Key words: ibuprofen, supercritical CO2, polymorphism, quantum chemistry, molecular dynamics simulation
The conformational equilibria of ibuprofen in vacuum and in supercritical carbon dioxide are studied using methods of quantum chemistry and classical molecular dynamics. In supercritical carbon dioxide ibuprofen forms 12 different conformations, two of them correspond to the structures of the molecule in the crystal lattice of the first and second polymorph. It is shown that the GAFF force field allows one to obtain the characteristics of conformers, almost coinciding with those obtained by quantum-chemical calculations in the B3LYP/cc-pVTZ level of theory.