Rotational Spectroscopy And Conformational Space Of Glycerol Dimers

Glycerol (CH2OHCHOHCH2OH) is a colorless, odorless, and viscous liquid with a sweet taste and is widely used in food and drug industry. This polyol compound with three hydroxyl groups is capable of taking on many different intra- and intermolecular hydrogen bonding topologies, leading to highly complex conformational spaces for its monomer and dimer. Rotational spectra of five of its monomeric conformers had been reported before.[1],[2] In the current study, we apply CREST, a conformer-rotamer ensemble sampling tool developed by the Grimme group,[3] together with DFT calculations to systematically explore the conformational spaces of its monomer and dimer. Rotational spectra of glycerol in the 1-12 GHz range were recorded using a chirped-pulse Fourier transform microwave spectrometer and analyzed. Rotational transitions of several conformers of the binary glycerol complex were assigned. The structure-energy relationships of the conformers of the glycerol dimer and the corresponding monomer will be discussed. [1] V.V. Ilyushin, R.A. Motiyenko, F.J. Lovas, and D.F. Plusquellic, J. Mol. Spectrosc. 2018, 251,129. [2] G. Maccaferri, W. Caminati and P.G. Favero, J. Chem. Spc., Faraday Trans., 1997, 93(23), 4115. [3] S. Grimme, J. Chem. Theory Comput. 2019, 15, 2847