Solvent reorganization triggers photo-induced solvated electron generation in phenol

Sandler, Isolde; Nogueira, Juan J.; González, Leticia

doi:10.1039/c8cp06656f

Cited by 7 publications

(5 citation statements)

References 91 publications

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“…For the QM/EFP calculations, the QM region was selected to be phenol plus the ve water molecules closest to any atom within phenol. Although fewer water molecules have been employed for other calculations of phenol in aqueous solution, 34,43 we used ve because we found this was enough to ensure that all the water molecules that are hydrogen-bonded to phenol (donor-acceptor distance < 3Å, donor-H-acceptor bond angle 180 AE 20 ) were included in the QM region. The EFP region was selected to be all other water molecules within 10Å of any atom in the phenol molecule (250-300 water molecules).…”

Section: Computationalmentioning

confidence: 99%

An experimental and computational study of the effect of aqueous solution on the multiphoton ionisation photoelectron spectrum of phenol

et al. 2020

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We revisit the photoelectron spectroscopy of aqueous phenol in an effort to improve our understanding of the impact of inhomogeneous broadening and inelastic scattering on solution-phase photoelectron spectra. Following resonance-enhanced multiphoton ionisation via the 1 1 pp* and 1 1 ps* states of phenol, we observe 1 1 pp*-D 0 /D 1 ionisation and competing direct S 0 -D 0 /D 1 ionisation. Following resonance-enhanced multiphoton ionisation via the 2 1 pp* state, we observe the signature of solvated electrons. By comparing the photoelectron spectra of aqueous phenol with those of gas-phase phenol, we find that inelastic scattering results in peak shifts with similar values to those that have been observed in photoelectron spectra of solvated electrons, highlighting the need for a robust way of deconvoluting the effect of inelastic scattering from liquid-phase photoelectron spectra. We also present a computational strategy for calculating vertical ionisation energies using a quantum-mechanics/effective fragmentation potential (QM/EFP) approach, in which we find that optimising the configurations obtained from molecular dynamics simulations and using the [phenol$(H 2 O) 5 ] QM [(H 2 O) n$250 ] EFP (B3LYP/aug-cc-pvdz) method gives good agreement with experiment. Electronic supplementary information (ESI) available: Streaming potential measurement; photoelectron spectra plotted as a function of eKE; details of tting procedures; convergence of VIE; tables of calculated and experimental VIEs and VEEs; selection of probable congurations; consistencies between soware packages; molecular orbitals; coordinates of QM region. See

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Section: Computationalmentioning

confidence: 99%

An experimental and computational study of the effect of aqueous solution on the multiphoton ionisation photoelectron spectrum of phenol

et al. 2020

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“…Gonzalez and co-workers carried out computational studies of the related heteroatomic molecule phenol microsolvated by 15 water molecules, and they described the presence of a charge-transfer (CT) state: an electron promoted from an π orbital on phenol to a σ*-type orbital located in the solvent. The calculations returned very low oscillator strengths for the CT state and showed that the CT minimum is lower in energy than that of the optically bright 1 ππ* state . We propose that the aforementioned theoretical discussion of CTTS or CT states in related heteroaromatics molecules is another way of describing, or even synonymous with, a tightly bound cation–electron contact ion-pair, , e.g., [Ind + :e – ], where the surfaces of the cation and electron are in direct contact with no solvent molecules in between.…”

Section: Discussionmentioning

confidence: 88%

“…The calculations returned very low oscillator strengths for the CT state and showed that the CT minimum is lower in energy than that of the optically bright 1 ππ* state. 76 We propose that the aforementioned theoretical discussion of CTTS or CT states in related heteroaromatics molecules is another way of describing, or even synonymous with, a tightly bound cation–electron contact ion-pair, 63 , 77 e.g., [Ind + :e – ], where the surfaces of the cation and electron are in direct contact with no solvent molecules in between.…”

Section: Discussionmentioning

confidence: 99%

Unraveling the Photoionization Dynamics of Indole in Aqueous and Ethanol Solutions

Kumar,

Kellogg,

Dey

et al. 2024

J. Phys. Chem. B

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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 1 ππ* 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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“…Excitation energies are shown in Table . There are many studies of electronic excitations of phenol. − An experimental adsorption wavelength for the lowest singlet (π → π*) is 267 nm (4.644 eV) . An overlay of the ground and excited state optimized structures of phenol is shown in Figure .…”

Section: Resultsmentioning

confidence: 99%

Analytic Gradient for Time-Dependent Density Functional Theory Combined with the Fragment Molecular Orbital Method

Nakata

Fedorov

2023

J. Chem. Theory Comput.

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The analytic energy gradient of energy with respect to nuclear coordinates is derived for the fragment molecular orbital (FMO) method combined with time-dependent density functional theory (TDDFT). The response terms arising from the use of a polarizable embedding are derived. The obtained analytic FMO-TDDFT gradient is shown to be accurate in comparison to both numerical FMO-TDDFT and unfragmented TDDFT gradients, at the level of two- and three-body expansions. The gradients are used for geometry optimizations, molecular dynamics, vibrational calculations, and simulations of IR and Raman spectra of excited states. The developed method is used to optimize the geometry of the ground and excited electronic states of the photoactive yellow protein (PDB: 2PHY).

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Solvent reorganization triggers photo-induced solvated electron generation in phenol

Abstract: Charge-transfer states with large electron–hole separation, correlating to the formation of solvated electrons, are found below the maximum of the absorbing ππ* band of solvated phenol.

Cited by 7 publications

References 91 publications

An experimental and computational study of the effect of aqueous solution on the multiphoton ionisation photoelectron spectrum of phenol

An experimental and computational study of the effect of aqueous solution on the multiphoton ionisation photoelectron spectrum of phenol

Unraveling the Photoionization Dynamics of Indole in Aqueous and Ethanol Solutions

Analytic Gradient for Time-Dependent Density Functional Theory Combined with the Fragment Molecular Orbital Method

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