Organically-functionalised supertetrahedra as building blocks for hybrid materials
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1148-PP10-07
Organically-functionalised supertetrahedra as building blocks for hybrid materials Paz Vaqueiro and M. Lucia Romero Department of Chemistry, Heriot-Watt University, Edinburgh EH14 4AS, UK ABSTRACT The crystal structures of gallium sulfides prepared under solvothermal conditions, using 4-picoline as a solvent, are described. These materials contain [Ga10S16(NC6H7)4]2- clusters, in which the terminal S2- anions have been replaced by covalently bonded 4-picoline molecules. Whilst these phases contain isolated supertetrahedral clusters separated by organic moieties, linkage of such clusters via organic ligands is possible under suitable reaction conditions. These organically-functionalised supertetrahedra could therefore be used to design novel MetalOrganic frameworks (MOFs) in which the normally-encountered metal centers are replaced by supertetrahedral clusters. INTRODUCTION Metal-sulfide supertetrahedral clusters, which can be described as tetrahedrally shaped fragments of the cubic ZnS-type lattice, have been increasingly used as building blocks for the solvothermal synthesis of wholly inorganic three-dimensional frameworks.[1] Examples include [(CH3)4N]2MGe4S10 (M=Mn, Fe, Cd), which exhibits a non-interpenetrating diamond lattice in which the tetrahedral diamond sites are replaced with alternating [Ge4S10]4- clusters and MS46tetrahedra.[2] Larger supertetrahedral [In10S20]10- clusters linked into non-interpenetrating indium-sulfide frameworks,[3] as well as three-dimensional materials containing heterometallic clusters, such as [M4In16S33]10- (M=Mn, Co, Zn, Cd), have also been described.[4] Threedimensional supertetrahedral frameworks consisting of two-interpenetrating diamond lattices, have been found in a number of gallium sulfides.[5,6] Although other structural types can be prepared, interpenetrating and non-interpenetrating diamond lattices are the most commonly found topology. The relatively small number of structural types observed could be attributed to the lack of flexibility of the metal-sulfur-metal angle. In order to obtain new three-dimensional frameworks, it is necessary to devise alternative ways of linking the clusters. In the preparation of the materials described above, organic amines or alkylammonium cations are generally be employed as templates, to exert a structure directing effect on the crystallization process. These template molecules are generally incorporated into the structure through weak hydrogen bonding. By contrast, we have found that in the gallium-sulfur system, covalent bonding between the metal and the amine molecules is possible.[7] We have exploited the ability of gallium to form covalent bonds with amines under solvothermal conditions, to prepare organically-functionalised supertetrahedra, in which the gallium atoms at the corners of the cluster exhibit a tetrahedral environment through additional coordination to organic ligands.[8] Our current synthetic efforts are directed at exploiting such organically-functionalised supertetrahedra as building blocks for inor
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