Formation of Three New Silver(I) Coordination Polymers Involving 1,2-Phenylenediacetic Acid via the Modulation of Dipyridyl-Containing Ligands

Three new silver(I) metal−organic frameworks (MOFs), namely, [Ag2(pda)(bipy)2]n·4nH2O (1), [Ag2(pda)(dpe)2(H2O)]n·4nH2O (2), and [Ag(Hpda)(bpp)]n (3), were prepared by hydrothermal reactions of silver(I) acetate with H2pda (H2pda = 1,2-phenylenediacetic acid) in the presence of different pyridyl-containing ligands (bipy = 4,4′-bipyridine, dpe = 1,2-di(4-pyridyl)-ethylene, and bpp = 1,2-bis(4-pyridyl)propane) and structurally characterized by single crystal X-ray diffraction. Complex 1 shows a two-dimensional (2D) four-connected network with a long topological vertex Schläfli symbol (4.62.4.63.64.6). Of particular interest, a new unreported octameric water cluster, (H2O)8, which is comprised of a cyclic water tetramer and four dangling water monomers, exists in 1. And the pseudorotaxane motifs are formed by these octameric clusters and the [Ag8(pda)2(bipy)4] loops. Complex 2 features a one-dimensional (1D) ladder-like chain structure, and the 2D networks, assembling by the combination of the pentameric water cluster, (H2O)5, and pda dianions, are supported by the 1D polymeric chains to form an infinite three-dimensional (3D) supramolecular framework. Complex 3 is a highly puckered 2D (6,3) sheet and further stacks via hydrogen bonding interlocks notated as R22 (18) to afford a unique 3D 66 topology with a long topological vertex Schläfli symbol of (6.62.6.62.6.62) but which is not a typical diamondoid network. The diverse arrangements of the complexes show the remarkable sensitivity of the AgI−H2pda system to the different dipyridyl ligands; that is to say, the subtle modulation of dipyridyl-containing ligand has a significant effect on the overall MOFs and the coordination modes of H2pda ligands. In addition, the properties of thermogravimetric analysis−differential scanning calorimetry, X-ray powder diffraction, and photoluminescent behaviors of the complexes have been also discussed.