Comparing the Structures of Two Allomorphic Polyoxotungstates and the Difference in Weak Interactions by Thermal-dependent 2D-COS IR to Identify

A three-dimensional (3D) Keggin-type heteropolytimgstate{Zn(phen)(3)}(3)[ZnW12O40]center dot 9H(2)O 1 (phen = 1,10-phenanthroline) has been synthesized through a conventional hydrothermal synthesis and was characterized by X-ray single-crystal diffraction analysis, X-ray powder diffraction (XRD), IR, UV-DRS, thermogravimetric analysis (TGA), thermal-dependent 2D-IR correlation spectroscopy (2D-COS IR) and Raman spectrum. Crystal data for compound 1: trigonal system, space group R3 with a = b = 25.268(4), c = 17.462(5) angstrom, gamma = 120 degrees, V= 9655(4) angstrom(3) and Z = 3. Compound 1 is allomorphic to {Co(phen)(3)}(3)[CoW12O40]center dot 9H(2)O 2, which has been reported by Feng Chai et al. In compound 2, its prominent feature is that the decisive role of water molecules (O-H center dot center dot center dot O) builds a 3D supramolecular structure. However, in the structure of compound 1, the interlayer space is filled by Zn(phen)(3)](2+) cations which linked the layers via C-H center dot center dot center dot O hydrogen bonding interactions to construct a three-dimensional framework. Two compounds are different in weak interactions, so we identify them by Thermal-dependent 2D-COS IR. Moreover, the fluorescence of compound 1 was also described.