Ln 2(O 2CCH 2PO 3) 2(H 2O) 3 · H 2O (Ln = La, Pr, Nd, Sm): Layered lanthanide phosphonoacetates containing two-dimensional –Ln–O– linkages

Abstract

Four novel isostructural lanthanide phosphonate compounds with formula Ln 2(O 2CCH 2PO 3) 2(H 2O) 3 · H 2O [Ln = La ( 1), Pr ( 2), Nd ( 3), Sm ( 4)] have been prepared through hydrothermal reactions of phosphonoacetate acid and lanthanide nitrates. All show layered structures made up of {LnO 9} polyhedra and {CPO 3} tetrahedra with the lattice water molecules locating between the layers. Within the layer, chains of edge-sharing {LnO 9} polyhedra are connected via corner-sharing by phosphonate oxygens forming a two-dimensional –Ln–O– linkage. Thermal analyses and XRD measurements reveal that the framework structures can be maintained up to 400 °C.