法国巴黎文理研究大学Laage, Damien研究团队报道，基于神经网络的分子动力学模拟揭示质子在水中的传输由顺序氢键交换双重控制。相关研究成果于2024年8月20日发表在《自然—化学》。

水中多余质子的运输是酸碱化学、生物化学和能源生产的核心。然而，阐明其机制一直具有挑战性。最近的非线性振动光谱实验无法用现有的模型来解释。

该文中，研究人员使用振动光谱计算和基于神经网络的分子动力学模拟来确定质子输运机制，这些模拟考虑了所有原子的核量子效应。该模拟揭示了具有不同的本征式和宗德尔式氢键基序的，两个稳定的质子局域化结构之间的平衡。

质子传输遵循由两次连续氢键交换控制的三步机制：第一步减少质子受体-水配位，导致质子转移，第二步是限速步骤，通过增加质子供体配位来防止快速反向转移。这种顺序机制与质子扩散的实验特征一致，解释了振动光谱中的低活化能和延长的中间寿命。

研究结果对于理解生化和技术系统中的质子动力学至关重要。

附：英文原文

Title: Neural-network-based molecular dynamics simulations reveal that proton transport in water is doubly gated by sequential hydrogen-bond exchange

Author: Gomez, Axel, Thompson, Ward H., Laage, Damien

Issue&Volume: 2024-08-20

Abstract: The transport of excess protons in water is central to acid–base chemistry, biochemistry and energy production. However, elucidating its mechanism has been challenging. Recent nonlinear vibrational spectroscopy experiments could not be explained by existing models. Here we use both vibrational spectroscopy calculations and neural-network-based molecular dynamics simulations that account for nuclear quantum effects for all atoms to determine the proton transport mechanism. Our simulations reveal an equilibrium between two stable proton-localized structures with distinct Eigen-like and Zundel-like hydrogen-bond motifs. Proton transport follows a three-step mechanism gated by two successive hydrogen-bond exchanges: the first reduces the proton-acceptor water coordination, leading to proton transfer, and the second, the rate-limiting step, prevents rapid back-transfer by increasing the proton-donor coordination. This sequential mechanism is consistent with experimental characterizations of proton diffusion, explaining the low activation energy and the prolonged intermediate lifetimes in vibrational spectroscopy. These results are crucial for understanding proton dynamics in biochemical and technological systems.

DOI: 10.1038/s41557-024-01593-y

Source: https://www.nature.com/articles/s41557-024-01593-y