3D metal-organic frameworks constructed of 2D metal aromatic sulfonate-carboxylate layers and 1,3-di(4-pyridyl)propane pillars: syntheses, structural topologies, and luminescent properties

Two metal-organic frameworks {[Zn-2(DSBDC)(dpp)(2)](H2O)(2)}(n) (1) (H4DSBDC = 2,5-disulfonylterephthalate acid and dpp = 1,3-di(4-pyridyl)propane) and [Cd-2(SBTC)(dpp)(1.5)](n) (2) (H4SBTC = 5-sulfonyl-1,2,4-benzenetricarboxylic acid) with novel sulfonate-carboxylate ligands have been synthesized and structurally characterized. The in situ formation of the H4DSBDC ligand derived from H4SBTC is unprecedented and involves a fundamentally new substitution of sulfonate for carboxylate in the in situ ligand synthesis reaction. The solid state structures of 1 and 2 consist of neutral 2D metal aromatic sulfonate-carboxylate layers, which are pillared by the dpp ligands to generate different 3D architectures. The topological structure of 1 is a trinodal net based on three kinds of topologically equivalent 4-connected nodes with the Schlafli symbol of (6(4).8(2)). The framework of 2 can be classified as a 4,5,6-connected 3D net with the Schlafli symbol of (4(3).6(3)) (4(3).6(5).8(2)) (4(6).6(6).8(3)). In the solid state, compounds 1 and 2 exhibit white-ish and blue photoluminescences, respectively.