Design,Synthesis,Characterization And Application Of Photocatalytic Covalent Organic Frameworks

Currently, along with the depletion of fossil fuels, the discovery and utilization of novel renewable energy is becoming more and more important. Converting solar energy into chemical energy is a new efficient approach that scientists are considering about. As a new type of crystalline porous materials, covalent organic frameworks (COFs) are a new candidate as the photocatalyst in these procedures. COFs possess extended π-conjugation framework, regular pore structure and high surface area, all of which are essential for enhancing the photocatalytic activity. Moreover, the stability of COFs materials makes further applications feasible. Consequently, the optical and electronic applications of COFs have aroused increasing interest of scientists, especially in the potential application as photocatalysts. However, the photocatalytic applications of COFs materials as a metal-free photocatalyst have not yet been reported.This thesis mainly focuses on the design, synthesis and characterization of photoactive COFs. Then we further study the influence factors between the photoelectric properties and the photocatalytic applications. Accordingly, the research work of this thesis can be divided into two parts:(1) A nitrogen-rich hydrazine-based COF, COF-LZU5was successfully synthesized via the "bottom-up" strategy. COF-LZU5has a high BET surface area (1473m2/g) and a regular pore (pore size:2.0nm). Furthermore, the ability of light harvesting makes COF-LZU5could be further applied as a metal-free photocatalyst in the cross dehydrogenative coupling reaction of2-aryl-1,2,3,4-tetrahydroisoquinolines and nucleophiles. Additionally, the material could be reused.(2) Based on the photocatalysis of COF-LZU5, we further explored the structure-property relationship of COFs and the factors of photocatalytic activity, hoping to obtain more guidance in the design and synthesis of photocatalytic COFs. Under this topic, we synthesized five imine-linked COFs with different electric effect groups. The structures were primarily characterized and their structure-property relationship was then investigated.