Syntheses, crystal structures, thermal stabilities, luminescence and magnetism of two 3D pillared metal phosphonates

Abstract

Two pillared metal phosphonates: [Mn₃(4,4′-bipy)(L)₂]·(4,4′-bipy)_0.5 (1) and [Co₃(4,4′-bipy)(H₂O)₂(L)₂]·(4,4′-bipy)_0.5 (2) (L = O₃PCH(OH)CO₂), have been synthesized hydrothermally, and characterized by single-crystal X-ray diffraction along with powder XRD, EA, IR and TGA. In compounds 1–2, Mn(II) and Co(II) ions are in octahedron coordination geometries and bridged by 2-hydroxyl(phosphono)acetate through -OH, -COO and -PO₃ groups into a hybrid layer. The layers are further pillared by the coordinated 4,4′-bipy into a 3D neutral framework possessing 1D parallelogram-shaped channels with approximate sizes 9 × 11 Ų, which are occupied by the isolated 4,4′-bipy. Solid 1 is thermally stable up to 300 °C under an air atmosphere and displays a purple-blue luminescence. The results of magnetic measurement indicate solid 1 is a metamagnet.