Issue 39, 2016

Subtle solvation behaviour of a biofuel additive: the methanol complex with 2,5-dimethylfuran

Abstract

Methanol is shown to engage two nearly equivalent solvation sites in 2,5-dimethylfuran, the electron-rich π cloud and the electron-deficient oxygen site. The latter only wins by a slight margin, thanks to the methyl group undergoing secondary interactions with the ring. These secondary attractions reduce the hydrogen bond-induced OH frequency shift of the OH–O contact, whereas the π cloud allows for a combined action of both binding mechanisms in the OH–π arrangement. In total, the hydrophobic character of 2,5-dimethylfuran is well reflected in the weak pair interactions, as judged by the small solvation shifts. Methanol solvation of 2,3-benzofuran is revisited and shown to be more ambiguous than previously thought, involving competition between five- and six-ring π clouds and the oxygen site for the OH group. The six-ring π cloud is slightly preferred. FTIR spectroscopy in supersonic jets is in systematic agreement with dispersion-corrected harmonic B3LYP and also B2PLYP predictions for these competing furan docking sites. Deuteration of the OH group helps to identify the docking sites because of its attenuated zero-point energy weakening effect on localized hydrogen bonds. Extension to less methylated furans is proposed in the context of a future forecasting competition for the performance of quantum chemical methods for intermolecular interactions.

Graphical abstract: Subtle solvation behaviour of a biofuel additive: the methanol complex with 2,5-dimethylfuran

Supplementary files

Article information

Article type
Paper
Submitted
04 Aug 2016
Accepted
14 Sep 2016
First published
21 Sep 2016
This article is Open Access
Creative Commons BY license

Phys. Chem. Chem. Phys., 2016,18, 27265-27271

Subtle solvation behaviour of a biofuel additive: the methanol complex with 2,5-dimethylfuran

A. Poblotzki, J. Altnöder and M. A. Suhm, Phys. Chem. Chem. Phys., 2016, 18, 27265 DOI: 10.1039/C6CP05413G

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