Photoredox Catalysis in Aqueous Media by Well-defined Micellar Nanoreactors

尽管许多化学反应物在水中往往表现出较低的溶解度，但自然界可以在水中进行各种化学转化反应。近年来，有机光氧化还原材料的催化作用已成为合成有机化学中一种强有力的新策略，可以进行各种各样的转化。然而，它们在水相中的性能和衬底范围的扩展是一项极其困难的任务。因此，本项目的主要重点是构建能够在可见光照射下促进水中催化的有机光氧化还原活性胶束。特别是在水介质中进行有机反应的能力，以及有效的催化剂回收策略，将是这个项目的目标，代表了可持续和绿色化学的基石。因此，吖啶分子作为有机光氧化还原催化剂的有前途的候选者将被装载到多肽嵌段共聚物胶束的胶束核心中。聚（n -取代甘氨酸）（即多肽）具有生物相容性、可合成性、化学和酶稳定性、化学多样性和结构可控性。确定它们的侧链修饰和选择共聚物中单体的顺序可以直接进行工程设计和确定溶液性质。因此，它们的催化活性胶束体系将被调整并用于芳香化合物的直接C−H氰化，未活化的氟芳烃的亲核取代和烷氧芳烃的酰氨基化。值得注意的是，胶束体系的支架将通过核或壳的共价交联得到加强，从而导致整个体系在抵抗外部刺激和恶劣反应条件（如pH、温度和添加剂）时具有高稳定性。然而，这些方法还将为我们提供其他一些好处，包括调整核心中的相互作用，更好地保护光氧化还原单元免受失活和浸出，催化剂的回收，以及可能改善疏水和亲水区域之间反应物的运输和扩散。该项目还将解决水中有机光氧化还原反应在催化活性、效率和稳定性方面的几个基本障碍。更详细地说，增加光氧化还原反应的寿命，保护活性位点不被分解，减少反应时间，防止光氧化还原催化剂聚集和沉淀。

Despite many chemical reactants often reveal a low aqueous solubility in water, nature could perform all kinds of their chemical transformations reactions in water. Recently, catalysis by organic photoredox materials has emerged as a new and powerful strategy in synthetic organic chemistry to perform a wide variety of transformations. However, performance and extending the substrate scope of them in the aqueous phase is an extremely difficult task. Consequently, the main focus of this project is to construct organophotoredox active micelles that can facilitate catalysis in water under visible light irradiation. Especially the ability to perform organic reactions in aqueous media together with effective recycling strategies for catalysts will be the aim of this project to represent a keystone towards sustainable and green chemistry. Hereby, acridinium molecules as a promising candidate for organophotoredox catalyst will be loaded into the micellar core of polypeptoid block copolymer micelles. Poly(N-substituted glycines) (i.e., polypeptoids) are biocompatible, synthetically accessible, chemically and enzymatically stable, chemically diverse, and structurally controllable. Defined side-chain modification of them and choosing the sequence of the monomers in their copolymers allows the straightforward engineering and determination of the solution properties. Thereby, the catalytic active micellar system of them will be tuned and examined for direct C−H cyanation of aromatic compounds, the nucleophilic substitution of unactivated fluoroarenes, and ipso amination of alkoxyarenes. Noticeably, the scaffold of the micellar system will be reinforced by covalent crosslinking of the core or shell which leads to the high stability of the overall system against external stimuli and harsh reaction conditions such as pH, temperature, and additives. However, these approaches also will provide us several other benefits including adjusting the interaction in the core, better protection of photoredox units from deactivation and leaching, recovery of the catalysts, and presumably improving the transportation and diffusion of the reactants between hydrophobic and hydrophilic domains. The project will also address several fundamental barriers in organic photoredox reactions in the water regarding catalytic activity, efficiency, and stability. In more detail, increasing the lifetime of photoredox reactions, protecting active sites from decomposition, reduces the time of reactions, and preventing the photoredox catalysts from aggregation and precipitation.