Advancing QM/MM Methods to Model Reactions in Ionic Fluids

University Of Miami, Coral Gables FL

Investigators

Abstract

With this award, the Chemical Theory, Models and Computational Methods (CTMC) Program in the Chemistry Division is funding Orlando Acevedo and Jeffrey Overbey of Auburn University to develop and apply theoretical and computational approaches for ionic liquids. The Computational and Data-Enabled Science and Engineering (CDS&E) program in the Division of Advanced Cyberinfrastructure is contributing to the award. With over 100 million pounds of chemical waste treated yearly, a better understanding of how to optimize recyclable solvents for chemical reactions has the potential to impact society from the lab bench top to large-scale industrial manufacturing. Ionic liquids, recyclable solvents composed exclusively of ions, have the ability to accelerate and control a vast range of reactions. However, a new family of ionic fluids called deep eutectic solvents (DES) has recently emerged as an environmentally safer and relatively inexpensive alternative. As a medium for chemical reactions each solvent class has distinct advantages; however, the DES are only beginning to emerge as a potential substitute. The current study will help establish a firm understanding of the intermolecular interactions occurring throughout chemical reactions when solvated by ionic liquids and DES. The strategy is to employ high-end computational modeling to elucidate the effect of these ionic fluids upon the mechanism of product formation for important chemical reactions. Cross-training for students in both the chemical sciences and software development will be provided, preparing them for the STEM workforce. This proposal will also introduce computational chemistry to high school and undergraduate students through a hands-on Instant Supercomputer workshop featuring the construction of a temporary supercomputer. Orland, Overbey and workers investigate chemical reactivity enhancements originating from ionic fluids and to develop new advances in QM/MM methodology. The objective is use QM/MM simulations to resolve controversies regarding the influence of ionic liquids and DES upon rate accelerations, mechanisms, and %ee enhancements when compared to conventional solvents. Development of force field parameters is proposed for multiple choline chloride based DES solvents and 1-alkyl-3-methylimidazolium based ionic liquids. In addition, the creation of a highly parallel, open source software package for performing QM/MM calculations will be made freely available to the scientific simulation community.