Solution and solid state studies of hydrogen bonding in substituted oxazolidinones by spectroscopic and quantum chemical methods

Structure and hydrogen bonding interactions of bioactive oxazolidinones have been studied by means of NMR and vibrational spectroscopies and quantum chemical calculations. We have demonstrated that oxazolidinone derivatives form hydrogen bonds in solution and solid state. Conformational space search has revealed predominant conformations in solution. In low polarity solvents, such as chloroform, dimers are formed presumably by intermolecular hydrogen bonds between two oxazolidinone molecules forming the most stable complexes, which has also been found in the solid state by IR spectroscopy and crystallography. In solvents of higher polarities, like methanol and dimethylsulfoxide, intermolecular interactions with solvent molecules and in dimers are present. As expected, raising the temperature broke hydrogen bonds, which was reflected in down-field chemical shifts of corresponding resonances. On the other hand, raising the solution concentration considerably affected oxazolidinone resonances only in chloroform, corroborating the formation of oxazolidinone dimers. These results may help in better understanding oxazolidinone structure, properties and interactions when designing new bioactive compounds and pharmaceutical products.