A Cobalt Tandem Catalyst Supported on a Compressible Microporous Polymer Monolith

A compressible microporous polymer monolith (MPM) was prepared by performing the Sonogashira-Hagihara reaction between 1,4-diiodobenzene and 1,3,5-triethynylbenzene in a gel state without stirring. MPM was functionalized via the click reaction with 1,3,5-tris(azidomethyl)-2,4,6-trimethylbenzene and 2,6-diethynylpyridine. MPM showed superhydrophobicity but became hydrophilic after the click reaction. The functionalized MPM (F-MPM) had polar triazole groups generated by the click reaction, which were used as coordination sites for Co(II) ions. Cobalt nanoparticles were loaded to F-MPM through in situ reduction of coordinated Co(II) ions to produce a monolithic Co heterogeneous catalyst (Co-MPM). The microscopic study showed that MPM, F-MPM, and Co-MPM consisted of fiber bundles, together with spherical particles on the micrometer scale. Co-MPM was used for tandem catalysis. Co-MPM promoted the reaction of dehydrogenation of ammonia borane and hydrogenation of nitro compounds in one pot to give amine products. The reactions with the compression and release process were much faster compared with the reactions performed under the stirring conditions, suggesting that the repeated compression and release facilitated interfacial contact between the reactants and active sites in Co-MPM.