Steady-state spectroscopy to single out the contact ion pair in excited-state proton transfer

• Verfasst von: Grandjean, Alexander [VerfasserIn]
• Verfasst von: Pérez Lustres, José Luis [VerfasserIn]
• Verfasst von: Muth, Stephan [VerfasserIn]
• Verfasst von: Maus, Daniel [VerfasserIn]
• Verfasst von: Jung, Gregor [VerfasserIn]
• Titel: Steady-state spectroscopy to single out the contact ion pair in excited-state proton transfer
• Verf.angabe: Alexander Grandjean, J. Luis Pérez Lustres, Stephan Muth, Daniel Maus, and Gregor Jung
• E-Jahr: 2021
• Jahr: February 9, 2021
• Umfang: 7 S.
• Teil: volume:12
• Teil: year:2021
• Teil: number:6
• Teil: pages:1683-1689
• Teil: extent:7
• Fussnoten: Gesehen am 09.09.2021
• Titel Quelle: Enthalten in: The journal of physical chemistry letters
• Ort Quelle: Washington, DC : ACS, 2010
• Jahr Quelle: 2021
• Band/Heft Quelle: 12(2021), 6, Seite 1683-1689
• ISSN Quelle: 1948-7185
• DOI: doi:10.1021/acs.jpclett.0c03593
• Datenträger: Online-Ressource
• Sprache: eng
• K10plus-PPN: 1753143675

Abstract

Despite the outstanding relevance of proton transfer reactions, investigations of the solvent dependence on the elementary step are scarce. We present here a probe system of a pyrene-based photoacid and a phosphine oxide, which forms stable hydrogen-bonded complexes in aprotic solvents of a broad polarity range. By using a photoacid, an excited-state proton transfer (ESPT) along the hydrogen bond can be triggered by a photon and observed via fluorescence spectroscopy. Two emission bands could be identified and assigned to the complexed photoacid (CPX) and the hydrogen-bonded ion pair (HBIP) by a solvatochromism analysis based on the Lippert-Mataga model. The latter indicates that the difference in the change of the permanent dipole moment of the two species upon excitation is ∼3 D. This implies a displacement of the acidic hydrogen by ∼65 pm, which is in quantitative agreement with a change of the hydrogen bond configuration from O-H···O to -O···H-O+.