EDOT-Decorated Covalent Organic Polymers as Versatile Metal-Free Photocatalysts for Organic Transformations

Abstract

Covalent organic polymers (COPs) with conjugated systems and chromophores are often used as super-organic dyes and have potential in photocatalysis. It is necessary to exploit heterogeneous metal-free photocatalysts with wide applicability and high efficiency. 3,4-Ethylenedioxythiophene (EDOT) here was designed as the photoactive unit and constructed into the EDOT-conjugated microporous polymer (EDOT-CMP) and EDOT-covalent triazine framework (EDOT-CTF). The photoelectric properties of the two synthetic EDOT-COPs were thus enhanced. Of note is that EDOT-triazine endowed the EDOT-CTF with an obvious donor–acceptor structure and thus generated favorable exciton dissociation efficiency. EDOT-COPs proved to be versatile photocatalysts for photoredox reactions. At least eight conversions, e.g., oxidative coupling of benzylamines (85- > 99% yield) and construction of C–S bonds in olefines (80–96% yield) and indoles (88–99% yield), could be promoted smoothly by EDOT-COPs and especially EDOT-CTFs. EDOT-COPs also showed high photoactivities for the degradation of rhodamine B. The research about EDOT-COPs here contributes references for the design and synthesis of widely applicable COP photocatalysts.