Hydrothermal synthesis of two supramolecular inorganic–organic hybrid phosphomolybdates based on Ni(ii) and Co(ii) ions: structural diversity and heterogeneous catalytic activities

Abstract

Two new hybrid compounds based on phosphomolybdates, namely (NHEPH 2 ) 5 [Ni II (P 4 Mo 6 O 31 ) 2 ]Á6H 2 O (1) and {(NHEPH 2 ) 2 [Co II (H 2 O) 6 ]}[P 2 Mo 5 O 23 ]Á2H 2 O (2) (NHEP = N-(2-hydroxyethyl)-piperazine), have been synthesized under hydrothermal conditions and characterized by elemental analyses, IR, TGA, single crystal X-ray diffraction and PXRD studies. In compound 1, Ni(II) is sandwiched between two {P 4 Mo 6 O 31 } 6À clusters and the residual negative charges are neutralized by NHEPH 2 2+ . In compound 2, the [P 2 Mo 5 O 23 ] 6À ion exists as a discrete moiety and the negative charges are compensated by both [Co(H 2 O) 6 ] 2+ and NHEPH 2 2+ . The extensive hydrogen bonding involving the organic cations and water molecules yielded three-dimensional (3D) open framework structures in these systems. These phosphomolybdate based compounds showed good catalytic efficiency in heterogeneous oxidation of styrene in the presence of an environmentally benign oxidant, H 2 O 2 , under mild conditions.Again, the construction of a simple metal-organic framework system can also be achieved by using simple transition metal cations and/or organic amine cations to balance the charge on the POM units. In this paper, we report two inorganic-organic hybrid materials formed from phosphomolybdates, namely

Dyes Adsorption Behavior of Fe3O4 Nanoparticles Functionalized Polyoxometalate Hybrid

“…Phosphomolybdates are key to this issue due to their special structure and potential application in water pollution treatment [14,15,16]. One of the most prominent structures of phosphomolybdate is [P 2 Mo 5 O 23 ] 6− .…”

Three-Dimensional Interpenetrating Frameworks Based on {P4Mo6} Tetrameric Clusters and Filled with In Situ Generated Alkyl Viologens

“…As a significant member of the polyoxomolybdate library, [P 4 Mo 6 O 31 ] 12– (denoted as {P 4 Mo 6 }) demonstrates the following advantages: (i) it possesses many coordination sites where the Mo–O bonds can interact with the metal cation to form stable dimers and the P–O bonds can provide versatile coordination sites to various linking units; (ii) the {P 4 Mo 6 } units can facilitate multidirectional coordination connections to connect one or both metal ions, thus forming novel compounds with numerous topological structures and excellent properties. Various research works were devoted to the assembly of poly­(oxomolybdophosphate) anions into one-dimensional (1-D) polymers, − two-dimensional (2-D) structures, − and three-dimensional (3-D) microporous frameworks. − Hitherto, the trimeric/tetrameric species and high-dimensional structures were obtained using the Keggin/Dawson fragments, − while only a few examples based on {P 4 Mo 6 } are available. − As reported, the {P 4 Mo 6 } tetrameric clusters combined with transition metal complexes generally use H 3 PO 4 /Na 3 PO 4 and Na 2 MoO 4 /MoO 3 as their phosphorus and molybdenum sources and molybdenum powder, phosphite, and organic N-containing ligands as their reductants …”

Preparation of Fe3O4@polyoxometalates Nanocomposites and Their Efficient Adsorption of Cationic Dyes from Aqueous Solution

“…Polyoxometalate hybrid systems provide a new pathway for combining multiple functional groups in a nano structure, which demonstrates great potential for application in selective adsorption [12]. Phosphomolybdates are a unique class of polyoxometalates, which have attracted increasing attention owing to its unique structure and potential application in the removal of dyes [13,14]. In particular, Strandberg-type phosphomolybdate [P 2 Mo 5 O 23 ] 6− has been extensively studied.…”