Solvation in Supercritical Fluids

ANA C. FURLAN, FRANK W. FÁVERO, JAVIER RODRIGUEZ, DANIEL LARIA, AND MUNIR S. SKAF

Solvation Effects on Molecules and Biomolecules Computational Methods and Applications.

Springer

Año: 2008; p. 433 - 454

In this chapter, we will review some of the work that we have been doing in recentyears in the context of solvation and dynamical properties in polar and non-polar supercriticalsolutions using molecular dynamics computer simulations. First we willdiscuss solvation of alkaloids in SC-CO2 and provide detailed molecular views of themain structural features of the local density augmentation around simple alkaloidsand solute translational and reorientational dynamics under different pressure andtemperature conditions [24], and also describe the effects of the presence of smallfractions of ethanol as co-solvent on solvation structures and dynamics [25]. In thesecond half of this chapter, we will focus on properties of polar fluids such as waterand ammonia under supercritical conditions. We will start with the dielectric behaviorof supercritical water (SCW) [26] and review comparisons between simulationsand experimental data, some of which remain controversial to this date. Next, we willconcentrate on solvation dynamics in SCW using a model chromophore that capturesthe essential elements of a photo-excitable dye typically used in time-resolved Stokesshift fluorescence experiments, and conclude by reviewing equilibrium structuraland dynamical aspects of excess electrons solvated in supercritical water [27] andsupercritical ammonia [28] as function of solvent density and comparisons with experimentallymeasured optical absorption spectra of these systems.