In situ synthesis of ultrafine metal clusters triggered by dodecaborate supramolecular organic frameworks

Abstract

Supramolecular nano-assemblies with tunable morphology have attracted extensive attention in composite material manufacturing and many other fields. Herein, a new class of shape-controlled dodecaborate-based supramolecular organic frameworks (BOFs), decorated with diverse ultrafine noble metal clusters (Au, Pd, Pt, Ag), has been successfully fabricated via the tunable host–guest assembly of cucurbit[n = 5,6,7,8]uril and Cs₂[closo-B₁₂H₁₂]. Due to the unique dodecaborate-cucurbit[n]uril chaotropic effect, a breakthrough has been made in modulating the supramolecular frameworks in the urchin-like, network-like or octahedron-like structures without tedious chemical modifications or additional additives. More interestingly, Cs₂[closo-B₁₂H₁₂], a prominent component in supramolecular structures, can also play dual roles as an excellent reductant and capping agent for the formation of metal clusters. The final product, i.e., BOFs decorated with ultrafine metal clusters (metal/BOFs) can be precipitated from aqueous solutions rapidly and they show high catalytic activity and recyclability in Suzuki reactions and in the selective reduction of furfural (FAL) to furfuryl alcohol (FOL).