Solvation and solvatochromism in CO2-expanded liquids

I&EC 80

Hongping Li1, Sergei Arzhantzev2, Chet Swalina, chet@chem.psu.edu2, and Mark Maroncelli2. (1) Department of Chemistry, Zhengzhou University, No. 100 Science Road, Zhengzhou, Henan 450001, China, (2) Department of Chemistry, The Pennsylvania State University, 104 Chemistry Building, University Park, PA 16802
A combination of electronic spectroscopy and molecular dynamics (MD) simulations are used to investigate the equilibrium properties as well as dynamical aspects of solvation in a set of gas-expanded liquids (GXLs) including cyclohexane + CO2, acetonitrile + CO2, and methanol + CO2. Electronic absorption and emission spectroscopy using the probe solutes 10-bis(phenylethynyl)anthracene (PEA) and coumarin 153 (C153) reveal a non-linear dependence of spectral frequencies on the composition of these mixtures suggesting substantial preferential solvation of both solutes. Corresponding computer simulations show that the commonly used assumption of a linear relation between spectral shifts and local compositions grossly exaggerates the extent of preferential solvation in these mixtures. The dependence of solvation dynamics on GXL composition for the solute trans-4-(dimethylamino)-4'-cyanostilbene (DCS) has been measured using Kerr-gated emission spectroscopy and also computed using MD simulations. Simulation-experiment comparisons offer an interpretation of the observed dynamics.
 

Green Chemistry and Engineering with Gas Expanded Liquids and Near-Critical Media
8:00 AM-11:25 AM, Wednesday, August 22, 2007 Boston Park Plaza -- Clarendon Rm, Oral

Division of Industrial & Engineering Chemistry

The 234th ACS National Meeting, Boston, MA, August 19-23, 2007