Cadmium(II) and zinc(II) coordination polymers with mixed building blocks of benzenedicarboxyl and 2,5-bipyridyl-1,3,4-oxadiazole: Syntheses, crystal structures, and properties

Three Cd(II) and Zn(II) coordination polymers, including {[Cd(3-bpo)(mip)(H2O)](H2O)2}n (1), {[Cd(4-bpo)(hip)(H2O)](H2O)4}n (2), and {[Zn(4-bpo)(tp)](CH3OH)}n (3) were synthesized from the reactions of CdII or ZnII nitrate with mixed organic ligands [3-bpo = 2,5-bis(3-pyridyl)-1,3,4-oxadiazole, H2mip = 5-methylisophthalic acid, 4-bpo = 2,5-bis(4-pyridyl)-1,3,4-oxadiazole, H2hip = 5-hydroxylisophthalic acid, H2tp = terephthalic acid] under the similar layered diffusion condition. The resulting crystalline materials 1–3 were characterized by IR, microanalysis, powder X-ray diffraction (PXRD) techniques. Single-crystal X-ray diffraction indicates a 1-D tubular motif for 1, a 1-D dual-track array for 2, and a 2-D grid-like pattern for 3, constructed via different metal–ligand coordination contacts. Higher-dimensional supramolecular architectures are further assembled in 1–3 via H-bonding and aromatic stacking interactions. In addition, thermal stability and fluorescence of these polymeric complexes were also investigated and discussed.