Hydrothermal synthesis, crystal structures and photoluminescent properties of four cadmium(II) coordination polymers derived from diphenic acid and auxiliary ligands

Four novel metal coordination polymers, [Cd(dpa)(H2O)]n (1), [Cd(dpa)(2,2′-bipy)]n (2), {[Cd2(dpa)2(4,4′-bipy)3](4,4′-bipy)(H2O)2}n (3) and [Cd(dpa)(bim)2(H2O)]}n (4) (H2dpa = 2,4′-biphenyl-dicarboxylic acid, 2,2′-bipy = 2,2′-bipyridine, 4,4′-bipy = 4,4′-bipyridine, bim = benzimidazole), have been synthesized and structurally characterized by elemental analysis, IR and X-ray diffraction. Single-crystal X-ray analyses reveal that the 2,4′-diphenic acids acts as bridging ligands, exhibiting rich coordination modes to link metal ions: bis-monodentate, bidentate chelating, chelating/bridging, monoatomic bridging and monodentate modes. In addition, the luminescent properties for compound 1–4 are also investigated in this work.

Graphical abstractFour new metal coordination polymers have been synthesized and structurally characterized. These coordination polymers have different architecture, such as 1-D helical structure, 2-D layer structure and 2-D microporous structure. Additionally, hydrogen bonding interactions and π–π stacking are found in some structures to further extend or stabilize the coordination motifs.Figure optionsDownload full-size imageDownload as PowerPoint slide