Proton-transfer reaction dynamics

Douhal, Abderrazzak; Lahmani, F.; Zewail, Ahmed H.

doi:10.1016/0301-0104(96)00067-5

Cited by 549 publications

(458 citation statements)

References 56 publications

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“…Vibronic states closer to the S 1 origin are known to have a longer lifetime. 15,28 The proton transfer time of less than 50 fs presented for OHBA and for higher vibronic levels in HAN is very similar to the proton transfer rates of many related systems, e.g., methyl salicylate, 18 2-͑2Ј-hydroxyphenyl͒benzoxazole 33 and TINUVIN P 34 and may be a common time scale for direct ESIPT processes. The observation of signal oscillations by transient absorption experiments on 2-͑2Ј-hydroxyphenyl͒benzothiazole show that the ESIPT is mediated by deformations of the whole chelate ring, 35 in agreement with theoretical work.…”

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confidence: 52%

“…Here we consider the important nonadiabatic process of excited state intramolecular proton transfer ͑ESIPT͒. [14][15][16] Methyl salicylate ͑MS͒ has served as a model system in many studies since fluorescence detection allows for the study of the population dynamics in the excited state tautomers. 17,18 In many systems, however, fluorescence quantum yields can be very small and a more general detection method is needed.…”

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confidence: 99%

“…Proton transfer reactions often proceed via tunnelling of the proton through a barrier. 15,31 Deuteration of the transferred proton should then significantly prolong the lifetime of the S 1 enol tautomer. In experiments with ODBA, we did not observe an isotope effect-i.e., the ESIPT reaction was again complete within the laser cross correlation.…”

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confidence: 99%

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Dynamics of excited-state proton transfer systems via time-resolved photoelectron spectroscopy

Lochbrunner

Schultz

Schmitt

et al. 2001

The Journal of Chemical Physics

156

158

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We investigate the applicability of time-resolved photoelectron spectroscopy to excited state intramolecular proton transfer (ESIPT) and internal conversion dynamics in the model system o-hydroxybenzaldehyde (OHBA) and related compounds. Photoelectron spectra of both the excited state enol and keto tautomers were obtained as a function of pump laser wavelength and pump-probe time delay. The ESIPT was found to occur in less than 50 fs over the whole absorption range of the S1(ππ*) state for both OHBA and its monodeuterated analog, suggestive of a small or nonexistent barrier. The subsequent keto internal conversion rate in OHBA varies from 0.63 to 0.17 ps−1 over the S1(ππ*) absorption band and the OD-deuterated analog shows no significant isotope effect. Based upon ab initio calculations and comparison with the two-ring analog, 1-hydroxy-2-acetonaphthone (HAN), we suggest that the internal conversion dynamics in OHBA is influenced by interactions with a close-lying nπ* state.

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confidence: 52%

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confidence: 99%

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Dynamics of excited-state proton transfer systems via time-resolved photoelectron spectroscopy

Lochbrunner

Schultz

Schmitt

et al. 2001

The Journal of Chemical Physics

156

158

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“…Very recently, Sakota and co-workers measured the dispersed fluorescence (DF) spectra and resonance-enhanced multiphoton ionization (REMPI) spectra for the 7AI-(H 2 O) n (n ) 2, 3) cluster at low temperature in the gas phase and found that the tautomerization of 7AI-(H 2 O) n (n ) 2, 3) occurs in the S 1 state, 21 although it was not observed at first based on the measurement of the fluorescence excitation (FE) and DF spectra. 16 It was also reported 18,19 by the same group that the excited-state triple-Htransfer occurs in the 7AI-(MeOH) 2 cluster, based on the measurement of DF and REMPI spectra, but the tautomerization does not occur in 7AI-MeOH and 7AI-(MeOH) 3 clusters. They pointed out that ESHT in 7AI-(MeOH) 2 proceeds via a tunneling mechanism in their experimental conditions, and the excitation of the low-energy intermolecular stretching mode accelerates ESHT in 7AI-(MeOH) 2 .…”

Section: Introductionmentioning

confidence: 86%

“…[1][2][3] Typically, this type of transfer occurs through a hydrogen-bonded network. 7-Azaindole (7AI) is a molecule in which this process is important.…”

Section: Introductionmentioning

confidence: 99%

Ab Initio QM/MM Molecular Dynamics Study on the Excited-State Hydrogen Transfer of 7-Azaindole in Water Solution

et al. 2008

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Ab initio molecular dynamics (AIMD) simulations for the excited-state hydrogen transfer (ESHT) reaction of 7-azaindole (7AI−(H2O)n; n = 1, 2) clusters in the gas phase and in water are presented. The effective fragment potential (EFP) is employed to model the surrounding water molecules. The AIMD simulations for 7AI−H2O and 7AI−(H2O)2 clusters show an asynchronous hydrogen transfer at t ∼ 50 fs after the photoexcitation. While the ESHT mechanism for 7AI−H2O in water does not change appreciably compared with that in the gas phase, the AIMD simulations on 7AI−(H2O)2 in water solution exhibit two different mechanisms. Since the tautomer form is lower in energy compared to the normal form in the S1 state, 7AI and (H2O)n fragments separate from each other after the ESHT. With the use of the results of the AIMD trajectories, the minimum energy conical intersection point in the tautomer region has also been located. Disciplines Chemistry CommentsReprinted (adapted) ReceiVed: May 17, 2008; ReVised Manuscript ReceiVed: July 16, 2008 Ab initio molecular dynamics (AIMD) simulations for the excited-state hydrogen transfer (ESHT) reaction of 7-azaindole (7AI-(H 2 O) n ; n ) 1, 2) clusters in the gas phase and in water are presented. The effective fragment potential (EFP) is employed to model the surrounding water molecules. The AIMD simulations for 7AI-H 2 O and 7AI-(H 2 O) 2 clusters show an asynchronous hydrogen transfer at t ∼ 50 fs after the photoexcitation. While the ESHT mechanism for 7AI-H 2 O in water does not change appreciably compared with that in the gas phase, the AIMD simulations on 7AI-(H 2 O) 2 in water solution exhibit two different mechanisms. Since the tautomer form is lower in energy compared to the normal form in the S 1 state, 7AI and (H 2 O) n fragments separate from each other after the ESHT. With the use of the results of the AIMD trajectories, the minimum energy conical intersection point in the tautomer region has also been located.

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Theoretical characterization of intramolecular proton transfer in the ground and the lowest-lying triplet excited states of 1-amino-3-propenal: a methodological comparison

et al. 2000

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Several theoretical methods are employed to characterize the intramolecular proton transfer in the ground state and in the lowest-lying 3 nπ * and 3 ππ * excited states of 1-amino-3-propenal. The geometrical parameters, the relative energy of the two tautomeric forms, the energy barrier for the proton transfer, and the energy difference between the ground and the excited states predicted by the different methods are compared. It was found that: (1) the CASPT2 results are in good agreement with those obtained using the CCSD(T) method; (2) the CIS method and the CASSCF method with a medium-sized active space yield poor geometries and overestimate the adiabatic energy excitations and the energy barriers for the proton transfer; and (3) the B3LYP method provides good adiabatic excitation energies, although B3LYP energy barriers are

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Proton-transfer reaction dynamics

Cited by 549 publications

References 56 publications

Dynamics of excited-state proton transfer systems via time-resolved photoelectron spectroscopy

Dynamics of excited-state proton transfer systems via time-resolved photoelectron spectroscopy

Ab Initio QM/MM Molecular Dynamics Study on the Excited-State Hydrogen Transfer of 7-Azaindole in Water Solution

Theoretical characterization of intramolecular proton transfer in the ground and the lowest-lying triplet excited states of 1-amino-3-propenal: a methodological comparison

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