Ultrafast proton transfer of the aqueous phenol radical cation
Proton transfer (PT) reactions are fundamental to numerous chemical and biological processes. While sub-picosecond PT involving electronically excited states has been extensively studied, little is known about ultrafast PT triggered by photoionization. Here, we employ femtosecond optical pump-probe...
| Main Authors: | , , , , , |
|---|---|
| Other Authors: | |
| Format: | Journal Article |
| Language: | English |
| Published: |
2022
|
| Subjects: | |
| Online Access: | https://hdl.handle.net/10356/162229 |
| _version_ | 1826128729788645376 |
|---|---|
| author | Muhammad Shafiq Mohd Yusof Song, Hongwei Debnath, Tushar Lowe, Bethany Yang, Minghui Loh, Zhi-Heng |
| author2 | School of Physical and Mathematical Sciences |
| author_facet | School of Physical and Mathematical Sciences Muhammad Shafiq Mohd Yusof Song, Hongwei Debnath, Tushar Lowe, Bethany Yang, Minghui Loh, Zhi-Heng |
| author_sort | Muhammad Shafiq Mohd Yusof |
| collection | NTU |
| description | Proton transfer (PT) reactions are fundamental to numerous chemical and biological processes. While sub-picosecond PT involving electronically excited states has been extensively studied, little is known about ultrafast PT triggered by photoionization. Here, we employ femtosecond optical pump-probe spectroscopy and quantum dynamics calculations to investigate the ultrafast proton transfer dynamics of the aqueous phenol radical cation (PhOH˙+). Analysis of the vibrational wave packet dynamics reveals unusually short dephasing times of 0.18 ± 0.02 ps and 0.16 ± 0.02 ps for the PhOH˙+ O-H wag and bend frequencies, respectively, suggestive of ultrafast PT occurring on the ∼0.1 ps timescale. The reduced potential energy surface obtained from ab initio calculations shows that PT is barrierless when it is coupled to the intermolecular hindered translation between PhOH˙+ and the proton-acceptor water molecule. Quantum dynamics calculations yield a lifetime of 193 fs for PhOH˙+, in good agreement with the experimental results and consistent with the PT reaction being mediated by the intermolecular O⋯O stretch. These results suggest that photoionization can be harnessed to produce photoacids that undergo ultrafast PT. In addition, they also show that PT can serve as an ultrafast deactivation channel for limiting the oxidative damage potential of radical cations. |
| first_indexed | 2024-10-01T07:29:23Z |
| format | Journal Article |
| id | ntu-10356/162229 |
| institution | Nanyang Technological University |
| language | English |
| last_indexed | 2024-10-01T07:29:23Z |
| publishDate | 2022 |
| record_format | dspace |
| spelling | ntu-10356/1622292023-02-28T20:08:58Z Ultrafast proton transfer of the aqueous phenol radical cation Muhammad Shafiq Mohd Yusof Song, Hongwei Debnath, Tushar Lowe, Bethany Yang, Minghui Loh, Zhi-Heng School of Physical and Mathematical Sciences Science::Chemistry Aqueous Phenols Electronically Excited State Proton transfer (PT) reactions are fundamental to numerous chemical and biological processes. While sub-picosecond PT involving electronically excited states has been extensively studied, little is known about ultrafast PT triggered by photoionization. Here, we employ femtosecond optical pump-probe spectroscopy and quantum dynamics calculations to investigate the ultrafast proton transfer dynamics of the aqueous phenol radical cation (PhOH˙+). Analysis of the vibrational wave packet dynamics reveals unusually short dephasing times of 0.18 ± 0.02 ps and 0.16 ± 0.02 ps for the PhOH˙+ O-H wag and bend frequencies, respectively, suggestive of ultrafast PT occurring on the ∼0.1 ps timescale. The reduced potential energy surface obtained from ab initio calculations shows that PT is barrierless when it is coupled to the intermolecular hindered translation between PhOH˙+ and the proton-acceptor water molecule. Quantum dynamics calculations yield a lifetime of 193 fs for PhOH˙+, in good agreement with the experimental results and consistent with the PT reaction being mediated by the intermolecular O⋯O stretch. These results suggest that photoionization can be harnessed to produce photoacids that undergo ultrafast PT. In addition, they also show that PT can serve as an ultrafast deactivation channel for limiting the oxidative damage potential of radical cations. Ministry of Education (MOE) Nanyang Technological University Published version We acknowledge financial support from the Ministry of Education, Singapore (grant no. RG1/20, RG105/17 and MOE2014-T2- 2-052). M. S. B.M. Y. is supported by the Nanyang President’s Graduate Scholarship. H. S. and M. Y. are supported by the National Natural Science Foundation of China (grant no. 21973109 to H. S., and 21773297, 21973108 and 21921004 to M.Y.). 2022-10-10T07:37:08Z 2022-10-10T07:37:08Z 2022 Journal Article Muhammad Shafiq Mohd Yusof, Song, H., Debnath, T., Lowe, B., Yang, M. & Loh, Z. (2022). Ultrafast proton transfer of the aqueous phenol radical cation. Physical Chemistry Chemical Physics, 24(20), 12236-12248. https://dx.doi.org/10.1039/D2CP00505K 1463-9076 https://hdl.handle.net/10356/162229 10.1039/D2CP00505K 20 24 12236 12248 en RG1/20 RG105/17 MOE2014-T2-2-052 Physical Chemistry Chemical Physics © 2022 the Owner Societies. This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. application/pdf |
| spellingShingle | Science::Chemistry Aqueous Phenols Electronically Excited State Muhammad Shafiq Mohd Yusof Song, Hongwei Debnath, Tushar Lowe, Bethany Yang, Minghui Loh, Zhi-Heng Ultrafast proton transfer of the aqueous phenol radical cation |
| title | Ultrafast proton transfer of the aqueous phenol radical cation |
| title_full | Ultrafast proton transfer of the aqueous phenol radical cation |
| title_fullStr | Ultrafast proton transfer of the aqueous phenol radical cation |
| title_full_unstemmed | Ultrafast proton transfer of the aqueous phenol radical cation |
| title_short | Ultrafast proton transfer of the aqueous phenol radical cation |
| title_sort | ultrafast proton transfer of the aqueous phenol radical cation |
| topic | Science::Chemistry Aqueous Phenols Electronically Excited State |
| url | https://hdl.handle.net/10356/162229 |
| work_keys_str_mv | AT muhammadshafiqmohdyusof ultrafastprotontransferoftheaqueousphenolradicalcation AT songhongwei ultrafastprotontransferoftheaqueousphenolradicalcation AT debnathtushar ultrafastprotontransferoftheaqueousphenolradicalcation AT lowebethany ultrafastprotontransferoftheaqueousphenolradicalcation AT yangminghui ultrafastprotontransferoftheaqueousphenolradicalcation AT lohzhiheng ultrafastprotontransferoftheaqueousphenolradicalcation |