides, in InTbGe₂O₇, the Ge–O–Ge angle bridging two diorthogroups is 156.8(2)° as compared to the one in thortveitite, which is 180°. On the other hand, luminescent properties were observed when it is excited with 376.5 nm wavelength. The luminescence spectrum shows typical transitions from the ⁵D₄ multiplet belonging to the trivalent terbium ion.     

Strontium–copper selenite–chlorides: Synthesis and structural investigation

Two new complex selenite–chlorides of strontium and copper Sr₂Cu(SeO₃)₂Cl₂ (I) and SrCu₂(SeO₃)₂Cl₂ (II) were obtained and characterized by X-ray diffraction technique, DTA and IR spectroscopy. Both compounds crystallize in the monoclinic system I: Sp. gr. P2₁/n, a=5.22996(3) Å, b=6.50528(4) Å, c=12.34518(7) Å, β=91.3643(2)°, Z=2; II: Sp. gr. P2₁, a=7.1630(14) Å, b=7.2070(14) Å, c=8.0430(16) Å, β=95.92(3)°, Z=2. Comparison of the crystal structure of (I) with the structures of Sr₂M(SeO₃)₂Cl₂ (M=Co, Ni) was performed. The substitution of strontium atom in the structure of (I) by Cu²⁺ ion with a 3d⁹ Jahn–Teller distorted surrounding leads to the lowering of the structure symmetry and to the appearance of the noncentrosymmetric structure of (II). The noncentrosymmetric character of the structure of (II) was confirmed by SHG signal (1.2 units relative to an α-quartz powder sample).     

Formation of helix-containing rods in a hybrid inorganic–organic material

The novel aluminum ethylenediphosphonate fluoride, [HN(CH₂CH₂NH₃)₃][Al₂(O₃PCH₂CH₂PO₃)₂F₂]·H₂O (1) (monoclinic, P2₁/n, a=12.145(4) Å, b=9.265(3) Å, c=20.422(6) Å, β=104.952(4)°, Z=3, R₁=0.092, wR₂=0.196) has been synthesized by solvothermal methods in the presence of tris(2-aminoethyl)amine and its structure determined using single microcrystal X-ray diffraction data. Compound 1 is a one-dimensional extended chain structure composed of well-separated anionic [Al₂(O₃PCH₂CH₂PO₃)₂F₂]⁴⁻ rods containing helical chains of corner-shared cis-AlO₄F₂ octahedra at their core. The charge-compensating tris(2-aminoethyl)ammonium cations separate the anionic [Al₂(O₃PCH₂CH₂PO₃)₂F₂]⁴⁻ rods that contain either left- or right-handed helical chains. The incorporation of the organic components into this hybrid material has aided the adoption of one-dimensionality by the compound and defined the pitch of the helical AlO₄F chain.