Recent advancements in the development of photo- and electro-active hydrogen-bonded organic frameworks

The development of hydrogen-bonded organic frameworks (HOFs) with predictable topologies and robust structures for targeted functionality was initially hindered by the relatively weak H-bonding interactions as many HOFs would collapse upon guest solvent removal. Recently, the design of tectons with large pi-conjugated systems that form intermolecular shape-fitted pi-pi stacking interactions has proven to be an effective strategy to create chemically and thermally stable HOFs. More importantly, these HOFs with large pi-conjugated tectons exhibit accelerated redox hopping processes due to more favorable through-space orbital overlap interactions. These intrinsic photoelectric properties render HOFs an appealing and unique class of photoactive and electroactive porous materials for catalysis, sensing, and biomedical applications. Based on shape-fitted pi-pi stacking strategy, various robust photoactive and electroactive HOFs have been built from tectons containing both photosensitive or redox-active organic cores and hydrogen bonding sites. This review summarizes the recent advancements, including synthetic methods and diverse applications, in the development of photo- and electro-active HOFs. Considering the numerous photo- and electro-active organic units available, as well as the virtually unlimited potential combinations of organic cores and hydrogen bonding sites, we anticipate that this review will inspire scientists in a range of disciplines, ranging from porous materials to organic photoelectric materials and catalysis scientists, to further explore functional photo- and electro-active HOF materials.