Conformational changes in hydroxyl functional group upon hydration: the case study of Endo Fenchol

The hydration of endo-fenchol has been studied in the gas phase using a combination of Fourier transform microwave spectrometer coupled to a supersonic jet expansion and theoretical calculations in the 2 to 20 GHz range. An endo-fenchol∙∙∙Water complex was observed. Multi-isotopic substitutions of deuterated species have been also studied in order to confirm the identity of the observed monohydrated fenchol due to the flexibility of the OH group. Herein, the structure of the observed conformer was unveiled. Water induced an alteration in the arrangement of the hydroxyl group. The observed species is stabilized by a hydrogen bond between one water molecule and the highest energy conformer of endo-fenchol, which was not observed in our previous study of fenchol monomer.. This study highlights the flexibility of alcohol molecules and the effect of the strong (O-H∙∙∙O) and weak (C-H∙∙∙O) hydrogen bonds in the stabilization of the cluster with water.