A Selenium Atom Involved Covalent Organic Framework for Window Ledge Photocatalytic Oxidation of Sulfides

Abstract

Covalent organic frameworks (COFs) driven photocatalytic organic transformations especially photooxidation reactions have become a fertile topic and attracted numerous research attentions. Boosting the charge generation and transport process is the key factor for achieving high catalytic efficiencies. As one of the most effective strategies, the introduction of “heavy atoms” into the long-range ordered conjugated backbones can effectively facilitate the intersystem crossing (ISC) process and hence improve the generation of active oxygens, which is beneficial for the oxidation. In this work, we designed and synthesized a benzoselenadiazole based covalent organic framework (COF) material,   BSe-COF with heavy atom of selenium (Se), and a benzothiadiazole based  BT-COF with isomorphic backbone for comparison. Compared to  BT-COF,   BSe-COF exhibits broader absorption range, stronger photocurrent response and enhanced intersystem crossing (ISC) with higher singlet oxygen ( ¹O ₂) generation efficiency. When applied in photocatalytic organic transformation,   BSe-COF presents remarkably higher photocatalytic activity in the oxidation of sulfides than  BT-COF under the irradiation of blue LED lamp. Furthermore,   BSe-COF can be used as efficient photocatalyst for the window ledge reaction with high yields (over 84%) of various sulfoxides from a wide range of thioether substrates scope.

Keywords

Covalent organic framework / Benzoselenadiazole / Density functional theory / Heavy atom / Photocatalysis / Photooxidation / Singlet oxygen / Window ledge reaction

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