A new ZnII coordination polymer based on 4-(pyridin-4-yl)benzoic and formic acids: in-situ synthesis, crystal structure and luminescence properties.

The title compound, poly[(μ2-formato-κ3O,O':O)[μ2-4-(pyridin-4-yl)benzoato-κ3N:O,O']zinc(II)], [Zn(C12H8NO2)(HCOO)]n, has been synthesized in situ and characterized by thermogravimetric analysis (TGA) and single-crystal and powder X-ray diffraction analyses. The polymer contains two independent structural units in the asymmetric unit. These are constructed from Zn2+ ions, 4-(pyridin-4-yl)benzoate (4-pbc) bridges and in-situ-generated formate ligands, forming two similar two-dimensional (2D) layer structures. These similar 2D layers are arranged alternately and are linked with each other by dense C-H...O hydrogen bonds to generate a three-dimensional (3D) supramolecular framework. The crystal is pseudomerohedrally twinned about [201]. Compared with free 4-Hpbc, the polymer exhibits a red shift and significantly enhanced solid-state luminescence properties.