Real-time observation of photoionization-induced water migration dynamics in 4-methylformanilide–water by picosecond time-resolved infrared spectroscopy and <i>ab initio</i> molecular dynamics simulations

Miyazaki, Mitsuhiko; Kamiya, Tairiku; Wohlgemuth, Matthias; Chatterjee, Kuntal; Mitrić, Roland; Dopfer, Otto; Fujii, Masaaki

doi:10.1039/d1cp03327a

Cited by 8 publications

(11 citation statements)

References 62 publications

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“…A comparison with tandem mass-based UV–vis absorption action spectroscopy − would further confirm their dissociation patterns. Moreover, time-resolved pump–probe investigations − are also highly demanded to shed light on their photodissociation dynamics. The insights on these microsolvated pyruvate anions, when combining with previous studies of pyruvic acid and the pyruvate anion in the gas and condensed phases, will surely pave a way for a better understanding of all possible reaction mechanisms related to different forms of pyruvic acid at various environmental settings.…”

Section: Discussionmentioning

confidence: 99%

Annihilating Actinic Photochemistry of the Pyruvate Anion by One and Two Water Molecules

Cao

Peng

et al. 2022

J. Am. Chem. Soc.

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Photochemical behaviors of pyruvic acid in multiple phases have been extensively studied, while those of its conjugate base, the pyruvate anion (CH3COCOO–, PA–) are less understood and remain contradictory in gaseous versus aqueous phases. Here in this article, we report a joint experimental and theoretical study combining cryogenic, wavelength-resolved negative ion photoelectron spectroscopy (NIPES) and high-level quantum chemical computations to investigate PA– actinic photochemistry and its dependence on microsolvation in the gas phase. PA–·nH2O (n = 0–5) clusters were generated and characterized, with their low-lying isomers identified. NIPES conducted at multiple wavelengths across the PA– actinic regime revealed the PA– photochemistry extremely sensitive to its hydration extent. While bare PA– anions exhibit active photoinduced dissociations that generate the acetyl (CH3CO–), methide (CH3 –) anions, their corresponding radicals, and slow electrons, one single attached water molecule results in significant suppression with a subsequent second water being able to completely block all dissociation pathways, effectively annihilating all PA– photochemical reactivities. The underlying dissociation mechanisms of PA–·nH2O (n = 0–2) clusters are proposed involving nπ* excitation, dehydration, decarboxylation, and further CO loss. Since the photoexcited dihydrate does not have sufficient energy to overcome the full dehydration barrier before PA– could fragmentate, the PA– dissociation pathway is completely blocked, with the energy most likely released via loss of one water and internal electronic and vibrational relaxations. The insight unraveled in this work provides a much-needed critical link to connect the seemingly conflicting PA– actinic chemistry between the gas and condensed phases.

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Section: Discussionmentioning

confidence: 99%

Annihilating Actinic Photochemistry of the Pyruvate Anion by One and Two Water Molecules

Cao

Peng

et al. 2022

J. Am. Chem. Soc.

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“…6). 95–99 Therefore, this method is only applicable to thin films, so when using RT-FTIR, it is not possible to obtain information, e.g. , about the kinetics of rheological changes in the composition, changes in volume due to the expansion or contraction of the polymer network or changes in crosslinking density along with the sample thickness profile.…”

Section: Quantitative Methods For Monitoring Photopolymerization Reac...mentioning

confidence: 99%

Review of quantitative and qualitative methods for monitoring photopolymerization reactions

et al. 2023

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“…To shed light on the mechanism of the hydration dynamics of multiply hydrated systems, real-time observation of the dynamics is required, for example by picosecond time-resolved IR spectroscopy and MD simulations at a suitable level. [35,[38][39][40]…”

Section: Chemistry-a European Journalmentioning

confidence: 99%

“…The former aspect provides the driving force for the migration, while the latter factor controls accumulation and dissipation of the reaction energy in the reaction coordinate. [39,41] Although the role of solute-solvent interactions can be deduced from these studies, these singly hydrated systems lack any solvent-solvent interaction. The relative strength of solute-solvent and solventsolvent interactions controls for example (i) the competition between single and multiple ligand migration and (ii) IVR into the solvent cluster.…”

Section: Introductionmentioning

confidence: 99%

Hydration Rearrangement in the 4‐Aminobenzonitrile−(H₂O)₂ Cluster Induced by Photoionization: The Effect of Solvent‐Solvent Interactions

Matsuno

Dopfer

Fujii

et al. 2023

Chemistry A European J

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The interplay between solute-solvent and solventsolvent interactions plays an essential role in solvation dynamics that has important effects on the mechanism and dynamics of chemical reactions in solution. In this study, the rearrangement of the hydration shell induced by photoionization of a solute molecule is probed in a state-and isomer-specific manner by resonant multiphoton ionization detected IR spectroscopy of the prototypical 4-aminobenzonitrileÀ (H 2 O) 2 cluster produced in a molecular beam. IR spectra reveal that the water molecules form a cyclic solvent network around the CN group in the initial neutral state (S 0 ). Different from the singly-hydrated cluster, in which either the CN or the NH 2 group is hydrated, hydration of the NH 2 group is not observed in the dihydrated cluster. IR spectra obtained after ionizing the solute molecule into the cation ground state (D 0 ) exhibit features ascribed to both NHbound and CN-bound isomers, indicating that water molecules migrate from the CN to the NH site upon ionization with a yield depending on the ionization excess energy.Analysis of the IR spectra as a function of the excess energy shows that migration produces two different NH 2 solvated structures, namely (i) the most stable structure in which both NÀ H bonds are singly hydrated and (ii) the second most stable isomer in which one of the NÀ H bonds is hydrated by a H-bonded (H 2 O) 2 dimer. The product branching ratio of the two isomers depends on the excess energy. The role of the water-water interaction in the hydration rearrangement is discussed based on the potential energy landscape. Solvation dynamics plays an important role in reaction mechanisms in the condensed phase, where not only solute-solvent solvation but also solvent-solvent interactions have a significant influence on the dynamics. Thus, the investigation of solvation dynamics at the molecular level substantially contributes to our understanding of the reaction mechanism. In this study, the dihydrated cluster of 4ABN was utilized as a model for the first solvation layer to elucidate solvent motions induced by ionization of the solute and the role of WÀ W interactions for the solvent relaxation.

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Real-time observation of photoionization-induced water migration dynamics in 4-methylformanilide–water by picosecond time-resolved infrared spectroscopy and ab initio molecular dynamics simulations

Abstract: A novel time-resolved pump-probe spectroscopic approach that enables to keep high resolution in both the time and energy domain, nanosecond excitation-picosecond ionization-picosecond infrared probe (ns-ps-ps TRIR) spectroscopy, has been applied...

Cited by 8 publications

References 62 publications

Annihilating Actinic Photochemistry of the Pyruvate Anion by One and Two Water Molecules

Annihilating Actinic Photochemistry of the Pyruvate Anion by One and Two Water Molecules

Review of quantitative and qualitative methods for monitoring photopolymerization reactions

Hydration Rearrangement in the 4‐Aminobenzonitrile−(H₂O)₂ Cluster Induced by Photoionization: The Effect of Solvent‐Solvent Interactions

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Real-time observation of photoionization-induced water migration dynamics in 4-methylformanilide–water by picosecond time-resolved infrared spectroscopy and ab initio molecular dynamics simulations

Abstract: A novel time-resolved pump-probe spectroscopic approach that enables to keep high resolution in both the time and energy domain, nanosecond excitation-picosecond ionization-picosecond infrared probe (ns-ps-ps TRIR) spectroscopy, has been applied...

Cited by 8 publications

References 62 publications

Annihilating Actinic Photochemistry of the Pyruvate Anion by One and Two Water Molecules

Annihilating Actinic Photochemistry of the Pyruvate Anion by One and Two Water Molecules

Review of quantitative and qualitative methods for monitoring photopolymerization reactions

Hydration Rearrangement in the 4‐Aminobenzonitrile−(H2O)2 Cluster Induced by Photoionization: The Effect of Solvent‐Solvent Interactions

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Hydration Rearrangement in the 4‐Aminobenzonitrile−(H₂O)₂ Cluster Induced by Photoionization: The Effect of Solvent‐Solvent Interactions