(585d) Understanding Electronic Properties of 1-n-Alkyl-3-Methylimidazolium Chloride Ionic Liquids with Iron Porphyrin

Ionic liquids have garnered considerable attentions as potential replacements for volatile organic solvents in industrial applications due to their unique properties such as low vapor pressure, low flammability, and design flexibility. However, they cannot be assumed to be environmentally friendly, as many ionic liquids have been shown to be toxic to microorganisms. It has also been demonstrated that several ionic liquids are recalcitrant to biodegradation. However some ionic liquids do exhibit favorable biodegradable characteristics. Cytochrome P450 bearing iron porphyrin in their catalytic pocket has been proposed as a potential enzyme in the ionic liquid biodegradation. However, it is not clear how ionic liquids interact with FeP in the binding pocket. In this presentation, we investigate the interaction of ionic liquids 1-n-alkyl-3-methylimidazolium [C_nmim]⁺Cl (n = 2, 4, 6, 8, and 10) with FeP using electronic structure calculations. As these systems are characterized by a large number of degree of freedom, we will demonstrate how a thorough exploration of the available conformational space is required to search for an energy minimum. We will characterize the final optimized geometry with a coordinate system that is affixed to FeP so that the structures across the homologous series can be compared. Results of electronic properties such as the highest occupied molecular orbital energy and the lowest occupied molecular orbital energy will be presented. We will also calculate the reduction potential of the optimized structures as it represents the second step in the overall catalytic cycle that leads to the biodegradation of imidazolium-based ionic liquids.