Treatment and importance of conformations in COSMO-RS


Andreas Klamt,, COSMOlogic GmbH&CoKG, Burscheider Str. 515, Leverkusen, 51381, Germany and Michael Diedenhofen,, COSMOlogic GmbH & Co.KG, Burscheider Str. 515, Leverkusen, D-51381, Germany.
COSMO-RS is a novel predictive method for thermodynamic properties of fluids. COSMO-RS calculates the thermodynamic data from molecular surface polarities resulting from quantum chemical calculations of the individual compounds. The molecular interactions, i.e. electrostatics, hydrogen bonding and dispersion, are represented as functions of surface polarities. Using an efficient thermodynamic algorithm COSMO-RS converts the molecular polarity information into thermodynamic data of fluids, i.e. vapor pressures, activity coefficients, excess properties, etc.

Originally, COSMO-RS considered only one conformation per compound, but since 2001 the COSMOtherm implementation of COSMO-RS enables a thermodynamically consistent treatment of multiple conformations in COSMO-RS simulations. This is of importance, because some molecules may occupy considerably different conformations in polar and non-polar solvents, respectively. In this talk we will report on our experience regarding the importance of conformational treatment, demonstrate some example cases, and discuss a strategy how to find the relevant conformations of molecules in polar and non-polar solvents.


Computational Phase Equilibria
8:00 AM-11:50 AM, Tuesday, April 8, 2008 Morial Convention Center -- Rm. 337, Oral

Division of Computers in Chemistry

The 235th ACS National Meeting, New Orleans, LA, April 6-10, 2008