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オーラルセッション

第3日　6月24日（金）　14:40～15:20　C会場（411，412）

3C-O2-1440　　PDF

イオン移動度質量分析を用いたプロトン付加分子におけるプロトン移動反応の研究

(東北大院理)
^o大下慶次郎・ 佐藤良亮・ 高崎佑也・ 美齊津文典

Two mechanisms of proton transfer are well established; the Grotthuss mechanism (proton-relay) and the vehicle mechanism. Intramolecular proton transfer has been extensively studied in the gas phase to understand the proton transfer mechanism microscopically. However, only the Grotthuss mechanism was proposed so far for intramolecular proton transfer. Here we show the evidence for proton transfer via the vehicle mechanism in a gas-phase protonated molecule. Using ion mobility-mass spectrometry, we observed that a single NH₃ molecule induces intramolecular proton transfer between two structural isomers with different protonation sites of protonated p-aminobenzoic acid (PABA; p–NH₂C₆H₄COOH). In combination with theoretical calculations of the reaction pathway for the bimolecular reaction of PABA·H⁺+NH₃, it was concluded that intramolecular proton transfer to produce the O-protomer (protonated PABA at the C=O group) proceeds in the N-protomer (protonated PABA at the NH₂ group) by NH₃ coordination.