Ca7.96Cu0.04Ge5O18: a new calcium germanate with GeO4 and Ge3O10 units

The title compound, octa­calcium copper penta­germanium octa­deca­oxide, represents a new inter­mediate phase between CaO and GeO₂, and has not previously been reported in the literature. The structure consists of three different Ge sites, two of them on general 8d positions, site symmetry 1, one on special position 4d, site symmetry 2. Three of the five Ca sites occur on 8d positions, site symmtery 1, one Ca is on 4b with site symmetry and one Ca is on 4c with site symmetry 2. All nine O atoms have symmetry 1 (8d position). By sharing common edges, the Ca sites form infinite bands parallel to the c axis, and these bands are inter­connected by isolated GeO₄ and Ge₃O₁₀ units. These (100) layers are stacked along a in an ABAB… sequence, with the B layer being inverted and displaced along b/2.     

K3(U3O6)(Si2O7) and Rb3(U3O6)(Ge2O7): a pentavalent-uranium silicate and germanate

A new uranium(V) silicate, K3(U3O6)(Si2O7), and the germanate analogue, Rb3(U3O6)(Ge2O7), have been synthesized under high-temperature, high-pressure hydrothermal conditions and characterized by single-crystal X-ray diffraction. Their structures contain uranate columns formed of triple octahedral chains of the alpha-UF5 type linked by disilicate (or digermanate) units to form a 3-D framework structure. The valence state of uranium is confirmed by X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, and magnetic susceptibility.     

Upconversion luminescence and ratiometric temperature sensing behavior of Er3+/Yb3+-codoped CaY2Ge3O10 germanate

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High-pressure synthesis and superconductivity of a new binary lanthanum germanide LaGe3 with triangular Ge3 cluster units

We prepared a new binary lanthanum germanide, LaGe(3), under high-pressure and high-temperature conditions (3-12 GPa, 500-1200 °C). It crystallizes in the BaPb(3) structure (the space group R ?3m) with lattice constants of a = 6.376(1) ?, c = 22.272(3) ?, and V = 784.1(2) ?(3). We refined the structure using Rietveld analysis from X-ray powder data. The structure is composed of two types of close-packed atom layers. In one layer, every La atom is surrounded solely by Ge atoms with the same distance of 3.188 ?. The other layer contains Ge(3) regular, triangular cluster units with a Ge-Ge distance of 2.634 ?. The electron localization function and crystal orbital Hamilton population calculations suggest that the triangular cluster is composed of three Ge-Ge covalent bonds and that each Ge atom has a lone pair. The temperature dependence of the magnetic susceptibility and electrical conductivity measurements revealed that LaGe(3) is metallic and shows superconductivity at 7.4 K. This critical temperature is highest for the La-Ge system.     

Cs3UGe7O18: a pentavalent uranium germanate containing four- and six-coordinate germanium

A pentavalent uranium germanate, Cs(3)UGe(7)O(18), was synthesized under high-temperature, high-pressure hydrothermal conditions at 585 °C and 160 MPa and structurally characterized by single-crystal X-ray diffraction and infrared spectroscopy. The valence state of uranium was confirmed by X-ray photoelectron spectroscopy and electron paramagnetic resonance. The room-temperature EPR spectrum can be simulated with two components using an axial model that are consistent with two distinct sites of uranium(V). In the structure of the title compound, each ([6])GeO(6) octahedron is bonded to six three-membered single-ring ([4])Ge(3)O(9)(6-) units to form germanate triple layers in the ab plane. Each layer contains nine-ring windows; however, these windows are blocked by adjacent layers. The triple layers are further connected by UO(6) octahedra to form a three-dimensional framework with intersecting six-ring channels along the <1 ?10> directions. The Cs(+) cation sites are fully occupied, ordered, and located in the cavities of the framework. Pentavalent uranium germanates or silicates are very rare, and only two uranium silicates and one germanate analogue have been published. However, all of them are iso-structural with those of the Nb or Ta analogues. In contrast, the title compound adopts a new structural type and contains both four- and six-coordinate germanium. Crystal data of Cs(3)UGe(7)O(18): trigonal, P3?c1 (No. 165), a = 12.5582(4) ?, c = 19.7870(6) ?, V = 2702.50(15) ?(3), Z = 6, D(calc) = 5.283 g·cm(-3), μ(Mo Kα) = 26.528 mm(-1), R(1) = 0.0204, wR(2) = 0.0519 for 1958 reflections with I > 2σ(I). GooF = 1.040, ρ(max,min) = 1.018, and -1.823 e·?(-3).     

Zinc complexes of T-shaped trans-1,2,3-propenetricarboxylic acid with 1-D ribbon-like chain, 2-D rhombus-grid-like and herringbone-like layers, and non-interpenetrating 3-D open framework

Five zinc complexes of T-shaped trans-1,2,3-propenetricarboxylic acid (H(3)L) with 1-D ribbon-like chain, 2-D rhombus-grid-like and herringbone-like layers, and non-interpenetrating 3-D open framework have been obtained based on different building blocks. X-ray single crystal analyses show that the T-shaped information of H(3)L was nicely expressed in the construction of herringbone-like or ladder-like structure. All compounds were found to display blue fluorescent emissions.     

Synthesis and characterization of two 3-D polymeric lanthanide complexes constructed from 1,2,4,5-benzenetetracarboxylic acid

Two new 3-D lanthanide coordination polymers, [CeK(btec)(H₂O)₂] _n (1), [Ho(btec)_0.5(ad)_0.5(H₂O)] _n (2) (H₄btec?=?1,2,4,5-benzenetetracarboxylic acid, H₂ad?=?adipic acid), have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. Structural analyses reveal that both complexes crystallized in monoclinic space group P2₁/c and possessed 3-D net-structures. In 1, btec adopts two types of coordination modes: µ₁₂–η²:η²:η²:η¹:η²:η²:η²:η¹ bridging mode linking six Ce(III) ions and six K⁺ ions and the other µ₈–η¹:η²:η²:η¹:η¹:η²:η²:η¹ bridging mode connecting four Ce(III) ions and four K⁺ ions. In 2, btec adopts a µ₆-bridging with each carboxylate group of btec ligand in a µ₂–η¹–η² mode, the adipate is µ₄-bridging with each carboxylate µ₂–η¹–η¹-monodentate. The topological analysis shows that 1 can be simplified to a 3-nodal net with the Schläfli symbol {3²,4⁸,5³,6²}₄{3⁴,4¹²,5¹²}{4³⁸,6²⁶,8²} and 2 can be simplified to a 3-nodal network with the Schläfli symbol {4²,8⁴}{4⁶,6⁶,8³}{4⁷,6³}₂. The thermogravimetric analyses and the X-ray powder diffraction of 1 and 2 are discussed.     

Synthesis and characterization of two 3-D polymeric lanthanide complexes constructed from 1,2,4,5-benzenetetracarboxylic acid

Two 3-D porous coordination polymers, [Nd(^abtec)_2/4(^bbtec)_2/4(H₂O)] _n (1) and [NdYb(^cbtec)_2/4(^dbtec)_2/4(^ebtec)_2/4(H₂O)₄] _n (2), have been prepared by the hydrothermal method at 160°C. Both complexes were characterized by elemental analyses, photoluminescence spectra, and single-crystal X-ray diffraction.     

A 3-D cobalt(II)-coordination polymer with mixed-connected network topology constructed from 4-pyridin-3-yl-benzoic acid

A new coordination polymer, [Co₂(μ-H₂O)(4,3-pybz)₄] _n (1), has been hydrothermally synthesized from Co(NO₃)₂ · 6H₂O and an unsymmetrical 4-pyridin-3-yl-benzoic acid (4,3-Hpybz), which is characterized by IR, elemental analysis, thermogravimetric analysis, and single crystal X-ray diffraction. This compound crystallizes in monoclinic, space group C2/c with a = 11.876(3) Å, b = 15.462(3) Å, c = 21.545(4) Å, β = 94.873(5)°, V = 3942.0(15) ų, Z = 4, Dc = 1.565 g cm^?3, F(000) = 1904, GOF = 1.025, μ = 0.910 mm^?1, R ₁ = 0.0456, wR ₂ = 0.0983. Compound 1 shows a 3-D (3,6)-connected coordination framework with (3.4.5)(3².4⁴.5⁵.6².7²) topology, in which cobalt is a six-connected node, and the 4,3-Hpybz ligands serve as two-connected spacers and three-connected nodes. In addition, the magnetic and thermal properties of 1 have also been investigated.     

Two 3-D metal-organic frameworks constructed by 2-methyl or 2-ethyl imidazole dicarboxylates

Two polymeric frameworks, [Zn₅(MIDC)₂(HMIDC)₂(phen)₅] _n (1) (H₃MIDC?=?2-methyl-1H-imidazole-4,5-dicarboxylic acid, phen?=?1,10-phenanthroline) and {[Ca₂(HEIDC)₂(H₂O)]?·?H₂O} _n (2) (H₃EIDC?=?2-ethyl-1H-imidazole-4,5-dicarboxylic acid), have been solvothermally synthesized and structurally characterized by single-crystal X-ray diffraction. Compound 1 exhibits a 3-D structure constructed from 2-D layer motifs joined by µ ₂-HMIDC^2? or µ ₃-MIDC^3? ligands. Compound 2 also presents a 3-D framework, generated from 1-D chains linked by HEIDC^2? ligands by two different µ₅-modes. The thermal and solid-state photoluminescence properties of both the complexes have been determined.     

Use of a summation technique for evaluation of the phase transition in lead germanate,Pb5Ge3O11

A computer technique is outlined to increase the signal: noise ratio of DSC results for transformations involving small changes of energy. The method is applied to determine the transformation temperature of the ferroelectric-paraelectric transformation of lead germanate, Pb₅Ge₃O₁₁, either pure or doped with Nd³⁺ or with Nd³⁺+K⁺.

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Zusammenfassung Eine Computermethode wird angegeben, die es erlaubt, das Signal: Rausch-Verhältnis bei DSC-Messungen von Umwandlungen mit geringer Energie zu erhöhen. Diese Methode wird verwendet, um die Temperatur der Umwandlung ferroelektrisch-paraelektrisch an Bleigermanat Pb₅Ge₃O₁₁, rein oder dotiert mit Nd³⁺ oder mit Nd³⁺ +K⁺, zu bestimmen.

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Thanks are due to Dr. H. D. Kürsten, who prepared the crystals.