Construction of Fully Conjugated Covalent Organic Frameworks via Facile Linkage Conversion for Efficient Photoenzymatic Catalysis

Abstract

Covalent organic frameworks (COFs) with improved stability and extended π-conjugation structure are highly desirable. Here, two imine-linked COFs were converted into ultrastable and π-conjugated fused-aromatic thieno[3,2-<i>c</i>]pyridine-linked COFs (<b>B-COF-2</b> and <b>T-COF-2</b>). The successful conversion was confirmed by infrared and solid-state ¹³C NMR spectroscopies. Furthermore, the structures of thieno[3,2-<i>c</i>]pyridine-linked COFs were evaluated by TEM and PXRD. It is noted that a slight difference in the structure leads to totally different photoactivity. The fully π-conjugated <b>T-COF-2</b> containing triazine as the core exhibited an excellent photocatalytic NADH regeneration yield of 74% in 10 min.