Synthesis and catalytic activities of two new extended Preyssler-type tungstophosphates with different cavity centers

摘要

Two new extended Preyssler-type polyoxometalates (POMs) constructed by Fe(III), 2,2'-biimidazole and Preyssler-type tungstophosphate anions with Na and Ag cavity centers respectively, namely {(H(4)biim)(5)H[Fe(H(2)biim)(H2O)(2)(ZP(5)W(30)O(110))]center dot 17H(2)O}(n) (Z = Na, compound 1; Z = Ag, compound 2; H(2)biim = 2,2'-biimidazole), were designed and synthesized under hydrothermal conditions, and were systematically characterized by physico-chemical and spectroscopic methods. The two compounds are isostructural co-ordination polymers. In compound 1 or 2, there exists interesting infinite 1D chains composed of Preyssler-type [ZP(5)W(30)O(110)](14-) (abbreviated as {ZP(5)W(30)}) polyanions bridged by Fe(III)-complex fragments, and these chains further formed 3D supramolecular frameworks via extensive hydrogen-bonding interactions. Especially for compound 2, two types of transition metals, i.e. one Ag+ ion as a center in the inner cavity and two Fe3+ ions as modified cations on the outer surface of one {ZP(5)W(30)} unit, existed in the same compound. Additionally, the electrochemical behaviors and acid catalytic activities of compounds 1 and 2 have been investigated. (C) 2016 Elsevier B.V. All rights reserved.