A (4,4)-connected zinc(II) coordination polymer constructed with the flexible 2-carboxy phenoxyacetate ligand: synthesis, conformation alteration and fluorescent properties
Jun‐Xia Li, Tian Zhang, He-Jun Chen, Zhong‐Xiang Du
Abstract
Abstract A new binary Zn II coordination polymer, [Zn(2-cpa)(H 2 O)] n ( 2D-Zn ) has been prepared by a 120 °C hydrothermal reaction of zinc(II) sulfate heptahydrate and 2-carboxy phenoxyacetic acid (2-H 2 cpa) in the presence of potassium hydroxide. Single-crystal X-ray diffraction analysis shows that the Zn II ion is located in a deformed ZnO 6 octahedron bonded by one water and three 2-carboxy phenoxyacetate (2-cpa) ligands. The 2-cpa exhibits pentadentate double bridging chelate- μ 3 coordination mode and connects adjacent Zn II ions to generate a corrugated (4,4)-connected layer structure. The structures, conformation of 2-cpa and photoluminescence spectra for 2D-Zn have been carefully analyzed and compared with its two closely related compounds ̶ 1D [Zn(2-cpa)(H 2 O)] n ( 1D-Zn ) and mononuclear [Zn(2-cpa)(H 2 O) 3 ] ( 0D-Zn ). The results showed that the conformation of 2-cpa in 2D-Zn has the maximum alteration and the corresponding fluorescence emission peak of 2D-Zn has the largest red-shift of 62 nm compared with that of free 2-H 2 cpa.