Efficient Mechanochemical Synthesis of Polyoxometalate⊂ZIF Complexes as Reusable Catalysts for Highly Selective Oxidation

Abstract

One-pot mechanochemical synthesis was demonstrated to be an efficient strategy to synthesize host-guest POM⊂rho-ZIF complexes (POM = polyoxometalate; rho-ZIF = zeolitic imidazolate framework with rho topology) with high crystallinity. In this work, the metastable rho-ZIF with large interior cavities and windows was used as host matrix for encapsulating and immobilizing bulky guest molecules with high loading efficiency and chemical stability. As novel catalysts, POM⊂rho-ZIF complexes were found effective for the selective oxidation of a series of sulfides to sulfoxides. Moreover, the heterogeneity of these composite catalysts was confirmed by leaching tests, and they can be recycled at least four times without significant loss of activity.

A Keggin Polyoxometalate Shows Water Oxidation Activity at Neutral pH: POM@ZIF‐8, an Efficient and Robust Electrocatalyst

“…[54][55][56][57] Ad irect comparison with the earlier reports of Keggin-catalyzed oxidation of organic substrates also encouraged us for such al ogical consideration. [58][59][60][61][62][63][64] As the organic molecules cannot come close to the central Xof[XM 12 O 40 ] nÀ (owing to large size), they should be attached with the surface for facile catalytic reaction. Thus,in case of WO catalysis by POM@ZIF-8, water can be considered to get associated (mostly,byHydrogen bond formation) with the Keggin surface.S uch association will allow facile electron transport between Keggin and water molecule.…”

Applications of inorganic‐organic hybrid architectures based on polyoxometalates in catalyzed and photocatalyzed chemical transformations

“…In a novel strategy, via a one‐pot mechanochemical synthesis, zeolitic imidazolate frameworks with rho topology ( rho ‐ZIF) and large interior cavities and windows was used as host matrix for encapsulating and immobilization of vanadium‐substituted Keggin‐type POMs with high loading efficiency and chemical stability (Figure ) . As the novel catalysts, PMoV⊂ rho ‐ZIFs were found being effective catalyst for selective oxidation of a series of sulfides to sulfoxides or sulfones, including bulky diphenyl sulfides.…”

“…The structural representation of PMoV ⊂ rho‐ZIF. Figure reproduced from Ref., with permission of the copyright holders…”

Cobalt based functional inorganic materials: Electrocatalytic water oxidation

“…In spite of no direct bonding of the substrate organic moiety with the true catalytic center i.e., the cobalt center, the reaction (e.g., oxidation/reduction reactions of the organic substrate) proceeds successfully. 69,70 Similarly, in case of Keggin-catalyzed water oxidation, a parallel mechanism can be feasible without disturbing the tetrahedral disposition of the central cobalt. Such association can allow facile electron transport between Keggin and water molecules.…”