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

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.