Mixed-ligand coordination polymers constructed from flexible 2,2′-biphenyldicarboxylate and rigid isomeric bipyridines

Six coordination polymers have been synthesized and characterized based on dpa and isomeric bipyridine mixed ligands with various metal ions. Complex 1 exhibits a two-dimensional layer structure. Complex 2 is isomorphic to complex 1, with only small differences in bond lengths and bond angles. Complex 3 shows a one-dimensional chain structure composed of interesting pentanuclear Co building units. Complex 4 possesses a two-dimensional (4, 4) layer network, which crystallizes in a homochiral space group. During the synthesis process of complex 4, the dpa ligands decompose and form 2-bpa ligands, which connect with Ni atoms and produce the two-dimensional complex 5. Complex 6 exhibits a three-dimensional supramolecular structural feature constructed from discrete building units with π–π interactions. Furthermore, the magnetic properties of complex 2 are studied.