A two-dimensional framework with U-shaped Cu4I4 Cluster linked by semi-rigid ligand: Synthesis, crystal structure and Luminescent Properties

Abstract

A new two-dimensional coordination polymer with formula of Cu4I4(3-bpcd)2·C2H5OH·1.5CH3CN (1) (3-bpcd=N,N'-bis(pyridin-3-yl) cyclohexane-1,4-dicarboxamide), has been synthesized at room temperature and structurally characterized. Crystallography study shows that 1 contains Cu4I4 clusters, which geometry significantly different from reported those called “cubane”, “stairstep” and “fliggy octahedron”. The Cu4I4 clusters in the structure of 1 were connected by semi-rigid ligand (3-bpcd) to form a two dimensional layer (4, 4) net, while Cu4I4 clusters are regarded as 4-connected nodes. These layers further stack in an ABAB fashion and each layer connect by hydrogen bond to generate a three dimensional framework. Thermogravimetric analysis reveals that 1 processes high thermal stability up to about 320 °C. Powder X-ray diffraction analysis indicates that the framework of structure of 1 could be stable in water/ethanol. The luminescent properties study of 1 show that the fluorescence intensity decreased with increase of the concentration of metal ions. Further study indicated that 1 could be used as a fluorescent probe and has high selectively effect on Fe(III) ions in ethanol, as well as in water. [Display omitted]