Issue 5, 2022

Metal-hydrogen-pi-bonded organic frameworks


We report the synthesis and characterization of a new series of permanently porous, three-dimensional metal–organic frameworks (MOFs), M-HAF-2 (M = Fe, Ga, or In), constructed from tetratopic, hydroxamate-based, chelating linkers. The structure of M-HAF-2 was determined by three-dimensional electron diffraction (3D ED), revealing a unique interpenetrated hcb-a net topology. This unusual topology is enabled by the presence of free hydroxamic acid groups, which lead to the formation of a diverse network of cooperative interactions comprising metal–hydroxamate coordination interactions at single metal nodes, staggered π–π interactions between linkers, and H-bonding interactions between metal-coordinated and free hydroxamate groups. Such extensive, multimodal interconnectivity is reminiscent of the complex, noncovalent interaction networks of proteins and endows M-HAF-2 frameworks with high thermal and chemical stability and allows them to readily undergo postsynthetic metal ion exchange (PSE) between trivalent metal ions. We demonstrate that M-HAF-2 can serve as versatile porous materials for ionic separations, aided by one-dimensional channels lined by continuously π-stacked aromatic groups and H-bonding hydroxamate functionalities. As an addition to the small group of hydroxamic acid-based MOFs, M-HAF-2 represents a structural merger between MOFs and hydrogen-bonded organic frameworks (HOFs) and illustrates the utility of non-canonical metal-coordinating functionalities in the discovery of new bonding and topological patterns in reticular materials.

Graphical abstract: Metal-hydrogen-pi-bonded organic frameworks

Supplementary files

Article information

Article type
20 Dec 2021
05 Jan 2022
First published
05 Jan 2022

Dalton Trans., 2022,51, 1927-1935

Author version available

Metal-hydrogen-pi-bonded organic frameworks

J. Zhu, L. Samperisi, M. Kalaj, J. A. Chiong, J. B. Bailey, Z. Zhang, C. Yu, R. E. Sikma, X. Zou, S. M. Cohen, Z. Huang and F. A. Tezcan, Dalton Trans., 2022, 51, 1927 DOI: 10.1039/D1DT04278E

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