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

Hydrothermal reactions of Zn(II) or Pb(II) ions with 4-pyridyl-CH2N(CH2COOH)(CH2PO3H2) (H3L) afforded two metal phosphonates, namely, [Zn-3(L)(2)]center dot 2H(2)O (1) and [Pb-3(L)(2)(H2O)(2)]center dot H2O (2). Compound 1 is a 3D pillared framework in which [ZnO4] tetrahedra and [ZnO3N2] trigonal-bipyramids are connected by L3- anions with heptadentate modes. In 2, L3- anions exhibit pentadentate modes to combine Pb(II) ions into a complicated 2D hybrid layer, resulting in the non-coordinated pyridine rings being sandwiched between the layers. Solid 1 is thermally stable up to 350 degrees C under an air atmosphere and displays bright purple-blue luminescence, and the luminescent intensity of the hydrated solid 1 can be weakened by nitrobenzene.