近日，美国耶鲁大学Mark A. Johnson团队研究了微水合4-氨基苯甲酸中水介导质子转移的微典型动力学。相关论文发表在2025年9月11日出版的《科学》杂志上。

孤立的高温计系统可以帮助阐明水介导的质子转移的分子水平描述。中性4-氨基苯甲酸（4ABA）的质子化发生在酸（o -原聚体）和胺（n -原聚体）官能团上，产生两种不同的物质，其相对能量取决于水化程度。

研究组对低温离子阱中分离出的初始冷态（6 K）团簇离子进行了单体选择性振动激发，并测量了4ABAH⁺·(H₂O)₆离子中的分子内质子转移速率。在微秒时间尺度上观察到了互变速率。这些结果量化了在封闭、有限系统内，在明确界定的内能条件下质子转移的动力学，因此为正在开发的理论工作提供了实验基准，这些理论工作旨在处理相对缓慢、高度协同的溶剂介导化学过程。

附：英文原文

Title: Microcanonical kinetics of water-mediated proton transfer in microhydrated 4-aminobenzoic acid

Author: Abhijit Rana, Payten A. Harville, Thien Khuu, Mark A. Johnson

Issue&Volume: 2025-09-11

Abstract: Isolated cluster systems can help to elucidate the molecular level description of water-mediated proton transfer. Protonation of neutral 4-aminobenzoic acid (4ABA) occurs at the acid (O-protomer) and amine (N-protomer) functionalities, yielding two distinct species with relative energies dependent on the degree of hydration. Here, we measured the rates of intramolecular proton transfer in 4ABAH+·(H2O)6 ions upon protomer-selective vibrational excitation of initially cold (6 K) cluster ions isolated in a cryogenic ion trap. Interconversion rates were observed on the microsecond time scale. These results quantify the kinetics of proton transfers in the context of a closed, finite system at well-defined internal energies and therefore provide experimental benchmarks for theoretical efforts that are being developed to treat relatively slow, highly cooperative solvent-mediated chemical processes.

DOI: ady1723

Source: https://www.science.org/doi/10.1126/science.ady1723