Solvation structure and molecular interactions of ibuprofen with ethanol and water: A theoretical study

Molecular dynamics (MD) simulations were applied to systematically investigate the interactions and solvation structures of ibuprofen with ethanol or water at the temperature ranging from 298.15 K to 333.15 K. The results demonstrated that ibuprofen molecules mainly acted as HB donors in ethanol while in water as both HB donors and HB acceptors by establishing two HBs in a sequential closed cycle with water molecules. It was evident that the strength of hydrogen bonds (HBs) attenuated gradually in following orders: ibuprofen-ethanol > ethanol-ethanol > ibuprofen-ibuprofen (in ibuprofen-ethanol mixtures), ibuprofen-ibuprofen > ibuprofen-water > water-water (in ibuprofen-water mixtures). HBs weakened with increasing temperature, while the HB structure kept almost unchanged. A great amount of HBs in water molecules hindered the introduction of ibuprofen. Additionally, the electrostatic and van der Waals interactions, as well as the solvation structures of ibuprofen with both ethanol and water were nearly unaffected by temperature. (C) 2020 Elsevier B.V. All rights reserved.