Three new Cd(II)/Zn(II) coordination polymers assembled via dual-ligand strategy: crystal structures and luminescent properties

Dual-ligand strategy was used to synthesize three new coordination polymers with the formula as [Cd(HL)(2,2'-bipy)](n).n(H2O) (1), [Cd-3(L)(2)(bib)(3)(H2O)](n) (2), [Zn(HL)(2,2'-bipy)](n) (3) (H3L=biphenyl-3,4',5-tricarboxylic acid, 2,2'-bipy=2, 2'-bipyridine, bib=1,4-bis(imidazol-1-yl)butane), which were further structurally characterized by single crystal X-ray diffraction analyses. Compound 1 features a 1D infinite chain structure and pi horizontal ellipsis pi interactions between adjacent 1D chains gives rise to a 2D layer and further O-H horizontal ellipsis O hydrogen bonding interactions between adjacent 2D layers affords a 3D supramolecular framework. Compound 2 shows a 3D framework with unprecedented (3,4)-connected topology. Compound 3 features a 2D -> 3D interdigitated supramolecular framework based on 2D hydrogen-bonding layers that constructed from 1D infinite chain and interchain O-H horizontal ellipsis O hydrogen bonding interactions. Luminescence investigations revealed that compound 1 shows interesting tunable luminescence via altering the excitation wavelength, and compound 2-3 show intense unimodal emission luminescence at room temperature.