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Poster Presentations
Day 4, June 25（Wed.）
Room P (Maesato East, Foyer, Ocean Wing)
- 4P-AM-51
Single-Molecule-Mediated Proton Transfer in Protonated Aminocinnamic Acid: Studied by Ion Mobility-CID-Mass Spectrometry
(Tohoku Univ.)
oKengo Tsunoda, Daiki Fuse, Keijiro Ohshimo, Fuminori Misaizu
Protonated p-aminobenzoic acid (PABA·H+) exists as two isomeric forms: the N-protomer, where the proton resides on the nitrogen of the amino group, and the O-protomer, where it is attached to the oxygen of the carboxyl group. Ion mobility–mass spectrometry (IM–MS) separates these species based on their collision cross sections (CCSs). We previously showed that bimolecular collisions of PABA·H+ with ammonia induce a proton transfer reaction from the N-protomer to the O-protomer. In this study, we extended our investigation to protonated aminocinnamic acid (ACA·H+), which features a greater spacing between its amino and carboxyl groups. While a similar proton transfer occurs in ACA·H+, both O- and C-protomers can form; however, these isomers cannot be resolved due to nearly identical CCSs. Consequently, CID was employed after ion mobility analysis to identify reaction products based on their fragmentation patterns. CID experiments revealed that H2O is released at lower collision energies, followed by CO loss at higher energies. Calculations revealed a lower barrier for H2O loss from the O-protomer than from the C-protomer, thereby favoring its predominant formation in ACA·H+ proton transfer. These findings enhance our understanding of proton transfer and inform the design of novel proton transfer catalysts.