Exploratory syntheses, structures, and photoluminescent properties of three lead multi-dimensional frameworks

Abstract

Three structurally diverse PbII coordination complexes, [Pb3O(OH)(4-sphth)]2(H2O) (1), [Pb(3,5-Hdhb)]H2O (2), and [Pb3(4-nphth)2(OH)2] (3) (4-H3sphth, 4-sulfophthalic acid; 3,5-H2dhb, 3,5-dihydroxybenzoic acid; 4-H2nphth, 4-nitrophthalic acid), were synthesized under hydrothermal conditions. X-ray diffraction analyses reveal that 1 is constructed from [Pb4O4] cubanes, based on which ladder-shaped structure is built via 4-H3sphth bridge. This is the first Pb4O4-containing polymer. The Pb2O2 units in 2 are bridged by two parallel 3,5-HDHB ligands along the a-axis and two other parallel 3,5-HDHB ligands along the b-axis, forming a 3-D framework. For 3, the crystal structure is built up of a layer motif consisting of corner-sharing pyramidal Pb3O units, which are linked through Pb corners to form a hexagonal unit. Each PbO6 polyhedron is connected to three polyhedra (Pb3O) via sharing an edge (two μ 3-oxygen atoms) and two faces (three μ 3-oxygen atoms), thus yielding an infinite 2-D Pb–O–Pb (3,6-net) honeycomb layer. The luminescence of 1–3 demonstrates that they may be good candidates for luminescent materials.