Enzymatic catalysis has fueled considerable interest from chemists due to its high efficiency and selectivity. However, the structural complexity and vulnerability hamper the application potentials of enzymes. Driven by the practical demand for chemical conversion, there is a long-sought quest for bioinspired catalysts reproducing and even surpassing the functions of natural enzymes. As nanoporous materials with high surface areas and crystallinity, metal-organic frameworks (MOFs) represent an exquisite case of how natural enzymes and their active sites are integrated into porous solids, affording bioinspired heterogeneous catalysts with superior stability and customizable structures. In this review, we comprehensively summarize the advances of bioinspired MOFs for catalysis, discuss the design principle of various MOF-based catalysts, such as MOF-enzyme composites and MOFs embedded with active sites, and explore the utility of these catalysts in different reactions. The advantages of MOFs as enzyme mimetics are also highlighted, including confinement, templating effects, and functionality, in comparison with homogeneous supramolecular catalysts. A perspective is provided to discuss potential solutions addressing current challenges in MOF catalysis.
Zeolites that prefer alkynes: Alkenes such as ethylene and propene must be separated from alkynes before they can be converted in polymers. Drawbacks in current methods, such as hydrogenation of alkynes producing unwanted alkanes, has spurred interest in sorption separation methods. Zeolites have generally been inefficient, given the similar sizes and volatilities of the molecules. Chai et al. incorporated atomically dispersed divalent transition metal cations into faujasite zeolite and found that the nickel-containing analog efficiently removed alkynes from olefins through chemoselective binding at open nickel(II) sites. At ambient conditions in the presence of water and carbon dioxide, the zeolites retained separation selectivities of 100 and 92, respectively, for acetylene over ethylene and propyne over propylene for 10 adsorption-desorption cycles. Science , this issue p. 1002