Chiral aqueous-phase chemistry

ongoing

Most chemical reactions in lifeforms take place in aqueous environments and probing biochemical molecules and their reactions in the aqueous phase is indispensable for advancing fundamental and applied science. Equally, intermolecular effects involving chiral complexes are highly relevant to life sciences, where hydration and chiral recognition are fundamental biochemical processes, typically occurring at aqueous interfaces. All of these processes are driven by electronic structure interactions with water molecules and are intimately connected with aqueous-phase electron binding energies. The prime experimental tool to access these properties is photoelectron spectroscopy (PES). With the recent invention of liquid-microjet-(LJ) PES, compatible with highly volatile liquid water and aqueous solutions, this technique has significantly contributed to modern water research, providing important insights into formerly elusive water properties, such as absolute energetics and solute interfacial distributions. I propose to explore chirality in aqueous solution using a novel aspect of photoelectron emission: photoelectron circular dichroism (PECD). It is site-specific and sensitive to chemical environment and structure. Furthermore, PECD exceeds absorption-based chiroptical signals by orders of magnitude, allowing application to dilute samples, potentially including interfacial layers, akin to PES. PECD has been demonstrated for isolated chiral molecules and clusters, and measurement of PECD effects in aqueous solution would mark a scientific breakthrough. The aim of AQUACHIRAL is to combine LJ-PES with PECD to (1) probe aqueous-phase chirality using enantioselective electronic-structure fingerprints of solutes and to (2) follow the stereochemistry of prominent chemical reactions in aqueous solution, e.g. slow glucose mutarotation. To achieve this, experimental technology must be extended, with novel liquid jets and electron detection systems being developed and optimized.