Recent progress in Gas Separation Platforms based on Hydrogen-Bonded Organic Frameworks (HOFs)

Hydrogen-bonded frameworks (HOFs) are a new and appealing class of porous crystalline materials that are constructed from organic moieties through hydrogen bonding. Because of the brittle character of hydrogen bonding and flexibility, HOFs have shown various benefits, including a favorably crystalline structure, solution processability, ease of purification, sufficient recyclability, and comparatively low stability and permanent porosity. The porosity and polymer solubility features of MOFs are combined in HOFs, which have remarkable advantages as membrane materials. In addition, solubility in organic solvents, the possibility of synthesis by solution processing method, easy scale-up, uniform channels, three-dimensional network, and a high degree of crystallinity with flexible and organized porosity structures, can all lead to the formation of a superior membrane. In particular, the dynamic structure of HOFs can alter in response to various stimuli, resulting in modified gas permeation. This is made possible by the effect of guest molecules and hydrogen bond flexibility. In this work, the prominent HOFs that have been successfully used in the gas adsorption process are studied and the principles of designing and achieving suitable structures for this purpose are examined. On the other hand, in this review, significant information on the cause of stability and application of HOFs is reported. Eventually, the prospective future of HOFs for gas separation is also highlighted, and potential research areas are proposed.