Exploring Three-Dimensional Porphyrin-Based Covalent Organic Frameworks with Outstanding Solar Energy Conversion

As an emerging class of porous aromatic polymers, porphyrin-based covalent organic frameworks (COFs) have been widely employed in assorted applications due to their unique electronic configurations and properties. Notably, three-dimensional (3D) COFs, characterized by porphyrin cores exposed along steric ordered nanochannels, exhibit great promise for solar energy conversion. However, the development of 3D porphyrin-based COFs continues to present a synthetic challenge, stemming from the scarcity of appropriate topotactic designs and appropriate building blocks. In this study, a series of 3D Por-An-COFs with a reasonable 2-fold lvt-b topology have been synthesized. The 3D architecture enables the periodic alignment of porphyrin units within the conjugated backbones, facilitating light harvesting and interactions between guest species and active centers. Consequently, the 3D Por-An-COF features superior photoresponsive characteristics, including high solar-to-chemical and solar-to-thermal conversion capabilities. In particular, the interfacial water evaporation system based on 3D Por-An-COF achieved an evaporation rate of 1.64 kg m^-2 h^-1, and the related thermoelectric device generates an output voltage of 195 mV. This research not only extends the structural diversity of 3D porphyrin-based COFs for photoenergy conversion but also elucidates the intrinsic dimensionality-dependent photoresponsive behaviors, providing valuable insights for the development of advanced porphyrin-based photosensitizers for a wide range of applications.