Dialing in Catalytic Sites on Metal Organic Framework Nodes: MIL-53(Al) and MIL-68(Al) Probed with Methanol Dehydration Catalysis

Many metal organic frameworks (MOFs) incorporate metal oxide clusters as nodes. Node sites where linkers are missing can be catalytic sites. We now show how to dial in the number and occupancy of such sites in MIL-53 and MIL-68, which incorporate aluminum-oxide-like nodes. The methods involve modulators used in synthesis and postsynthesis reactions to control the modulator-derived groups on these sites. We illustrate the methods using formic acid as a modulator, giving formate ligands on the sites, and these can be removed to leave μ₂-OH groups and open Lewis acid sites. Methanol dehydration was used as a catalytic reaction to probe these sites, with infrared spectra giving evidence of methoxide ligands as reaction intermediates. Control of node surface chemistry opens the door for placement of a variety of ligands on a wide range of metal oxide cluster nodes for dialing in reactivity and catalytic properties of a potentially immense class of structurally well-defined materials.

In situ Raman and FTIR spectroscopic study on the formation of the isomers MIL-68(Al) and MIL-53(Al)

The paper describes a method to induce the formation of MIL-68(Al) rather than MIL-53(Al) using a formic acid modulated synthesis approach.

Retraction: Insight into the reversible structural crystalline-state transformation from MIL-53(Al) to MIL-68(Al)

Retraction of ‘Insight into the reversible structural crystalline-state transformation from MIL-53(Al) to MIL-68(Al)’ by Adelaida Perea-Cachero et al., CrystEngComm, 2018, 20, 402–406.

Enhanced photocatalytic H2 production of cadmium-free rGO-mediated ZnS/CuS heterojunction derived from a MOF

The MOF-templated porous ZnS/CuS heterojunction with rGO as the charge carrier mediator exhibits enhanced photocatalytic hydrogen production under visible light illumination.