Hydrogen-bonded organic frameworks: Chemistry and functions

Abstract

<h2>Summary</h2> The study of hydrogen-bonding (H-bonding) interactions can be traced back to over a century ago. Recent practices on H-bonding chemistry for constructing extended frameworks have led to the emergence of hydrogen-bonded organic frameworks (HOFs). Rational combinations of molecular skeletons and hydrogen-bonded units result in HOFs with porosity or flexibility. HOF structures might be predicted through framework topology and tuned by adjusting linker lengths for getting isostructural HOFs, although there are some HOFs showing responsive flexibility for specific molecular recognitions. Besides, HOFs exhibit exceptional solution processability, easy healing, and purification. HOFs have thus been objects of extensive study over the past decade for diverse application scenarios, ranging from gas adsorption to catalysis, proton conduction, chemical sensing, and enzyme encapsulation. In this review, we not only outline the uniqueness and design principle of HOFs but also highlight the advances in both their structures and functions to promote this very important emerging topic.