Cyclic Trinuclear Units Based Covalent Metal-Organic Frameworks for Gold Recovery.

The development of porous solids for gold recovery is highly desired from both an economical and environmental point of view; however, the design of solid adsorbents with high overall performance is still challenging. Herein, we designed three copper(I) cyclic trinuclear units, Cu(I)-CTUs, based covalent metal-organic frameworks (CMOFs) by networking metal clusters with dynamic covalent linkages. These CMOFs deliver a high gold adsorption capacity of 3687 mg g, ultra-fast adsorption kinetics (i.e., removal efficiency > 99% within 20 s), excellent selectivity and reusability. In addition, they can be readily used for gold extraction from e-waste. Owing to the rich redox properties of Cu-CTUs, these CMOFs show three sorption mechanisms including adsorption, chemical reduction and photocatalytic reduction. Interestingly, the gold-loaded CMOFs can be used as catalysts for hydration of alkynes to ketones with high yields (e.g., up to ∼ 95% for 6 examples).