One-step synthesis of a highly crystalline covalent organic framework with olefin and imine dual linkages for tuning the catalytic activity

Abstract

Although the variety of covalent organic frameworks (COFs) is expanding, it is still limited and challenging to construct COFs through the formation of two types of covalent linkages. In this study, we present a one-step method for the preparation of a highly crystalline COF with olefin and imine dual linkages, which is achieved by organobase-catalyzed orthogonal Schiff base reaction and Knoevenagel condensation. Intriguingly, this method can also be utilized for the synthesis of an imine-linked COF. The resulting TFPT-APA COF with dual linkages possesses a high specific surface area of 1329 m² g⁻¹ and exhibits enhanced performance in photocatalytic degradation of pollutants over the structurally similar imine-linked TFPT-PA COF. Further studies reveal that TFPT-APA can generate singlet oxygen (¹O₂) under light irradiation, whereas TFPT-PA does not possess this capability. This study not only provides a new approach for the design and synthesis of COFs with dual linkages, but also opens up possibilities for constructing COFs with diverse catalytic properties.