In Situ Carboxylate-Functionalized {Mo12O38}4–-Based Three-Dimensional Supramolecular Framework as a Copper-Triggered Heterogeneous Catalyst for Alkene Oxidation

It is of great research value to develop an efficient and stable catalyst that can achieve the oxidation of alkenes to obtain epoxides, which can serve as a multifunctional intermediate with important commercial value. Based on this, a three-dimensional (3D) supramolecular framework H[Cu^I(H₃bdcbpy)₂(Mo₁₂O₃₈)(H₂O)] (1, H₄bdcbpy·2Cl = N,N'-bis(3,5-dicarboxybenzyl-4,4'-bipyridine·dichloride) was obtained from carboxylate-functionalized 1D coordination polymers, which were derived from an unusual in situ [Mo₁₂O₃₈]^4- cluster and Cu-electron-deficient carboxylate complex units. The catalytic performance of 1 in the epoxidation of alkenes using TBHP was examined, revealing its remarkable efficiency in the conversion of cis-cyclooctene, with a high conversion rate of 99% and an outstanding selectivity of 100%. Complex 1 exhibited higher catalytic activity than the unmodified H₄bdcbpy·2Cl, CuCl₂·2H₂O, and Na₂MoO₄·2H₂O, as well as the most previously reported polyoxometalate (POM)-based metal-organic complexes (POMOCs). Moreover, the reaction kinetics and mechanism of the catalytic reaction were explored using free radical trapping experiments and control experiments. The stability of catalyst 1 was also investigated.