MFM-300(Sc) was explored as a catalyst for the gas-phase hydrogenation of acetone. The catalysis results support the presence of non-permanent open Sc(III) sites within the structure due to the requirement...
Metal–organic
frameworks have developed into a formidable
heterogeneous catalysis platform in recent years. It is well established
that thermolysis of coordinated solvents from MOF nodes can render
highly reactive, coordinatively unsaturated metal complexes which
are stabilized via site isolation and serve as active sites in catalysis.
Such approaches are limited to frameworks featuring solvated transition-metal
complexes and must be stable toward the formation of “permanent”
open metal sites. Herein, we exploit the hemilability of metal–carboxylate
bonds to generate transient open metal sites in an In(III) MOF, pertinent
to In-centered catalysis. The transient open metal sites catalyze
the Strecker reaction over multiple cycles without loss of activity
or crystallinity. We employ computational and spectroscopic methods
to confirm the formation of open metal sites via transient dissociation
of In(III)–carboxylate bonds. Furthermore, the amount of transient
open metal sites within the material and thus the catalytic performance
can be temperature-modulated.
Uncommon reversible guest-induced metalhemilabile linker bond dynamics in MOF MFM-300(Sc) was unraveled to switch on/switch off catalytic open metal sites. The catalytic activity of this MOF with nonpermanent open metal sites was demonstrated using a model Strecker hydrocyanation reaction as a proof-ofconcept. Conclusively, the catalytic activity was evidenced to be fully reversible, preserving the conversion performance and structure integrity of MFM-300(Sc) over multiple cycles. These experimental findings were corroborated by quantum-calculations that revealed a reaction mechanism driven by the Sc-open metal sites. This discovery paves the way towards the design of new effective and easily regenerable heterogeneous MOF catalysts integrating switchable metal sites.
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