Synthesis, crystal structure and optical properties of a novel 1D coordination polymer [Zn3(C7H2NO5)2·8(H2O)]n

The reaction of Zn(II) ions and chelidamic acid (2,6-dicarboxy-4-hydroxypyridine) gave a novel 1D coordination polymer, [Zn3(C7H2NO5)2·8(H2O)]n (1), which are characterized by X-ray single crystal diffraction. The crystal structure of 1 reveals that Zn(II) centers are linked via chelidamic acid to form one-dimensional chains, further linked by hydrogen bonds to form a 3-D network. The optical properties were investigated in terms of diffuse reflectance and fluorescent spectra, which exhibit strong green luminescence. The electronic band structure along with the density of states (DOS) calculated by the DFT method indicate that compound 1 is a semiconductor and that the origin of the emission band may be mainly ascribed to ligand-to-ligand charge transfer (LLCT) where the electrons are transferred from the O-2p to C-2p states.