Correlation-Based\nPredictions of Gas Solute Diffusivity\nin Ionic Liquid Solvents Based on Solvent-Accessible Surface Area

In our prior study [Olowookere, F. V.; Turner, C. H. J. Phys. Chem. B 2023, 127(42), 9144–9154], we introduced a new scaling relationship\nto predict gas solute diffusion at challenging conditions, focusing\non CO<sub>2</sub> and SO<sub>2</sub> diffusion in multivalent ionic\nliquid (IL) solvents. This work extends our initial exploratory study\ninto a much broader array of systems, encompassing additional solutes\n(N<sub>2</sub>, CH<sub>4</sub>, C<sub>2</sub>H<sub>6</sub>, C<sub>3</sub>H<sub>8</sub>, C<sub>3</sub>H<sub>8</sub>O, and H<sub>2</sub>O) and a variety of different ionic liquid species ([Bzmim<sub>3</sub>]<sup>3+</sup>, [Bzmim<sub>4</sub>]<sup>4+</sup>, [BMIM]<sup>+</sup>, [EMIM]<sup>+</sup>, [HMIM]<sup>+</sup>, [NapO<sub>2</sub>]<sup>2–</sup>, [BzO<sub>3</sub>]<sup>3–</sup>, [BF<sub>4</sub>]<sup>−</sup>, [Tf<sub>2</sub>N]<sup>−</sup>, and [PF<sub>6</sub>]<sup>−</sup>). Our study demonstrates a remarkably\nrobust logarithmic correlation between solute diffusion and solvent\naccessible surface area (SA) across 20 different additional systems.\nWe perform comprehensive analyses of the underlying molecular phenomena\nresponsible for this correlation, including solute lifetime distributions,\nvoid space dynamics, and Voronoi tessellation, in order to elucidate\na stronger mechanistic understanding of this behavior. Our findings\nhighlight a direct link between the solvent accessible SA and the\nsize of the void domains. Overall, our scaling approach provides an\nefficient and reliable approach for predicting diffusion from analyses\nof short simulations at higher temperatures.