Molecular Dynamics Simulations of Solvation and Solvent Reorganization Dynamics in CO2-Expanded Methanol and Acetone

John L Gohres; Alexander V Popov; Rigoberto Hernandez; Charles L Liotta; Charles A Eckert

doi:10.1021/ct800353s

Molecular Dynamics Simulations of Solvation and Solvent Reorganization Dynamics in CO2-Expanded Methanol and Acetone

J Chem Theory Comput. 2009 Feb 10;5(2):267-75. doi: 10.1021/ct800353s.

Authors

John L Gohres¹, Alexander V Popov¹, Rigoberto Hernandez¹, Charles L Liotta¹, Charles A Eckert¹

Affiliation

¹ School of Chemical & Biomolecular Engineering, School of Chemistry & Biochemistry, Specialty Separations Center, and Center for Computational and Molecular Science and Technology, Georgia Institute of Technology, Atlanta, Georgia 30332-0100.

PMID: 26610103
DOI: 10.1021/ct800353s

Abstract

Composition-dependent solvation dynamics around the probe coumarin 153 (C153) have been explored in CO2-expanded methanol and acetone with molecular dynamics (MD) simulations. Solvent response functions are biexponential with two distinct decay time scales: a rapid initial decay (∼0.1 ps) and a long relaxation process. Solvation times in both expanded solvent classes are nearly constant at partition compositions up to 80% CO2. The extent of solvation beyond this composition has the greatest tunability and sensitivity to bulk solvent composition. Solvent rotational correlation functions (RCFs) have also been used to explore rotational relaxation. Rotations have a larger range of time scales and are dependent on a number of factors including bulk composition, solvent-solvent interactions, particularly hydrogen bonding, and proximity to C153. The establishment of the solvation structure around a solute in a GXL is clearly a complex process. With respect to the local solvent domain around C153, it was seen to be primarily affected by a nonlinear combination of the rotational and diffusive transport dynamics.