Intermolecular Interactions Regulating Exciton Behavior in Hydrogen-Bonded Organic Framework for Photocatalytic...

Exciton effects play a vital role in photocatalytic reactions, yet their precise regulation remains highly challenging, as even subtle variations can lead to pronounced differences in exciton behavior. To date, the influence of intermolecular interactions on exciton dynamics remains largely unexplored. Herein, two isoreticular donor-acceptor hydrogen-bonded or ganic frameworks (D-A HOFs), PFC-19 and PFC-70, are synthesized. Notably, PFC-70's monomer lacks an intrinsic donor-acceptor structure. However, pronounced orbital perturbation and reorganization occur during its self-assembly, leading to an emergent D-A reconstruction. In contrast, PFC-19 retains orbital distribution similar to its monomer. These distinct behaviors originate from stronger intermolecular interactions in PFC-70, thereby inducing dramatic energy-level reorganization. Consequently, PFC-19 predominantly generates ¹O₂ via an energy-transfer pathway. On the contrary, PFC-70 shows a reduced exciton binding energy and enhanced charge-transfer efficiency, leading to the formation of O₂•^-/•OH via a charge-transfer-dominated process. Accordingly, photocatalytic aerobic organic transformations are achieved, exhibiting excellent efficiency in ¹O₂-mediated C-3 arylation of quinoxalin-2(1H)-ones with PFC-19 and predominant O₂•^--triggered oxidative coupling of benzylamines over PFC-70. This work not only provides a general strategy for regulating intermolecular interactions via molecular engineering but also gains deep insight into exciton regulation for controlling ROS species in noncovalently assembled systems.