Solvatochromism and Solvation Dynamics in CO₂-Expanded Liquids

Abstract

Molecular dynamics (MD) simulations and electronic spectroscopy are used to investigate solvatochromism and solvation dynamics in CH 3 CN+CO 2 mixtures. Experimental results for the probe solute trans-4-(dimethylamino)-4'-cyanostilbene (DCS) reveal a nonlinear dependence of the solvatochromic shifts upon composition, suggesting substantial preferential solvation of DCS by CH 3 CN. MD simulations show that analyzing these shifts using the common assumption of spectral additivity leads to grossly exaggerated estimates of the extent of this preference. Solvation dynamics has been measured using Kerr-gated emission spectroscopy and calculated using MD simulations. Simulation-experiment comparisons offer an interpretation of the observed dynamics in terms of nonspecific preferential solvation.

Controlling Solvation and Mass Transport Properties of Biobased Solvents through CO2 Expansion: A Physicochemical and Molecular Modeling Study

“…In other words, Nile Red will be surrounded according to its affinity for the solvent and CO 2 in a different proportion than the bulk composition. This effect is known as preferential solvation − and has been suggested to be responsible for the nonlinearity of excitation energies (responsible for solvatochromism) in other binary mixtures , and other CO 2 -expanded solvents, as evaluated from physical experiments and simulations. , …”

Modeling Solvation in Supercritical CO2

“…[109][110][111] Following aj oint theoretical-experimentals trategy, Maroncelli and collaboratorsp rovided somep reciousi nsights into the concept of preferentialsolvation in systemscontaining CO 2 -expanded cyclohexane, acetonitrile and methanol. [112][113][114][115] Importantly,t hey performed an analysis showing that simple intermolecular potentials forM Ds imulations can well reproduce awide range of experimental physicochemical properties. Investigating the nature of solute-solvent interactions allowed them to interpret the deviation from linearity of the density dependenceo ft he spectrals hifts of ac hromophore in terms of electrostatic interactions and on the local organization of the (polar) solvent.…”