Porphyrin-Based Hydrogen-Bonded Organic Frameworks for the Photocatalytic Degradation of 9,10-Diphenylanthracene

Fine tuning of the structures and properties of hydrogen-bonded organic frameworks (HOFs) has been considered to be a huge challenge. Herein, we reported the controlled synthesis of meso-tetrakis(carboxyphenyl)porphyrin (TCPP)-based HOFs via a "counterstrategy" of blocking the strong hydrogen-bonded building units on the TCPP backbones. Mediated by the temperatures, both the kinetically and thermodynamically favored HOF products TCPP-2(DMF), TCPP-4(DMF), and TCPP-6(DMF) can be obtained under 120, 130, and 140 °C, respectively. Results revealed that the numbers and binding positions of end-capped N,N-dimethylformamide (DMF) molecules not only played a key role in the thermal stability and permanent porosity of the present HOFs but also affected significantly the photocatalytic activities for the degradation of 9,10-diphenylanthracene, where a positive correlation between the numbers of DMF molecules and the photocatalytic activities has been established, which can be attributed to variation of the intermolecular van der Waals forces. In addition, upon removal of the lattice water and extra DMF molecules, respectively, HOFs TCPP-2(DMF) and TCPP-6(DMF) can be transformed into a polymorph TCPP-4(DMF)* in the solid state, suggesting a dynamic TCPP-DMF skeleton. This work will promote significantly the development of porphyrin-based HOFs and porphyrin-based photocatalysis materials.