(451c) Tuning Deep Eutectic Solvent Properties with Phenolic-Derivative Hydrogen Bond Donors

Deep Eutectic Solvents (DESs) are an emergent class of liquids with a host of useful properties such as low volatility and a wide chemical design space. This has resulted in numerous applications such as redox flow batteries, biosynthesis, metals processing, separations, and catalysis. Despite these successful applications, little is known about how the fundamental molecular-level interactions in DESs result in their useful bulk properties. Type III DESs, composed of a hydrogen bond donor (HBD) and hydrogen bond acceptor (HBA) pair, are the most frequently studied with many studies investigating “hallmark” DESs Reline, Ethaline, and Glyceline. By investigating these DESs experimentally and computationally, it has been seen that HBD–ion interactions vary significantly from mixture to mixture hinting that small changes in HBD molecular structure strongly influences bulk liquid properties. The current study uses molecular dynamics simulations to investigate phenolic-derivative HBD mixtures with choline chloride, a common HBA, using the benzene ring structure as a scaffold to make molecular structure changes and analyze the resultant changes in density, viscosity, self-diffusion coefficients, and many other properties of interest. The mixtures studied were 3:1 mixtures of HBD:choline chloride, with a total of four HBDs: phenol, catechol (ortho-hydroxyphenol), ortho-chlorophenol, and ortho-cresol (ortho-methylphenol). Simulations captured density and viscosity behaviors of these mixtures extremely accurately. Further unique dynamical and structural features were also discovered when comparing mixtures, emphasizing and quantifying how DES properties are highly influenced by fine changes in HBD structure.