Modulated Self-Assembly of Catalytically Active Metal-Organic Nanosheets Containing Zr6 Clusters and Dicarboxylate Ligands.

Abstract

Two-dimensional metal-organic nanosheets (MONs) have emerged as attractive alternatives to their three-dimensional metal-organic framework (MOF) counterparts for heterogeneous catalysis due to their greater external surface areas and higher accessibility of catalytically active sites. Zr MONs are particularly prized because of their chemical stability and high Lewis and Brønsted acidities of the Zr clusters. Herein, we show that careful control over modulated self-assembly and exfoliation conditions allows the isolation of the first example of a two-dimensional nanosheet wherein Zr6 clusters are linked by dicarboxylate ligands. The hxl topology MOF, termed GUF-14 (GUF = Glasgow University Framework), can be exfoliated into monolayer thickness hns topology MONs, and acid-induced removal of capping modulator units yields MONs with enhanced catalytic activity toward the formation of imines and the hydrolysis of an organophosphate nerve agent mimic. The discovery of GUF-14 serves as a valuable example of the undiscovered MOF/MON structural diversity extant in established metal-ligand systems that can be accessed by harnessing the power of modulated self-assembly protocols.