光功能共价有机骨架材料的合成及其光催化C-H功能化研究

Covalent organic frameworks (COFs) as an emerging class of porous crystalline polymers are covalently assembled from organic building blocks. The well-defined COF materials with periodic architectures and tailored functionalities offer superior potential for a variety of applications, such as gas storage and seperation, optoelectricity, energy storage, proton conduction, drug delivery, and catalysis. We have recently demonstrated that hydrazone-based COFs provide a promising platform for highly efficient and reusable photocatalysts in cross-dehydrogenative coupling (CDC) reactions. It is challenging to develop photofunctional COFs by bottom-up or post-synthesis strategies to achieve light harvesting and further highlight the application of COFs in photocatalysis with high efficiency, low cost, and minimum environmental impact and energy consumption. In this project, we will design and synthesize hydrazide and aldehyde building blocks with different electronic factors to construct new hydrazone-based COFs by reversible polycondensation reaction, and further study their photocatalytic properties in C-H functionalization reaction of tetrahydroisoquinolines (THIQs). The influence of different COFs catalysts, the amount of catalysts, solvents, visible-light source on the photocatalytic performance in these organic transformations will also be explored. The highly active COFs will further be applied as photocatalysts in C-H functionalization asymmetric reaction of THIQs by employing chiral induced synergistic catalytic strategies. And the recyclability and reusability of COFs catalysts will be examined in the heterogeneous catalytic systems for practical application. To gain structural insights into the reused catalyst, we will characterize COFs catalysts after recycling test using various analytical methods. Moreover, the structure-property relationship of COFs and the factors of photocatalytic performance will be summarized. Thus, this work will provide both theoretical and practical contributions to developing COFs photocatalysts.

共价有机框架(COFs)是一类共价键连接的、结构有序的、功能可控的结晶多孔聚合物材料，在很多领域具有非常好的潜在应用。我们近期报道了酰腙键构筑的COFs催化剂，在交叉脱氢偶联（CDC）反应中展示了优异的光催化活性。在多孔材料非均相催化领域里，一项富有挑战性的工作是开发高效率、高选择性、低成本的COFs光催化剂。基于我们在COFs光催化领域的前期研究，本项目拟合成系列酰腙键构筑的新型COFs材料，并研究其催化四氢异喹啉C-H官能化反应的光催化性能。探究反应中COFs催化剂、催化剂用量以及反应溶剂等参数对光催化性能的影响。在优化的催化体系中，利用手性诱导协同催化策略，向体系中添加手性助催化试剂，致力于光催化的C-H官能化不对称合成反应。我们总结出该类材料的构效关系以及影响COFs材料光催化能力的因素。期望通过此项研究工作的开展，为COFs光催化剂的设计合成及应用提供新思路。

共价有机骨架（COFs）是一类新兴的结晶多孔材料，在气体储存与分离、光电、储能、催化等领域有着广泛的应用前景。到目前为止，有限的有机可逆反应被应用于构筑大量的二维COFs和少数三维COFs。在大多数COFs中，连接单元通常是硼酸酯、三嗪环、亚胺或酰腙等。由于COFs具有周期性的结构、功能可控及层层堆叠的特征，COFs被认为是光生电子/空穴对有效分离和迁移的理想平台，从而为多相光催化剂的设计提供了新的机遇。. 本项目成功合成了系列酰腙键构筑的新型COFs材料。所合成的COFs具有优异的比表面积、结晶度以及优良的热稳定性和化学稳定性。在可见光照射下，研究了COFs催化四氢异喹啉C-H官能化反应的光催化性能。研究了反应中COFs催化剂、催化剂用量以及反应溶剂等参数对光催化性能的影响。实验结果表明，光催化剂、光源和氧气对有效的脱氢偶联反应是必不可少的。通过自下而上或后合成的策略来开发光功能COFs，并实现有效光捕获，进一步发展COFs材料在光催化中的更广泛应用，仍然是一个具有挑战性的课题。为提高COFs的光催化性能，采用分子工程策略合成了不同能带隙的光活性材料[HC≡C]x-TFB-COFs。[HC≡C]x-TFB-COFs具有较大的比表面积、优异的稳定性、良好的光捕获能力和合适的能带。[HC≡C]x-TFB-COFs在芳基硼酸氧化羟基化反应中也表现出优异的催化效率及重复利用性能。此外，通过孔表面功能化策略构建了高亲水性COF材料（TFPT-BMTH）。该COF材料进一步作为多相光催化剂用于水相苄胺氧化偶联反应。所合成的COF材料对于水中苄胺的光催化氧化具有显著的催化活性、底物适用性和可循环利用性。另外，课题组也拓展了COFs光催化体系的应用范围，也实现了COFs光催化自由基加成环化反应。.　　通过该项目的开展，我们深入研究了光催化剂结构与功能关系，总结出了该类材料光催化构效关系以及COFs材料光催化的影响因素，为COFs光催化剂的设计合成及应用奠定了实验及理论基础。