Hydrogen-bonded organic frameworks: Toward adaptive porous materials for energy, environment, and smart devices

Hydrogen-bonded organic frameworks (HOFs) have recognized as a member of the porous crystalline material's family that placed between the conventional inorganic solids and the covalent and/or coordination-based organic frameworks. They are assembled by directional hydrogen bonds, which are frequently strengthened by п-п stacking and van der Waals force, offering high crystallinity, adjustable porosity, flexibility and self-repairing properties, properties that are uncommon in MOFs and COFs. This review highlights the overview of the HOFs with the basic design principles, hydrogen-bond construction, and various types of supramolecular synthons, along with the different methods of synthesis. Rational design, heterojunction formation with other suitable materials, and the incorporation of metal-ions further enhanced the functionality of HOFs. This article also covers the wide range of uses of HOFs, including energy technologies (e.g., electrochemical energy storage, energy conversion, solar fuel generation), environmental related applications (pollutant adsorption, fluorescence sensing, chiral and molecular recognition and degradation/transformation of pollutants). HOFs also show potential uses in bioenvironmental applications, conductive devices, such as memristors, neuromorphic devices, and artificial sensory devices. Finally, the review also highlights existing limitations, such as stability of the framework, charge transport and understanding of the underlying mechanism and provide valuable insights on overcoming these drawbacks.