Abstract

Poster Presentations

Day 2, June 11（Tue.）　　Room P1 (Multipurpose Hall)・Room P2 (Conference Room 101+102)

Proton transfer reactions are crucial in various fields, from biochemistry to energy conversion technologies. Two mechanisms, the Grotthuss and vehicle mechanisms, are reported for these reactions, involving the relay of protons via water molecules or single-molecule transport. Protonated p-aminobenzoic acid (PABA·H+) has two isomers: N-protonated and O-protonated forms. An NH3 molecule was recently found to transport a proton within PABA (vehicle mechanism). In this study, PABA and its ethyl ester (PABE) were investigated using cryogenic ion mobility-mass spectrometry (Cryo-IM-MS) to observe and identify reaction intermediates. After the reaction in a quadruple ion trap (QIT) at 130 K, a complex ion, PABA∙H+∙NH3, was identified as an NH3 adduct to the O-protonated form in the IM-MS measurement. Reaction rate constants for PABA·H+ and PABE·H+ determined at 300 K had a positive correlation with NH3 binding energies. This research sheds light on the intricate dynamics of proton transfer reactions and their temperature dependence, crucial for understanding various chemical processes and designing efficient energy conversion systems.

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