Structure and Ultrafast Dynamics in Deep Eutectic Solvents

ended

Deep eutectic solvents (DESs) are binary-component mixtures which melt at a temperature that is several tens to a few hundreds of degrees lower than an ideal binary mixture of the same two compounds in the same ratio. DESs are usually environment-friendly solvents that hold great promise for replacing harmful ionic liquids and volatile organic compounds in chemical and industrial applications. Despite this significant potential, experimental investigations of the fundamental molecular-scale properties and dynamics of these solvents are strikingly lacking. This proposal (acronym STUDYES) aims to identify the underpinning molecular structures and ultrafast dynamics of DESs for the first time. Within STUDYES, I will use state-of-the-art ultrafast, non-linear spectroscopic techniques to unravel the real-time structural and dynamical behaviour of these solvents through their molecular vibrations. I will characterize the ultrafast structural dynamics at the eutectic point of DESs through both temperature- and composition-dependent nonlinear vibrational spectroscopic measurements. The stretching vibrations of the nascent functional groups will be probed in one- and two-dimensional experiments, which will allow a direct visualization of the structural heterogeneities, intermolecular interactions and inter-mode couplings in DESs. I will also investigate the effects of an external agent such as water on the structure and ultrafast dynamics of the DES and identify the critical concentration at which water disrupts the DES structural order. The results of these experiments will provide an important first step to a molecular-level understanding of the special macroscopic physicochemical properties of DESs.