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Tomaník L, Pugini M, Mudryk K, Thürmer S, Stemer D, Credidio B, Trinter F, Winter B, Slavíček P. Liquid-jet photoemission spectroscopy as a structural tool: site-specific acid-base chemistry of vitamin C. Phys Chem Chem Phys 2024. [PMID: 38963770 DOI: 10.1039/d4cp01521e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/06/2024]
Abstract
Liquid-jet photoemission spectroscopy (LJ-PES) directly probes the electronic structure of solutes and solvents. It also emerges as a novel tool to explore chemical structure in aqueous solutions, yet the scope of the approach has to be examined. Here, we present a pH-dependent liquid-jet photoelectron spectroscopic investigation of ascorbic acid (vitamin C). We combine core-level photoelectron spectroscopy and ab initio calculations, allowing us to site-specifically explore the acid-base chemistry of the biomolecule. For the first time, we demonstrate the capability of the method to simultaneously assign two deprotonation sites within the molecule. We show that a large change in chemical shift appears even for atoms distant several bonds from the chemically modified group. Furthermore, we present a highly efficient and accurate computational protocol based on a single structure using the maximum-overlap method for modeling core-level photoelectron spectra in aqueous environments. This work poses a broader question: to what extent can LJ-PES complement established structural techniques such as nuclear magnetic resonance? Answering this question is highly relevant in view of the large number of incorrect molecular structures published.
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Affiliation(s)
- Lukáš Tomaník
- Department of Physical Chemistry, University of Chemistry and Technology, Technická 5, 16628 Prague, Czech Republic.
| | - Michele Pugini
- Molecular Physics, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany.
| | - Karen Mudryk
- Molecular Physics, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany.
| | - Stephan Thürmer
- Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-Ku, 606-8502 Kyoto, Japan
| | - Dominik Stemer
- Molecular Physics, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany.
| | - Bruno Credidio
- Molecular Physics, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany.
| | - Florian Trinter
- Molecular Physics, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany.
| | - Bernd Winter
- Molecular Physics, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany.
| | - Petr Slavíček
- Department of Physical Chemistry, University of Chemistry and Technology, Technická 5, 16628 Prague, Czech Republic.
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Kumar G, Kellogg M, Dey S, Oliver TAA, Bradforth SE. Unraveling the Photoionization Dynamics of Indole in Aqueous and Ethanol Solutions. J Phys Chem B 2024; 128:4158-4170. [PMID: 38655896 DOI: 10.1021/acs.jpcb.4c01223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
The photoionization dynamics of indole, the ultraviolet-B chromophore of tryptophan, were explored in water and ethanol using ultrafast transient absorption spectroscopy with 292, 268, and 200 nm excitation. By studying the femtosecond-to-nanosecond dynamics of indole in two different solvents, a new photophysical model has been generated that explains many previously unsolved facets of indole's complex solution phase photochemistry. Photoionization is only an active pathway for indole in aqueous solution, leading to a reduction in the fluorescence quantum yield in water-rich environments, which is frequently used in biophysical experiments as a key signature of the protein-folded state. Photoionization of indole in aqueous solution was observed for all three pump wavelengths but via two different mechanisms. For 200 nm excitation, electrons are ballistically ejected directly into the bulk solvent. Conversely, 292 and 268 nm excitation populates an admixture of two 1ππ* states, which form a dynamic equilibrium with a tightly bound indole cation and electron-ion pair. The ion pair dissociates on a nanosecond time scale, generating separated solvated electrons and indole cations. The charged species serve as important precursors to triplet indole production and greatly enhance the overall intersystem crossing rate. Our proposed photophysical model for indole in aqueous solution is the most appropriate for describing photoinduced dynamics of tryptophan in polypeptide sequences; tryptophan in aqueous pH 7 solution is zwitterionic, unlike in peptides, and resultantly has a competitive excited state proton transfer pathway that quenches the tryptophan fluorescence.
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Affiliation(s)
- Gaurav Kumar
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Michael Kellogg
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Shivalee Dey
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Thomas A A Oliver
- School of Chemistry, Cantock's Close, University of Bristol, Bristol BS8 1TS, U.K
| | - Stephen E Bradforth
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
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Johny M, Schouder CA, Al-Refaie A, He L, Wiese J, Stapelfeldt H, Trippel S, Küpper J. Water is a radiation protection agent for ionised pyrrole. Phys Chem Chem Phys 2024; 26:13118-13130. [PMID: 38629233 DOI: 10.1039/d3cp03471b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2024]
Abstract
Radiation-induced damage of biological matter is an ubiquitous problem in nature. The influence of the hydration environment is widely discussed, but its exact role remains elusive. Utilising well defined solvated-molecule aggregates, we experimentally observed a hydrogen-bonded water molecule acting as a radiation protection agent for ionised pyrrole, a prototypical aromatic biomolecule. Pure samples of pyrrole and pyrrole(H2O) were outer-valence ionised and the subsequent damage and relaxation processes were studied. Bare pyrrole ions fragmented through the breaking of C-C or N-C covalent bonds. However, for pyrrole(H2O)+, we observed a strong protection of the pyrrole ring through the dissociative release of neutral water or by transferring an electron or proton across the hydrogen bond. Overall, a single water molecule strongly reduces the fragmentation probability and thus the persistent radiation damage of singly-ionised pyrrole.
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Affiliation(s)
- Melby Johny
- Center for Free-Electron Laser Science CFEL, Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany.
- Center for Ultrafast Imaging, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
- Department of Physics, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Constant A Schouder
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000 Aarhus C, Denmark
- LIDYL, CNRS, CEA, Université Paris-Saclay, 91191 Gif-sur-Yvette, France
| | - Ahmed Al-Refaie
- Center for Free-Electron Laser Science CFEL, Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany.
| | - Lanhai He
- Center for Free-Electron Laser Science CFEL, Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany.
| | - Joss Wiese
- Center for Free-Electron Laser Science CFEL, Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany.
- Center for Ultrafast Imaging, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
- Department of Chemistry, Universität Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany
| | - Henrik Stapelfeldt
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000 Aarhus C, Denmark
| | - Sebastian Trippel
- Center for Free-Electron Laser Science CFEL, Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany.
- Center for Ultrafast Imaging, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Jochen Küpper
- Center for Free-Electron Laser Science CFEL, Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany.
- Center for Ultrafast Imaging, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
- Department of Physics, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
- Department of Chemistry, Universität Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany
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Robinson MS, Küpper J. Unraveling the ultrafast dynamics of thermal-energy chemical reactions. Phys Chem Chem Phys 2024; 26:1587-1601. [PMID: 38131437 DOI: 10.1039/d3cp03954d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2023]
Abstract
In this perspective, we discuss how one can initiate, image, and disentangle the ultrafast elementary steps of thermal-energy chemical dynamics, building upon advances in technology and scientific insight. We propose that combinations of ultrashort mid-infrared laser pulses, controlled molecular species in the gas phase, and forefront imaging techniques allow to unravel the elementary steps of general-chemistry reaction processes in real time. We detail, for prototypical first reaction systems, experimental methods enabling these investigations, how to sufficiently prepare and promote gas-phase samples to thermal-energy reactive states with contemporary ultrashort mid-infrared laser systems, and how to image the initiated ultrafast chemical dynamics. The results of such experiments will clearly further our understanding of general-chemistry reaction dynamics.
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Affiliation(s)
- Matthew S Robinson
- Center for Free-Electron Laser Science CFEL, Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany.
- Center for Ultrafast Imaging, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Jochen Küpper
- Center for Free-Electron Laser Science CFEL, Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany.
- Center for Ultrafast Imaging, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
- Department of Physics, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
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