Observation of a Zundel-like transition state during proton transfer in hydroxide solutions
It is generally accepted that the anomalous diffusion of the aqueous hydroxide ion results from its ability to accept a proton from a neighboring water molecule; yet, many questions exist concerning the mechanism for this process. What is the solvation structure of the hydroxide ion? In what way do...
| Main Authors: | , , , , , |
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| Other Authors: | |
| Format: | Article |
| Language: | en_US |
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United States National Academy of Sciences
2010
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| Online Access: | http://hdl.handle.net/1721.1/55305 |
| _version_ | 1826197291108663296 |
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| author | Tokmakoff, Andrei Ramasesha, Krupa Petersen, Poul B. Roberts, Sean Thomas Martinez, Todd J. Ufimtsev, Ivan S. |
| author2 | Massachusetts Institute of Technology. Department of Chemistry |
| author_facet | Massachusetts Institute of Technology. Department of Chemistry Tokmakoff, Andrei Ramasesha, Krupa Petersen, Poul B. Roberts, Sean Thomas Martinez, Todd J. Ufimtsev, Ivan S. |
| author_sort | Tokmakoff, Andrei |
| collection | MIT |
| description | It is generally accepted that the anomalous diffusion of the aqueous hydroxide ion results from its ability to accept a proton from a neighboring water molecule; yet, many questions exist concerning the mechanism for this process. What is the solvation structure of the hydroxide ion? In what way do water hydrogen bond dynamics influence the transfer of a proton to the ion? We present the results of femtosecond pump-probe and 2D infrared experiments that probe the O-H stretching vibration of a solution of dilute HOD dissolved in NaOD/D[subscript 2]O. Upon the addition of NaOD, measured pump-probe transients and 2D IR spectra show a new feature that decays with a 110-fs time scale. The calculation of 2D IR spectra from an empirical valence bond molecular dynamics simulation of a single NaOH molecule in a bath of H[subscript 2]O indicates that this fast feature is due to an overtone transition of Zundel-like H[subscript 3]O[subscript 2]− states, wherein a proton is significantly shared between a water molecule and the hydroxide ion. Given the frequency of vibration of shared protons, the observations indicate the shared proton state persists for 2–3 vibrational periods before the proton localizes on a hydroxide. Calculations based on the EVB-MD model argue that the collective electric field in the proton transfer direction is the appropriate coordinate to describe the creation and relaxation of these Zundel-like transition states. |
| first_indexed | 2024-09-23T10:45:47Z |
| format | Article |
| id | mit-1721.1/55305 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T10:45:47Z |
| publishDate | 2010 |
| publisher | United States National Academy of Sciences |
| record_format | dspace |
| spelling | mit-1721.1/553052022-09-27T14:47:09Z Observation of a Zundel-like transition state during proton transfer in hydroxide solutions Tokmakoff, Andrei Ramasesha, Krupa Petersen, Poul B. Roberts, Sean Thomas Martinez, Todd J. Ufimtsev, Ivan S. Massachusetts Institute of Technology. Department of Chemistry Tokmakoff, Andrei Tokmakoff, Andrei Ramasesha, Krupa Petersen, Poul B. Roberts, Sean Thomas It is generally accepted that the anomalous diffusion of the aqueous hydroxide ion results from its ability to accept a proton from a neighboring water molecule; yet, many questions exist concerning the mechanism for this process. What is the solvation structure of the hydroxide ion? In what way do water hydrogen bond dynamics influence the transfer of a proton to the ion? We present the results of femtosecond pump-probe and 2D infrared experiments that probe the O-H stretching vibration of a solution of dilute HOD dissolved in NaOD/D[subscript 2]O. Upon the addition of NaOD, measured pump-probe transients and 2D IR spectra show a new feature that decays with a 110-fs time scale. The calculation of 2D IR spectra from an empirical valence bond molecular dynamics simulation of a single NaOH molecule in a bath of H[subscript 2]O indicates that this fast feature is due to an overtone transition of Zundel-like H[subscript 3]O[subscript 2]− states, wherein a proton is significantly shared between a water molecule and the hydroxide ion. Given the frequency of vibration of shared protons, the observations indicate the shared proton state persists for 2–3 vibrational periods before the proton localizes on a hydroxide. Calculations based on the EVB-MD model argue that the collective electric field in the proton transfer direction is the appropriate coordinate to describe the creation and relaxation of these Zundel-like transition states. 2010-05-27T18:54:53Z 2010-05-27T18:54:53Z 2009-07 2009-02 Article http://purl.org/eprint/type/JournalArticle 1091-6490 0027-8424 http://hdl.handle.net/1721.1/55305 Roberts, Sean T et al. “Observation of a Zundel-like transition state during proton transfer in aqueous hydroxide solutions.” Proceedings of the National Academy of Sciences 106.36 (2009): 15154-15159. © 2009 National Academy of Sciences en_US http://dx.doi.org/10.1073/pnas.0901571106 Proceedings of the National Academy of Sciences of the United States of America Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf United States National Academy of Sciences PNAS |
| spellingShingle | Tokmakoff, Andrei Ramasesha, Krupa Petersen, Poul B. Roberts, Sean Thomas Martinez, Todd J. Ufimtsev, Ivan S. Observation of a Zundel-like transition state during proton transfer in hydroxide solutions |
| title | Observation of a Zundel-like transition state during proton transfer in hydroxide solutions |
| title_full | Observation of a Zundel-like transition state during proton transfer in hydroxide solutions |
| title_fullStr | Observation of a Zundel-like transition state during proton transfer in hydroxide solutions |
| title_full_unstemmed | Observation of a Zundel-like transition state during proton transfer in hydroxide solutions |
| title_short | Observation of a Zundel-like transition state during proton transfer in hydroxide solutions |
| title_sort | observation of a zundel like transition state during proton transfer in hydroxide solutions |
| url | http://hdl.handle.net/1721.1/55305 |
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