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

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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.