Metal-Controlled Assembly of Coordination Polymers with the Flexible Ligand 1,1‘-Biphenyl-2,2‘-dicarboxylate Acid

To determine the influence of metal ions on the formation of metal−organic frameworks, five new coordination polymers, [Pb 6 (dpa) 4 O 2 ] n ( 1 ), [Ag 2 (dpa)] n ( 2 ), [Nd 2 (dpa) 3 (H 2 O) 2 ] n ( 3 ), [Zn(dpa)(H 2 O)] n ( 4 ), and [Cd 2 (dpa) 2 (phen) 2 (H 2 O) 2 ] n ( 5 ), have been hydrothermally synthesized from 1,1‘-biphenyl-2,2‘-dicarboxylate acid (dpa). Complex 1 is a one-dimensional chain structure constructed from a new building unit, Pb 6 O 18, which is connected by four different dpa molecules. Complex 3 is also a one-dimensional chain structure but is composed of a different building unit bridged by three dpa molecules. This complex is further extended into a two-dimensional supramolecular framework. Like complex 3, complex 4 is a two-dimensional supramolecular framework, which is connected by one-dimensional chains through π−π interactions and hydrogen bonding interactions. Complex 5 is a three-dimensional metal−organic supramolecular coordination polymer that possesses rectangular cavities. Different from the above four complexes, complex 2 is a two-dimensional covalence structure. To our knowledge, this is the first two-dimensional coordination polymer composed of metal ions and the dpa ligand. Furthermore, at room temperature, complex 4 exhibits strong photoluminescence.