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Hydrothermal Methods (hydrothermal + methods)
Selected AbstractsHierarchical Structures in Tin(II) OxalatesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2008Padmini Ramaswamy Abstract Six new SnII oxalates exhibiting a hierarchy of structures have been prepared employing hydrothermal methods. The compounds I [C10N2H10][Sn(C2O4)2], II [C10N2H10][Sn2(C2O4)3], and III [C8N4H26][Sn(C2O4)2]2·2H2O possess zero-dimensional molecular structures; IV [C10N2H8]2[Sn(C2O4)]2 and V [C12N2H8][SnC2O4] have one-dimensional chain structures; and compound VI [C5N2H14]2[Sn4(C2O4)6]·7H2O has a two-dimensional layer structure. The SnII ions have 4- and 6-coordination with square-pyramidal or pentagonal-bipyramidal geometry, in which the lone pair of electrons also occupies one of the vertices. Weak intermolecular forces such as hydrogen-bond interactions, ,···, interactions, and lone-pair,, interactions have been observed and appear to lendstructural stability. Theoretical studies indicate that the ,···, interaction energy between the bound 1,10-phenanthroline molecules is of the order of 5,6 kcal,mol,1 in V. Natural bond orbital (NBO) analysis on two model compounds, II and IV, indicates reasonable lone-pair,, interactions. The close structural relationship between all the compounds indicates that a building-up process from the zero-dimensional monomer can be considered. The present structures provide opportunities for evaluating the structure-directing role of the lone pair of electrons of SnII.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Amine-Intercalated Layered SnII Phosphates with Open-Framework StructuresEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 17 2006Padmini Ramaswamy Abstract Three new SnII phosphate materials, [NH3(CH2)3NH2(CH2)2NH2(CH2)3NH3]·2[Sn2P2O8] (I), [(N2C5H14)2][Sn4P4O16]·3H2O (II) and [(N2C5H14)][Sn2P2O8]·H2O (III), have been synthesised by means of hydrothermal methods using N,N, -bis(3-aminopropyl)ethylenediamine (BAPEN; for I) and homopiperazine (H-PIP; for II and III), respectively, as the structure-directing organic amines. The solids I,III have layered architectures. The structures of all three compounds consist of strictly alternating vertex-sharing trigonal-pyramidal SnO3 and tetrahedral PO4 moieties forming infinite layers possessing apertures bound by 4- and 8-T atoms (T = Sn, P). The distorted 4- and 8-membered apertures within the layers suggest the subtle influence of the lone-pair of electrons of SnII on the structure. The interlamellar space is occupied by the protonated organic amine molecules which interact with the framework through N,H···O hydrogen bonding. The compounds I,III bear some structural relationship to the layered zinc phosphite phases. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Hydrothermal Synthesis, Structure and Magnetic Properties of a One-Dimensional Iron Arsenate, 1,[NH3(CH2)2NH(CH2)2NH3][Fe2F4(HAsO4)2]EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 19 2004Sandip Chakrabarti Abstract A novel one-dimensional iron arsenate, 1,[NH3(CH2)2NH(CH2)2NH3][Fe2F4(HAsO4)2], built up exclusively from SBU-4 units (two octahedral units sharing an edge and connected through two tetrahedra) with Fe3+ ions in the high-spin state has been synthesized by hydrothermal methods. Structure elucidation reveals that the compound is a two-leg ladder with very weak antiferromagnetic exchanges along the chains. The magnetic susceptibility data show activated behaviour at T = 14 K, suggesting a finite spin gap between the nonmagnetic ground state and the excited triplet state. We have estimated the exchange parameters theoretically based on the S = 5/2 Majumdar,Ghosh model with frustrations and dimerisations. Although the magnetic gap is quite small, this is the first example, to the best of our knowledge, where the rungs with two S = 5/2 spins form strong singlet dimers. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] catena -Poly[bis{,-dihydrogen [(5-carboxypentylimino)dimethylene]diphosphonato-,2O:O,}cadmium(II)]ACTA CRYSTALLOGRAPHICA SECTION C, Issue 9 2009Shao-Ming Ying The title compound, [Cd(C8H18NO8P2)2]n, synthesized by hydrothermal methods, exhibits a layered structure in which the CdII ion, occupying a centre of symmetry, is coordinated by six O atoms from four phosphonate ligands. The crosslinkage of CdO6 octahedra by bridging phosphonate ligands results in a cadmium(II) phosphonate layer. Within the layer, there exists a 16-membered ring incorporating four ,Cd,O,P,O, linkages. The uncoordinated carboxyl group of the ligand is oriented so that it penetrates the adjacent layer, taking part in hydrogen bonding to two uncoordinated phosphonate O atoms to form a CO2H/HO2P motif. [source] Metal,Organic Perovskites: Synthesis, Structures, and Magnetic Properties of [C(NH2)3][MII(HCOO)3] (M=Mn, Fe, Co, Ni, Cu, and Zn; C(NH2)3= Guanidinium)CHEMISTRY - A EUROPEAN JOURNAL, Issue 44 2009Ke-Li Hu Abstract We report the synthesis, crystal structures, and spectral, thermal, and magnetic properties of a family of metal,organic perovskite ABX3, [C(NH2)3][MII(HCOO)3], in which A=C(NH2)3 is guanidinium, B=M is a divalent metal ion (Mn, Fe, Co, Ni, Cu, or Zn), and X is the formate HCOO,. The compounds could be synthesized by either diffusion or hydrothermal methods from water or water-rich solutions depending on the metal. The five members (Mn, Fe, Co, Ni, and Zn) are isostructural and crystallize in the orthorhombic space group Pnna, while the Cu member in Pna21. In the perovskite structures, the octahedrally coordinated metal ions are connected by the anti,anti formate bridges, thus forming the anionic NaCl-type [M(HCOO)3], frameworks, with the guanidinium in the nearly cubic cavities of the frameworks. The Jahn,Teller effect of Cu2+ results in a distorted anionic Cu,formate framework that can be regarded as Cu,formate chains through short basal CuO bonds linked by the long axial CuO bonds. These materials show higher thermal stability than other metal,organic perovskite series of [AmineH][M(HCOO)3] templated by the organic monoammonium cations (AmineH+) as a result of the stronger hydrogen bonding between guanidinium and the formate of the framework. A magnetic study revealed that the five magnetic members (except Zn) display spin-canted antiferromagnetism, with a Néel temperature of 8.8 (Mn), 10.0 (Fe), 14.2 (Co), 34.2 (Ni), and 4.6,K (Cu). In addition to the general spin-canted antiferromagnetism, the Fe compound shows two isothermal transformations (a spin-flop and a spin-flip to the paramagnetic phase) within 50,kOe. The Co member possesses quite a large canting angle. The Cu member is a magnetic system with low dimensional character and shows slow magnetic relaxation that probably results from the domain dynamics. [source] Spontaneous Resolution of Chiral Polyoxometalate-Based Compounds Consisting of 3D Chiral Inorganic Skeletons Assembled from Different Helical UnitsCHEMISTRY - A EUROPEAN JOURNAL, Issue 32 2008Ya-Qian Lan Dr. Abstract Four enantiomerically pure 3D chiral POM-based compounds, [Ni2(bbi)2(H2O)4V4O12],2,H2O (1,a and 1,b) and [Co(bbi)(H2O)V2O6] (2,a and 2,b) (bbi=1,1,-(1,4-butanediyl)bisimidazole) based on the achiral ligand, different vanadate chains, and different metal centers have been synthesized by hydrothermal methods. Single-crystal X-ray diffraction analyses revealed that 1,a and 1,b, and 2,a and 2,b, respectively, are enantiomers. In 1,a and 1,b two kinds of vanadate chains with different screw axes link Ni cations to generate 3D chiral inorganic skeletons, which are connected by the achiral bbi ligands to form complicated 3D 3,4-connected chiral self-penetrating frameworks with (72,8)(72,82,92)(73,82,10) topology. They represent the first examples of chiral self-penetrating frameworks known for polyoxometalate (POM) systems. Contrary to 1,a and 1,b, in 2,a and 2,b the vanadate chains link CoII cations to generate 3D chiral inorganic skeletons, which are assembled from two kinds of heterometallic helical units of opposite chirality along the c axes. The chiral inorganic skeletons are connected by bbi to form 3D 3,4-connected chiral POM-based frameworks with (62,8)2(62,82,102) topology. It is believed that the asymmetrical coordination modes of the metal cations in 1,a,2,b generate the initial chiral centers, and that the formation of the various helical units and the hydrogen bond interactions are responsible for preservation of the chirality and spontaneous resolution when the chirality is extended into the homochiral 3D-networks. This is the first known report of chiral POM-based compounds consisting of 3D chiral inorganic skeletons being obtained by spontaneous resolution upon crystallization in the absence of any chiral source, which may provide a rational strategy for synthesis of chiral POM-based compounds by using achiral ligands and POM helical units. [source] Inorganic,Organic Hybrid Structures: Open-Framework Iron Phosphite,Oxalates of Varying DimensionalityCHEMISTRY - A EUROPEAN JOURNAL, Issue 3 2007Sukhendu Mandal Abstract Inorganic,organic hybrid structures belonging to the family of iron phosphite,oxalates have been prepared by employing hydrothermal methods. Their structures, determined by single-crystal X-ray diffraction, show a hierarchy within the family. While compounds I and II are low dimensional, III,VI have three-dimensional structures. Compound I has edge-shared ladders of iron phosphite with oxalate units hanging from the iron centers. Compound II has a layer structure with a honeycomb-like arrangement. The three-dimensional hybrid structures have the oxalate units connected in both in-plane and out-of-plane modes. A newly identified secondary building unit (SBU-7) and the oxalate units satisfying the valence and coordination requirements in the structure of V are novel and noteworthy structural features. Magnetic studies show that the dominant interactions between the iron centers are antiferromagnetic. Similar to other known hybrid structures, the phosphite,oxalate structures appear to show wide compositional and structural diversity. [source] Solar Cells by Design: Photoelectrochemistry of TiO2 Nanorod Arrays Decorated with CdSeADVANCED FUNCTIONAL MATERIALS, Issue 12 2010Jin Ho Bang Abstract One-dimensional (1D) nanostructures of TiO2 are grown directly on transparent, conductive glass substrate using hydrothermal/solvothermal methods. When employed as a photoanode in photoelectrochemical cells, the vertically aligned TiO2 nanorod array exhibits slower charge recombination at electrolyte interface as compared to mesoscopic TiO2 particulate film. Electrochemical deposition of CdSe onto TiO2 nanorod array is carried out to extend absorption into visible light region. The role of CdSe-sensitized, 1D rutile TiO2 architecture in the solar cell design is discussed. [source] | ||||||||||