High-pressure NMR spectroscopy in studies of the conformational composition of small molecules in supercritical carbon dioxide

An experimental approach in conducting NMR measurements at supercritical parameters of state is discussed. A novel design of the high-pressure NMR cell was developed which allowed eliminating the field inhomogeneity and, thus, increasing the sensitivity of the experiment at the supercritical state. Analysis of the MD simulations and NMR data showed that two conformers of ibuprofen dominate in the solution in supercritical CO2 along the critical isochore 1.3 rho cr(CO2). Conformer populations calculated from MD simulations and from NMR spectra agree with each other. (C) 2020 Elsevier B.V. All rights reserved.