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

Hydrothermal reactions of ZnII or CuII ion with 1-hydroxyl-2-(3-pyridyl)ethylidene-1,1-diphosphonic acid (H4L) afforded two metal phosphonates, namely, [Zn2(L)(H2O)] (1) and [Cu4(L)2 (H2O)4]·(H2O)1.25 (2). In 1, [ZnO3N], [ZnO4] and [PO3C] tetrahedra are connected through corner-sharings to form a 3D framework with a 14MR ellipsoid-like channel. In 2, the [PO3C] tetrahedron also shares corners with a copper square-pyramid ([CuO4N], [CuO5]) into a hybrid layer, which is further pillared by L4− anion into a 3D neutral framework. Solid 1 is thermally stable up to 250 °C under an air atmosphere and displays UV luminescence. More interestingly, the dehydrated phase of 1 is selective and reversible for sensing of nitrobenzene. And the magnetic property of 2 has also been studied.