• Minakshi Asnani

      Articles written in Journal of Chemical Sciences

    • Hydrothermal synthesis of a new ethylenediammonium intercalated vanadyl phosphate, (H3NCH2CH2NH3)0.5[V0.324+V0.685+O2PO4{P(OH)2}0.44]0.44]

      P Ayyappan Minakshi Asnani A Ramanan Y Piffard

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      In this paper we report the hydrothermal synthesis and characterisation of a new ethylenediammonium intercalated vanadyl phosphate, (H3NCH2CH2NH3)0.5 [V0.324+V0.685+O2PO4P(OH)20.44]. The phase purity of the solid was established using powder X-ray diffraction, single crystal X-ray diffraction, TGA, DTA, FTIR, UV-Vis and magnetic susceptibility measurements. Crystal data: orthorhombic,Pnma,a = 90289,b = 8.8962 andc = 15.9813 Å,V = 1283.7Å3,Z = 8. The structure contains layers made of VO5 square pyramids and PO4 tetrahedra; adjacent layers are connected through disordered tetrahedral PO2(OH)2 units. Ethylenediammonium cations occupy cavities in between the layers.

    • Crystallization of organically templated phosphomolybdate cluster-based solids from aqueous solution

      Minakshi Asnani Dinesh Kumar T Duraisamy Arunachalam Ramanan

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      The paper reports the synthesis and structural characterization of several organic-inorganic solids involving phosphomolybdate clusters. The Strandberg-type {P2Mo$^{\text{VI}}_5$O23} and the lower-valent {P4Mo$^V_6$O31} cluster based solids were isolated in the presence of $en$ (ethylenediamine) by controlling pH of the reaction medium. The lower-valent cluster invariably requires the presence of a suitable metal cation for further stabilization. A detailed investigation of the system was carried out where three different weak acids viz. oxalic acid, succinic acid and glycine were used in the entire pH range (1-12). Our results establish that the organic amine ($en$) is alone capable of reducing the molybdenum core in the absence of an organic acid at a suitable pH. Hence, pH of the reaction medium combined with suitable temperature favours the formation of lower-valent phosphomolybdate cluster. Higher pH favours the precipitation of a new sodium hydrogen phosphate.

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