Syntheses, Structures, and Properties of Silver–Organic Frameworks Constructed with 1,1′-Biphenyl-2,2′,6,6′-tetracarboxylic Acid

Abstract

The reactions of 1,1′-biphenyl-2,2′,6,6′-tetracarboxylic acid (H4bptc), N-containing auxiliary ligand, with different silver(I) salts under hydrothermal or solvent evaporation conditions yielded five unusual complexes with distinct structural features: {[Ag4(bptc)(bpy)4(H2O)]·(H2O)12}n (1), {[Ag1.5(bptc)0.5(bpy)1.5]·(NH4)0.5·(H2O)3}n (2), {[Ag2(H2bptc)(bpy)2]·(H2O)2}n (3), {[Ag2(H2bptc)(bpy)2]·(HClO4)}n (4), and {[Ag(H2bptc)0.5(bpe)]·(H2O)2}n (5) (bpy = 4,4′-bipyridine, bpe = 1,2-bis(4-pyridyl)ethene). Complexes 1–3 and 5 exhibit two-dimensional (2D) layer, and such layers are further united together to generate three-dimensional supramolecular structure through hydrogen bonding and π···π interactions, respectively. In complexes 1 and 2, butterfly shaped 16-membered water ring and infinite water tape are obtained, respectively. Both compounds 4 and 5 are 2-fold interpenetrated 3D frameworks. Complex 4 shows channels along the c axis that are occupied by the perchloric acid molecules. Different from robust 4, the 3D supramolecular architecture of 5 is based on the formation of hydrogen bonding between (H2O)4 cluster and the adjacent layers. In addition, the thermogravimetric analysis, powder X-ray diffraction (XRD), and photoluminescent behavior of the complexes have also been investigated.