Hydrogen-bonded organic frameworks (HOFs) from design to environmental application

Hydrogen-bonded organic frameworks (HOFs) are a rapidly emerging class of porous materials that exhibit several desirable features, including tunable porosity, flexibility, and mild synthesis conditions. These frameworks are characterized by metal-free chemical compositions, cost-effectiveness, and ease of regeneration, making them suitable for a wide range of environmental applications. However, their practical utility is often constrained by the inherent instability of their frameworks due to the weak and reversible nature of hydrogen bonds. This review explores the fundamental aspects of hydrogen bond formation and the synthesis methods of HOFs, providing an in-depth categorization of their structural design concepts, such as pi-pi stacking, chargeassisted hydrogen bonding, and interpenetration strategies, aimed at enhancing their stability. Moreover, the review highlights key advancements in the application of HOFs for environmental remediation, including radionuclide removal, heavy metal adsorption, dye degradation, and the capture of hazardous gases like iodine. These specific applications demonstrate the growing potential of HOFs in addressing critical environmental challenges. Finally, we discuss current limitations, opportunities for enhancing framework stability, and future directions for expanding the use of HOFs in environmental technologies.