Spectroscopic Signatures of Chirality Recognition, Transfer and Amplification: from the Gas Phase to Solution and Interfaces

如果一个分子的镜像不能与自身重叠，那么它就是手性分子，就像我们的左手和右手一样。由于一对镜像的相似性，在许多情况下，用它的镜像替换其中一个镜像，可能会对相关系统的性质产生很少或没有变化。然而，在手性识别事件中，当一个手性分子与另一个手性分子或手性光相互作用时，手性的影响是突出的，就像人类握手的情况一样（即右/右与左/右握手的感觉有多么不同）。更一般地说，手性在生物系统中无处不在，对生命至关重要。手性识别是包括药物在内的许多生物过程的核心，在立体选择化学中具有重要意义。

A molecule is chiral if its mirror image cannot be superimposed onto itself, just like our right and left hands. Because of the similarity of a pair of mirror images, replacing one with its mirror image, may, in many instances, introduce little or no change in the properties of the associated system. In a chirality recognition event when a chiral molecule interacts with another chiral molecule or chiral light, however, the effect of chirality is prominent, just as in the case of a human handshake (i.e. how different a right/right versus a left/right handshake feels). More generally, chirality is ubiquitous in biological systems and essential for life. Chirality recognition is at the heart of many biological processes including those involving pharmaceuticals and is of chief importance in stereoselective chemistry. We aim to understand the effects of solvent and light radiation on chirality recognition and transfer events at the molecular level in order to formulate rigorous chirality recognition and transfer models with predictive power and to develop new strategies to control these events with light. We will pursue innovative research activities in four core directions which are unified under the central theme of chirality and chirality recognition in the next funding cycle: 1) In order to follow the first few crucial steps of aggregation and solvation in unprecedented detail, we will apply chirped-pulse microwave spectroscopy to study clusters of chiral molecules and solvent molecules with increasing number of subunits. Such larger clusters have rarely been investigated before. 2) We will utilize two powerful chiroptical tools, namely vibrational circular dichroism and Raman optical activity spectroscopy to probe non-covalent interactions and chirality transfer in solution. We will focus on mechanisms of chirality transfer/amplification under (near) resonance which have hardly been explored before. 3) Building on our prior success in instrument development, we will further develop our hybrid mass-laser spectroscopic instrument by coupling it to a helium nanodroplet isolation spectrometer. The hybrid laser-mass instruments will allow us not only to probe chirality recognition in aggregates of amino acids and peptides at room temperature and at 0.4 K, but also to access reaction intermediates by utilizing the gentle helium matrix to stabilize them. 4) We will explore chirality recognition and induction at liquid-liquid interfaces, a new research direction we initiated. The outcome of the proposed research will be valuable to many subfields in chemistry, physics, and biology where chirality plays a significant role. The fundamental knowledge gained will be important for developing a broad range of chiral technologies from sensors for pharmaceutical processes and environmental monitoring to novel catalysts for chiral drug syntheses.