Polyoxometalate-Based Metal–Organic Frameworks for Selective Oxidation of Aryl Alkenes to Aldehydes

Abstract

Polyoxometalates (POMs) show considerable catalytic performance toward the selective oxidation of alkenes to aldehydes, which is commercially valuable for the production of pharmaceuticals, dyes, perfumes, and fine chemicals. However, the low specific surface area of POMs as heterogeneous catalysts and poor recyclability as homogeneous catalysts have hindered their wide application. Dispersing POMs into metal-organic frameworks (MOFs) for the construction of POM-based MOFs (POMOFs) suggests a promising strategy to realize the homogeneity of heterogeneous catalysis. Herein, we report two new POMOFs with chemical formulas of [Co(BBTZ)][HBWO]·10HO (1) and [Co(HO)(BBTZ)][BWO]·NO·4HO (2) (BBTZ = 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene) for the selective oxidation of alkenes to aldehydes. Compound 1 possesses a non-interpenetrated three-dimensional (3D) cds-type open framework with a 3D channel system. Compound 2 displays a 3D polyrotaxane framework with one-dimensional channels along the [100] direction. In the selective oxidation of styrene into benzaldehyde, compound 1 can achieve a 100% conversion in 4 h with 96% selectivity toward benzaldehyde, which is superior to that of compound 2. A series of control experiments reveal that the co-role of [BWO] and Co active center as well as a more open framework feature co-promote the catalytic property of the POMOFs in this case. This work may suggest a new option for the development of POMOF catalysts in the selective oxidation of alkenes.

POM@MOF Hybrids: Synthesis and Applications

“…Recently, this group also prepared the PV2Mo10@NU-1000 catalyst by using the same method and the synthesized material showed a full conversion of CEES, with O2 as the oxidant. In addition to the well-known MOFs, several other POM@MOF hybrid materials, including [Co(BBPTZ)3][HPMo12O40]•24H2O and [Cu I 6(trz)6(PW12O40)2], have been synthesized and applied for ODS [88], the oxidation of aryl alkenes [89,90], alkylbenzenes [91], and alcohols [92] (see Table 2).…”

“…Accordingly, the ZIF-8@PW12 material was insoluble in hydrophilic solvents. The ZIF- [88], the oxidation of aryl alkenes [89,90], alkylbenzenes [91], and alcohols [92] (see Table 2).…”

Metal–Organic Frameworks Encapsulating Active Nanoparticles as Emerging Composites for Catalysis: Recent Progress and Perspectives

“…To further explore the capability of MOFs for catalysts, some catalytically active nanoparticles (NPs) such as noble metals, metal oxides, quantum dots, and polyoxometalates (POMs) are integrated with MOFs into a composite nanostructure . These nanocomposites have being attracted immense research interest in heterogeneous catalysis since the first report on Pd loading in MOF‐5(Zn) was made by Fischer et al in 2005, because they not only combine the properties of active NPs and MOFs but also bring the unique collective and synergetic functions in comparison with single‐component counterparts.…”

A Facile Grinding Method for the Synthesis of 3D Ag Metal–Organic Frameworks (MOFs) Containing Ag6Mo7O24 for High‐Performance Supercapacitors

“…Polyoxometalates (POMs) are early transition metal oxides with high anionic charge, oxygen‐rich surfaces, adjustable acidity, high thermal stability, and unique redox properties, which are widely used in the fields of catalysis, anti‐tumor activity, photochemistry, electrochemistry, energy and environment . Encouragingly, POMs are an ideal candidate for electrode materials owing to their multi‐electron transfer properties, also known as electronic storage or sponge properties.…”