Water-mediated synthesis of hydrogen-bonded metal–organic frameworks

TL;DR

This paper introduces a new class of materials combining metal–organic and hydrogen-bonded frameworks using water in the synthesis process.

Contribution

A water-mediated strategy to synthesize hydrogen-bonded metal–organic frameworks (H-MOFs) by integrating MOFs and HOFs.

Findings

NNM-1(Cu) can adsorb 4.84 mmol g−1 of NH3 under low pressure, showing potential for ammonia capture.

Hydrogen-bonded pillars with R22(8) motifs form between metal–organic layers in NNM-1 structures.

Water is essential for the structural transformation from 3D MOFs to H-MOFs.

Abstract

The integration of different types of frameworks into one would provide a unique opportunity for the development of crystalline frameworks that can combine the unique advantages of each. In this work, we successfully realize the integration of metal–organic frameworks (MOFs) and hydrogen-bonded organic frameworks (HOFs) through the synthesis of two hydrogen-bonded metal–organic frameworks, namely NNM-1(M) (M = Cu or Ni). The structures of NNM-1 are built on (4, 4)-squared coordinative metal–organic layers. Between the layers, two adjacent protonated carboxylic groups serve as both hydrogen donors and acceptors, leading to the formation of hydrogen-bonded pillars with R22(8) dimeric hydrogen bonding, the most common hydrogen-bonded motif in HOFs. It was found that water plays a vital role in the structural transformation from 3D MOFs to H-MOFs here. Under a low pressure of 0.1 bar, the material NNM-1(Cu) can adsorb 4.84 mmol g−1 of NH3, making it a promising adsorbent for ammonia capture.

In this work, we have reported the creation of a new family of materials with the integration of MOFs and HOFs into H-MOFs through a water-mediated synthetic strategy.

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