ZINC, CADMIUM AND LEAD DIPHOSPHONATES: SYNTHESES, STRUCTURES AND LUMINESCENT PROPERTIES AND THEIR POTENTIAL AS SOFT-OXOMETALATE PRECURSORS

Abstract

Four new metal diphosphonates Zn ( pyHhedpH )⋅ H 2 O (1), Cd ( pyHhedpH )⋅ H 2 O (2), Pb ( pyHhedpH )⋅ H 2 O (3) and Pb 2( pyHedpH )2(4) (pyHhedpH3 = 2-(4-pyridyl)-1-hydroxyl-1,1-ethylidenediphosphonic acid, pyedpH4 = (2-(pyridin-4-yl)ethene-1,1-diyl)diphosphonic acid) were synthesized under hydrothermal conditions. Compounds 1 and 2 are isostructural and have ladder-like chain structures in which the {M2((μ - O )2)}(M = Zn , Cd ) dimer units are connected by O - P - O bridges. Compound 3 shows a unique type of double chain structure, in which the adjacent { Pb 2(μ - O )2} dimers are bridged by O - P - O and O - P - C - O groups into a chain. Compound 4 has a 2D structure, where the vertex-shared { PbO 5} polyhedra are connected by { CPO 3} tetrahedra through corner-sharing. The photoluminescence properties of compounds 1-4 were studied. Their potential as soft-oxometalate precursors is also discussed.