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Huo J, Chen J, Liu P, Hong B, Zhang J, Dong H, Li S. Microscopic Mechanism of Proton Transfer in Pure Water under Ambient Conditions. J Chem Theory Comput 2023. [PMID: 37365994 DOI: 10.1021/acs.jctc.3c00244] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/28/2023]
Abstract
Water molecules and the associated proton transfer (PT) are prevalent in chemical and biological systems and have been a hot research topic. Spectroscopic characterization and ab initio molecular dynamics (AIMD) simulations have previously revealed insights into acidic and basic liquids. Presumably, the situation in the acidic/basic solution is not necessarily the same as in pure water; in addition, the autoionization constant for water is only 10-14 under ambient conditions, making the study of PT in pure water challenging. To overcome this issue, we modeled periodic water box systems containing 1000 molecules for tens of nanoseconds based on a neural network potential (NNP) with quantum mechanical accuracy. The NNP was generated by training a dataset containing the energies and atomic forces of 17 075 configurations of periodic water box systems, and these data points were calculated at the MP2 level that considers electron correlation effects. We found that the size of the system and the duration of the simulation have a significant impact on the convergence of the results. With these factors considered, our simulations showed that hydronium (H3O+) and hydroxide (OH-) ions in water have distinct hydration structures, thermodynamic and kinetic properties, e.g., the longer-lasting and more stable hydrated structure of OH- ions than that of H3O+, as well as a significantly higher free energy barrier for the OH--associated PT than that of H3O+, leading the two to exhibit completely different PT behaviors. Given these characteristics, we further found that PT via OH- ions tends not to occur multiple times or between many molecules. In contrast, PT via H3O+ can synergistically occur among multiple molecules and prefers to adopt a cyclic pattern among three water molecules, while it occurs mostly in a chain pattern when more water molecules are involved. Therefore, our studies provide a detailed and solid microscopic explanation for the PT process in pure water.
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Affiliation(s)
- Jun Huo
- Kuang Yaming Honors School, Nanjing University, Nanjing 210023, China
| | - Jianghao Chen
- Kuang Yaming Honors School, Nanjing University, Nanjing 210023, China
- School of Physics, National Laboratory of Solid State Microstructure, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Pei Liu
- School of Chemistry and Chemical Engineering, Key Laboratory of Mesoscopic Chemistry of Ministry of Education, Institute of Theoretical and Computational Chemistry, Nanjing University, Nanjing 210023, China
| | - Benkun Hong
- School of Chemistry and Chemical Engineering, Key Laboratory of Mesoscopic Chemistry of Ministry of Education, Institute of Theoretical and Computational Chemistry, Nanjing University, Nanjing 210023, China
| | - Jian Zhang
- School of Physics, National Laboratory of Solid State Microstructure, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Hao Dong
- Kuang Yaming Honors School, Nanjing University, Nanjing 210023, China
- State Key Laboratory of Analytical Chemistry for Life Science, Nanjing University, Nanjing 210023, China
- Institute for Brain Sciences, Nanjing University, Nanjing 210023, China
| | - Shuhua Li
- School of Chemistry and Chemical Engineering, Key Laboratory of Mesoscopic Chemistry of Ministry of Education, Institute of Theoretical and Computational Chemistry, Nanjing University, Nanjing 210023, China
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Garofalini SH, Lentz J. Subpicosecond Molecular Rearrangements Affect Local Electric Fields and Auto-Dissociation in Water. J Phys Chem B 2023; 127:3392-3401. [PMID: 37036747 DOI: 10.1021/acs.jpcb.2c06490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
Abstract
Molecular simulations of auto-dissociation of water molecules in an 81,000 atom bulk water system show that the electric field variations caused by local bond length and angle variations enhance proton transfer within ∼600 fs prior to auto-dissociation. In this paper, auto-dissociation relates to the initial separation of a proton from a water molecule to another, forming the H33O+ and OH- ions. Only transfers for which a proton's initial nearest covalently bonded oxygen remained the same for at least 1 ps prior to the transfer and for which that proton's new nearest acceptor oxygen remained the same for at least 1 ps after the transfer were evaluated. Electric fields from solvent atoms within 6 Å of a transferring proton (H*) are dominant, with little contribution from farther molecules. However, exclusion of the accepting oxygen in such electric field calculations shows that the field on H* from the other solvent atoms weakens as the time to transfer becomes less than 600 fs, indicating the primary importance of the accepting oxygen on enabling auto-dissociation. All resultant OH- and H3O+ ion pairs recombined at times greater than 1 ps after auto-dissociation. A concentration of 8.01 × 1017 cm-3 for these ion pairs was observed. The simulations indicate that transient auto-dissociation in water is more common than that inferred from dc-conductivity experiments (10-5 vs 10-7) and is consistent with the results of calculations that include nuclear quantum effects. The conductivity experiments require the rearrangement of farther water molecules to form hydrogen-bonded "water wires" that afford long-range and measurable proton transport away from the reaction site. Nonetheless, the relatively large number of picosecond-lived auto-dissociation products might be engineered within 2D layers and oriented external fields to offer new energy-related systems.
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Affiliation(s)
- Stephen H Garofalini
- Department of Matserials Science and Engineering, Rutgers University, 607 Taylor Road, Piscataway, New Jersey 08855, United States
| | - Jesse Lentz
- Department of Matserials Science and Engineering, Rutgers University, 607 Taylor Road, Piscataway, New Jersey 08855, United States
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Cao Y, Meng Y, Wu Y, Shen Z, Xia Q, Huang H, Lang JP, Gu H, Wang Y, Li X. Regulation of the Coordination Structures of Transition Metals on Nitrogen-Doped Carbon Nanotubes for Electrochemical CO 2 Reduction. Inorg Chem 2022; 61:18957-18969. [DOI: 10.1021/acs.inorgchem.2c03221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Yongyong Cao
- College of Biological, Chemical Science and Engineering, Jiaxing University, Jiaxing, Zhejiang 314001, P. R. China
| | - Yuxiao Meng
- College of Biological, Chemical Science and Engineering, Jiaxing University, Jiaxing, Zhejiang 314001, P. R. China
- Institute of Industrial Catalysis, College of Chemical Engineering, State Key Laboratory Breeding Base of Green-Chemical Synthesis Technology, Zhejiang University of Technology, Hangzhou, Zhejiang 310032, P. R. China
| | - Yuting Wu
- College of Biological, Chemical Science and Engineering, Jiaxing University, Jiaxing, Zhejiang 314001, P. R. China
| | - Zhangfeng Shen
- College of Biological, Chemical Science and Engineering, Jiaxing University, Jiaxing, Zhejiang 314001, P. R. China
| | - Qineng Xia
- College of Biological, Chemical Science and Engineering, Jiaxing University, Jiaxing, Zhejiang 314001, P. R. China
| | - Hong Huang
- College of Biological, Chemical Science and Engineering, Jiaxing University, Jiaxing, Zhejiang 314001, P. R. China
| | - Jian-Ping Lang
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, Jiangsu 215123, P. R. China
| | - Hongwei Gu
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, Jiangsu 215123, P. R. China
| | - Yangang Wang
- College of Biological, Chemical Science and Engineering, Jiaxing University, Jiaxing, Zhejiang 314001, P. R. China
| | - Xi Li
- College of Biological, Chemical Science and Engineering, Jiaxing University, Jiaxing, Zhejiang 314001, P. R. China
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