Syntheses, Structures,\nand Properties of Silver–Organic\nFrameworks Constructed with 1,1′-Biphenyl-2,2′,6,6′-tetracarboxylic\nAcid

Abstract

The reactions of 1,1′-biphenyl-2,2′,6,6′-tetracarboxylic\nacid (H₄bptc), N-containing auxiliary ligand, with different\nsilver­(I) salts under hydrothermal or solvent evaporation conditions\nyielded five unusual complexes with distinct structural features:\n{[Ag₄(bptc)­(bpy)₄(H₂O)]·(H₂O)₁₂}_<i>n</i> (<b>1</b>), {[Ag_1.5(bptc)_0.5(bpy)_1.5]·(NH₄)_0.5·(H₂O)₃}_<i>n</i> (<b>2</b>), {[Ag₂(H₂bptc)­(bpy)₂]·(H₂O)₂}_<i>n</i> (<b>3</b>), {[Ag₂(H₂bptc)­(bpy)₂]·(HClO₄)}_<i>n</i> (<b>4</b>), and {[Ag­(H₂bptc)_0.5(bpe)]·(H₂O)₂}_<i>n</i> (<b>5</b>) (bpy = 4,4′-bipyridine, bpe = 1,2-bis­(4-pyridyl)­ethene).\nComplexes <b>1</b>–<b>3</b> and <b>5</b> exhibit\ntwo-dimensional (2D) layer, and such layers are further united together\nto generate three-dimensional supramolecular structure through hydrogen\nbonding and π···π interactions, respectively.\nIn complexes <b>1</b> and <b>2</b>, butterfly shaped 16-membered\nwater ring and infinite water tape are obtained, respectively. Both\ncompounds <b>4</b> and <b>5</b> are 2-fold interpenetrated\n3D frameworks. Complex <b>4</b> shows channels along the <i>c</i> axis that are occupied by the perchloric acid molecules.\nDifferent from robust <b>4</b>, the 3D supramolecular architecture\nof <b>5</b> is based on the formation of hydrogen bonding between\n(H₂O)₄ cluster and the adjacent layers. In addition,\nthe thermogravimetric analysis, powder X-ray diffraction (XRD), and\nphotoluminescent behavior of the complexes have also been investigated.