Ionic Organic Cage-encapsulating Phase-transferable Metal Clusters

TL;DR

This paper introduces a method to encapsulate small noble metal clusters inside ionic organic cages, enabling reversible transfer between aqueous and oil phases without size change, and creating recyclable catalysts.

Contribution

It presents a novel physical confinement approach using ionic organic cages for phase-transferable metal clusters, avoiding size perturbation common in ligand-based methods.

Findings

Reversible transfer of metal clusters between phases without size change

High catalytic activity of MC@I-Cage hybrids in liquid-phase reactions

Recyclability and switchability of the catalytic system

Abstract

Exploration of metal clusters (MCs) adaptive to both aqueous and oil phases without disturbing their size is promising for a broad scope of applications. The state-of-the-art approach via ligand-binding may perturb MC size due to varied metal-ligand binding strength when shuttling between solvents of different polarity. Herein, we applied physical confinement of a series of small noble MCs (less than 1 nm) inside ionic organic cages (I-Cages), which by means of anion exchange enables reversible transfer of MCs between aqueous and hydrophobic solutions without varying their ultrasmall size. Moreover, the MCs(at)I-Cage hybrid serves as a recyclable, reaction-switchable catalyst featuring high activity in liquid-phase catalysis.