Highly Stable Catalysts with Adamantane Topology Based on a Mixed-Valence {V₁₆} Cluster for the Aerobic Epoxidation of Olefins

In this work, a highly stable heterogeneous catalyst with an adamantane topology was synthesized by loading a mixed-valence {V₁₆} cluster onto a metal-organic framework: H₃[Na(N₂C₆H₁₂)₂]₂[V₈^IVV₈^VO₃₈Cl]·3H₂O (NENU-MV-6). Nanoscale regulation of crystal morphology was achieved by modulating reaction solvents to influence nucleation and growth rates, yielding micronanocrystals (NENU-MV-6n) with a size distribution of around 500 nm. These crystals retain the tetrahedral morphology of NENU-MV-6 while exhibiting high thermal, acid-base, and solvent stability. Under oxygen-based oxidation conditions, NENU-MV-6n demonstrated excellent catalytic activity, selectivity, and universality toward olefin derivatives when used as a heterogeneous catalyst for olefin epoxidation. Furthermore, NENU-MV-6n exhibited outstanding cycling stability, showing no significant decline in catalytic activity after ten cycles. In summary, designing the structure and size of polyoxovanadate-based metal-organic frameworks (POV-MOFs) can effectively enhance catalyst stability and catalytic activity, providing new insights for the synthesis and nanoscale regulation of alkaline earth metal polyoxometalate hybrids.