Abstract
Two new polyoxotungstates with dafo and 4,4′-bipy ligands, [Ag(dafo)2]2{[Ag(4,4′-bipy)]2SiW12O40} (1) and [Cd2(dafo)4(4, 4′-bipy)(H2O)2](dafo) SiW12O40 (2) (dafo = 4, 5-diazafluoren-9-one, 4,4′-bipy = 4,4′-bipyridine), have been hydrothermally synthesized and characterized by elemental analyses, IR, TG and single crystal X-ray diffraction. Compound 1 consists of a one-dimensional (1D) chain constructed from [Ag(4,4′-bipy)]+ cations. With the connection of [Ag(4,4′-bipy)]+ cations and α-[SiW12O40]4− anions, two-dimensional (2D) structure was built. Because of the π–π stacking interactions between pyridyl rings of 4,4′-bipy from adjacent chains, three-dimensional (3D) structure was generated. Furthermore, the C–H ··· O weak interaction between and polytungstate made the structure more stable. Like 1, compound 2 is a three-dimensional (3D) supramolecular compound constructed from a transition-metal complex fragment [Cd2(dafo)4(4,4′-bipy)(H2O)2]4+,
and free dafo through C–H ··· O weak interactions. To our best knowledge, it is the first time that saturated Keggin-type polyoxotungstates interact with dafo and 4,4′-bipy at the same time.
Acknowledgements
The authors thank National Science Foundation of China (No. 20371011), Science and Technology Development Project Foundation of Jilin Province (No. 20060420), Analysis and testing foundation of Northeast Normal University (No. 201586000/201372000), Ph.D station Foundation of Ministry of Education (No. 20060200002) for financial support.