The synthesis and characterization of the 3-D framework of SO42− supported Keplerate-type polyoxometalate

Abstract

We report a Keplerate-type polyoxometalate Na 18 K 8 [{Mo 6 O 21 (H 2 O) 3 (SO 4 )} 12 (Fe(H 2 O) 2 ) 30 ]·ca. 67 H 2 O ( 1 ), which is composed of 12 pentagonal {(Mo)Mo 5 } units and 30 [Fe(H 2 O) 2 ] 3+ linkers. This giant heterometal Keplerate-type cluster is supported by SO 4 2− and display interesting topologies, which are connected by two kinds of Na + cations (mononuclear and binuclear Na + cations) to form three-dimensional (3-D) open-framework. The compound was characterized by the elemental analysis, thermogravimetry, spectroscopic methods (IR and UV/Vis), bond valence sum (BVS) calculations, X-ray photoelectron spectroscopy (XPS) and single crystal X-ray structure analysis. The photocatalytic property of compound 1 has been investigated, which shows a good photocatalyst for the degradation of RhB. The Keplerate cluster is composed of 12 slightly domed (virtual C 5 v symmetry), {(Mo)Mo 5 } pentagonal units connected by 30 [Fe III (H 2 O)2] 3+ linker groups. The spherical shell encapsulates 12 heavily disordered tridentate sulfate groups. And the discrete polyanionic capsule contains 20 (Mo 3 Fe 3 O 6 ) pores, the eight close association of the K + ions and twelve Na + ions to the twenty {Mo 3 Fe 3 O 6 } hexagonal pores reminiscent of K + -specific and Na + -specific crown ethers respectively, and other Na + ions (mononuclear and binuclear Na + ions) play the part of linking the discrete capsules to the three-dimensional (3-D) open-framework. ► Supported by SO 4 2– . ► Displays interesting 3-D topologies. ► A good photocatalyst for degradation of RhB.