Articles written in Journal of Chemical Sciences

    • Synthesis and characterization of a reduced heteropoly-tungstovanadate: (NH4)7[VvO4W10IVV2IVO36].ca. 22H2O

      Vaddypally Shivaiah Samar K Das

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      The compound (NH4)7[ VvO4W10VIV2VIO36]·ca.22H2O (1) has been synthesized from an aqueous ammonium acetate buffer (pH 4) containing sodium vanadate, sodium rungstate_and sodium dithionite. Compound (1) crystallizes in a cubic space groupFm — 3, witha = 22.2001(6) Å and Z = 8. The anion [VvO4W10VIV2IVO36]7- is a typical Keggin type structure with VVO4 as the central tetrahedron. (1) has further been characterized by elemental analyses, redox titration, IR, EPR, and electronic spectroscopy and room temperature magnetic moment measurement.

    • Supramolecular assembly based on a heteropolyanion: Synthesis and crystal structure of Na3(H2O)6[Al(OH)6Mo6O18]·2H2O

      Vaddypally Shivaiah Samar K Das

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      Synthesis and structural characterization of a polyoxometalate compound Na3(H2O)6 [Al(OH)6Mo6O18]-2H2O (1) have been described. Compound1 exhibits three-dimensional network structure in the solid state, which is assembled by Anderson-type heteropolyanions, [Al(OH)6Mo6O18]n3n-, as building blocks sharing sodium cations.1 possesses “sinuous” channels occupied by supramolecular water dimers as guests. Anderson anions, sodium-coordinated water and crystal water are additionally involved in an intricate hydrogen-bonding network in the crystal of1.

    • Polyoxometalates: Toward new materials

      A Srinivasa Rao T Arumuganathan Vaddypally Shivaiah Samar K Das

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      This article describes an account of some of our polyoxometalate (POM)-based research, we have been doing in our laboratory last several years. There are several well-defined POM cluster anions, that are structurally characterized. We have chosen Anderson-type of heteropolyanion [Al(OH)6Mo6O18]$^{3−}$ and explored its linking propensity in different dimensions using `s', `d' and `f' block elements as linkers.We have demonstrated how a lanthanide linker provides a new pathway in forming a two-dimensional linked {As8V14} system [{Ln(H2O)6}2As8V14O42(SO3)]$_n$.8nH2O, that is derived from discrete {As8V14} cluster containing compound (NH4)6[As8V14O42(SO3)]. A polyoxometalate compound has been described in which a reduced tungstovanadate-heteropolyanion clusters get linked via capped V = O groups into one-dimensional chains. All these systems have already been reported elsewhere. The last portion of this article will be described by a new system [3-ampH]6[V10O28]$\cdot$2H2O having discrete molecular structure and extended supramolecular structure.

    • Coordination of lanthanide cation to an Anderson type polyoxometalate anion leads to isomorphous metal-oxide based one-dimensional inorganic solids: Synthesis, crystal structure and spectroscopy

      Vaddypally Shivaiah Tanmay Chatterjee Samar K Das

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      One-dimensional isomorphous inorganic polymers containing Anderson type heteropoly anion as a basic building unit, namely [La(H2O)7Cr(OH)6Mo6O18]$_n$·4nH2O (1), [Gd(H2O)7Cr(OH)6Mo6O18]$_n$·4nH2O (2), [Gd(H2O)7Al(OH)6Mo6O18]$_n$·4nH2O (3), and [Eu(H2O)7Al(OH)6Mo6O18]$_n$·4nH2O (4) have been synthesized and studied by the powdered X-ray diffraction, TGA, IR, electronic and ESR spectroscopy, and unambiguously by single crystal X-ray crystallography. Isomorphous compounds 1-4 are crystallized in orthorhombic system with $Pca2_1$ space group. The crystal structure analysis reveals a one-dimensional extended chain in which the Anderson type heteropolyanion, acting as the building unit, is linked by rare earth metal ions in a zig-zag fashion. In the crystal structure, all types of oxygens of the heteropolyanion, lattice waters, lanthanum coordinated waters are extensively involved in O—H…O hydrogen bonding interactions. Compounds are additionally characterized by UV-visible and ESR spectroscopy.

    • A gas–liquid interface synthesis in polyoxometalate chemistry: potential bag filter for volatile organic amines


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      Diffusion of piperidine and pyridine into an acidified aqueous solution of Na2MoO4, yield compounds [(pipH)4][Mo8O26] · 4H2O (pip = piperidine = C5H11N) (1) and [(pyH)4][Mo8O26] (py =pyridine = C5H5N) (2), respectively. Compound 1 possesses supramolecular 3-D network and the relevant connectivity pattern generates channels of approximate dimensions of 10.76 × 11.57´A° 2, in which the piperidinium cations are located as guests. Multidimensional supramolecular frameworks (3-D in compound 1 and 2-D layer type of network in compound 2) have been made possible, as the organic cations and polyoxometalate (POM) anions are glued together by significant hydrogen bonding interactions. The synthesis of compounds 1 and 2 provides a unique ‘gas–liquid’ synthetic route in POM chemistry that result in organic–inorganic hybrid materials with structural diversities. This synthetic approach, first time in POM chemistry, can be described as a potential bag filter for volatile organic amines.

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