基于上转换荧光共振能量转移的超分子手性光敏化

该项研究致力于解决不对称光敏化反应中存在的光学产率低且适用于现有敏化方法的手性光化学反应类型少的缺点，计划构建一个高立体选择性的并且适用范围广的新型手性光敏化策略。该研究将制备上转换发光纳微米颗粒用作光敏剂，利用红外激光为激发光源以避免对光反应底物的直接激发，进而实现基于荧光共振能量转移机理的手性光敏化。手性主体分子将被修饰到具有上转换发光特性的纳微米颗粒的表面，借助主体分子对光反应底物的包接作用将底物分子拉近到光敏剂的表面，以实现高效能量转移和手性传递。该研究拟通过调整不同的影响因素，包括主体分子结构、上转换发光纳微米颗粒的尺寸和掺杂特性、溶剂、温度以及激发波长等条件获得优化的光敏化效率和立体选择性。另外，这一敏化策略将被应用于考察几个不同的手性光化学反应来评价其普遍适用性。该研究的实施有望构建一类光稳定性高、适用性广、立体选择性高且易于回收再利用的新型手性光催化剂。

The goal of this research is to solve the current limitations of chiral photosensitizations, namely low optical yields and limited reaction scope, and thus establish a new and widely applicable strategy to realize highly stereoselective catalytic chiral photoreactions. In this project, chiral photosensitization based on fluorescence resonance energy transfer will be applied by using upconverting nano/micro-particles as photosensitizers. Photolysis will be carried out with infrared lasers to avoid direct excitation of photosubstrates. Chiral host molecules will be grafted onto the surface of upconverting nano/micro-particles to ensure highly efficient transfer of chirality and energy by virtue of complexation of the photosubstrate with the host molecules close to the surface of upconverting nano/micro-particles. We intend to improve energy transfer efficiency and stereoselectivity of chiral photoreactions by optimizing influencing factors, including the chemical structure of chiral hosts, the size and doping characters of upconverting nano/micro-particles, the reaction solvent and temperature, and irradiation wavelengths. This new chiral photosensitization strategy will be applied to different chiral photoreactions in order to evaluate the general applicability. The implementation of this project will establish a new family of chiral photocatalysts that stand out due to their high photostablity, wide applicability, good stereoselectivity, and, importantly, facile recyclability and reusability.