Enhancing the Iodine Adsorption Capacity of Pyrene-Based Covalent Organic Frameworks by Regulating the Pore...

Regulating of pore environment is an efficient way to improve the performance of covalent organic frameworks (COFs) for specific application requirements. Herein, the design and synthesis of two pyrene-based 2D COFs with -H or -Me substituents, TFFPy-PPD-COF and TFFPy-TMPD-COF are reported. Both of them show long order structure and high porosity, in which TFFPy-PPD-COF displays a larger pore volume and bigger BET surface area (2587 m² g^-1 , 1.17 cm³ g^-1 ). Interestingly, TFPPy-TMPD-COF exhibits a much higher vapor iodine capacity (4.8 g g^-1 ) than TFPPy-PPD-COF (2.9 g g^-1 ), in contrast to their pore volume size. By using multiple techniques, the better performance of TFPPy-TMPD-COF in iodine capture is ascribed to the altered pore environment by introducing methyl groups, which contributes to the formation of polyiodide anions and enhances the interactions between the frameworks and iodine. These results will be helpful for understanding the effect of pore environment in COFs for iodine uptake and constructing novel structure with high iodine capture performance.