NMR and DFT study on media effects on proton transfer in hydrogen bonding: concept of molecular probe with an application to ionic and super-polar liquids

文献情報

出版日 2009-07-27

DOI 10.1039/B819666D

インパクトファクター 3.676

著者

Vytautas Balevicius, Zofia Gdaniec, Kestutis Aidas

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要旨

Media effects of ionic and super-polar liquids on the state of H-bonding were studied by NMR and DFT methods. The proton sharing (positioning) in the H-bond was monitored following the chemical shifts of picolinic acid N-oxide (PANO) used as the molecular probe. The relationships between PANO1H and 13C chemical shifts and proton position in the O–H⋯O bridge were calibrated using traditional organic solvents and other H-bond complexes of pyridine N-oxide with acids to increase the H-bond strength. A reliable parameter for H-bond monitoring was proposed. The state of the H-bond in ionic liquid media is largely governed by the dielectric properties of the bulk media. A drastic fall-out of PANO/[BuMePyr][TfO] from the general dielectric scheme built using solvents with increasing dielectric constant (from chloroform to water and culminating with formamide) was observed. On a molecular level this effect indicates that the ionic liquid [BuMePyr][TfO] can act on H-bonded systems as a stimulant of proton transfer. In ‘super-polar’ media (formamide) the intramolecular H-bond system converts into an intermolecular one forming a neutral H-bond complex of PANO with the formamide molecule.

掲載誌

Physical Chemistry Chemical Physics

CiteScore: 5.5

自己引用率: 10.3%

年間論文数: 3036

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