Chiral catalysis with hybrid plasmonic nanoparticles

胶体颗粒具有较强的手性效应和较高的催化活性，在手性催化方面具有很大的潜力。然而，它们的关键问题之一是纳米颗粒的结构手性特征与有机基质之间的尺度不匹配。到目前为止，催化剂的结构手性特征的大小——形成所谓的手性体——需要与最终产物的大小相匹配，以赋予手性。本课题旨在建立一种新型分散型杂化等离子体纳米粒子手性催化剂。所提出的催化剂将能够通过通过等离子体场增强转移所需的手性偏置来进行不对称C-C偶联反应，而不是通过匹配结构手性来形成立体体。基于这一机制，不对称催化反应中的正交性可以通过改变简单可逆的触发因素来实现，即交换手性配体或改变激发手性光的手性。此外，通过利用等离子体，避免了对匹配手性体的需要，因此，产生了广泛的具有轴向和立体手性的靶向分子。为此，将设计混合纳米粒子系统，将银纳米粒子的优越等离子体质量与铂族金属的催化活性结合起来。因此，等离子体不仅会赋予底物手性，而且由于设想的核壳粒子设计，等离子体还会通过其强电场增强来促进催化反应。在项目的所有阶段，实验工作将通过电场和手性建模来预测和支持，通过电磁模拟来实现合理的综合方法。

Colloidal particles hold great potential for chiral catalysis due to their strong chiroptical effects and high catalytic activity. However, one of their key problems is the mismatch of scales between structural chiral features of the nanoparticles and the organic substrate. So far, the size of the structural chiral features of the catalyst—forming a so-called chiral bulk—needs to match to the size of the final product in order to to confer the chirality. This proposal aims at establishing a novel chiral catalyst based on hybrid plasmonic nanoparticles in dispersion. The proposed catalyst will be able to perform asymmetric C-C coupling reactions by transferring the required chiral bias via plasmonic field enhancement rather than by matching structural chirality, which is forming a steric bulk. Based on this mechanism, orthogonality in the catalytic asymmetric reaction can be achieved via altering of simple and reversible triggers—namely, the exchange of the chiral ligand or by changing the handedness of the exciting chiral light. Additionally, by exploiting plasmonics, the need of a matching chiral bulk is avoided, hence, giving rise to a broad range of targetable molecules featuring both, axial and stereogenic chirality. For this purpose, the hybrid nanoparticle system will be designed to combine the superior plasmonic quality of silver nanoparticles with the catalytic activity of platinum group metals. Thus, the plasmonics will not only confer the chirality to the substrate, but also boost the catalytic reaction by its strong electric field enhancement due to the envisioned core-shell particle design. During all stages of the project, the experimental work will be predicted and supported by modeling of electric fields and chiral properties via electro¬magnetic simulations aiming for a rational synthetic approach.