A new 2D terbium(III) coordination polymer involving in situ oxalate formation: Synthesis, X-ray structure and luminescent properties

A new 2D terbium coordination polymer, {[Tb2(6-hynic)2(ox)2(H2O)4]·(H2O)2}n (1) [6-hynic = 6-hydroxynicotinate, ox = oxalate], was prepared by hydrothermal synthesis and characterized by IR spectroscopy, elemental analysis, thermogravimetric analysis (TGA), powder X-ray diffraction and single-crystal X-ray diffraction. Two chelatively bridging oxalate moieties coordinating through four of their O atoms lead to the formation of zigzag Tb(III)-oxalate chains, two uniquely bridging anionic 6-hynic ligands which coordinate through two O centers altogether make the system take an overall two-dimensional network arrangement. Three-dimensional fluorescence spectra of 1 were detected at room temperature under the excitation and the emission wavelengths in the range of 420-750 nm with the interval of 5 nm. The lifetime of 1 in solid-state at room temperature up to 0.921 ms. On the other hand, poor luminescence efficiency has been noted for the Tb3+-6-hynic-ox complex.