Direct Observation of Nuclear Motion during Ultrafast Intramolecular Proton Transfer

Lochbrunner, Stefan; and, Christian Schriever; Riedle, Eberhard

doi:10.1002/9783527611546.ch11

Cited by 4 publications

(4 citation statements)

References 76 publications

(168 reference statements)

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“…We turn now to the initial phase of the photoinduced dynamics of HQBT . The DAS of the 200 fs component indicates that the SE declines in the near-UV region and increases above 450 nm which represents a pronounced red shift of the emission which is indicative of ESIPT . In HPBT , it was found that the ESIPT itself takes 35 fs and is followed by a red shift of the emission within about 250 fs due to internal vibrational redistribution (IVR) .…”

Section: Resultsmentioning

confidence: 99%

“…The DAS of the 200 fs component indicates that the SE declines in the near-UV region and increases above 450 nm which represents a pronounced red shift of the emission which is indicative of ESIPT. 76 In HPBT, it was found that the ESIPT itself takes 35 fs and is followed by a red shift of the emission within about 250 fs due to internal vibrational redistribution (IVR). 54 In the present case, the time resolution of about 100 fs does not allow to disentangle these two processes.…”

Section: ■ Introductionmentioning

confidence: 99%

“…For other ESIPT compounds, the formation of a twisted conformer similar to KK was also postulated. 75,76 However, since they lack an accessible proton acceptor, no subsequent ground-state PT and formation of a K analogue occurs, but a fast back-isomerization inhibiting the capability to act as a switch occurs.…”

Section: ■ Introductionmentioning

confidence: 99%

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Reversible Switching Based on Truly Intramolecular Long-Range Proton Transfer─Turning the Theoretical Concept into Experimental Reality

Rehhagen,

Argüello Cordero,

Kamounah

et al. 2024

J. Am. Chem. Soc.

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Herein, we demonstrate a working prototype of a conjugated proton crane, a reversible tautomeric switching molecule in which truly intramolecular long-range proton transfer occurs in solution at room temperature. The system consists of a benzothiazole rotor attached to a 7-hydroxy quinoline stator. According to the experimental and theoretical results, the OH proton is delivered under irradiation to the quinolyl nitrogen atom through a series of consecutive proton transfer and twisting steps. The use of a rigid rotor prevents undesired side processes that decrease the switching performance in previously described proton cranes and provides an unprecedented switching efficiency and fatigue resistance. The newly designed system confirms the theoretical concept for the application of proton transfer-initiated intramolecular twisting as the switching mechanism, developed more than 10 years ago, and provides unique insights for the further development of tautomeric molecular switches and motors, molecular logic gates, and new molecular-level energy storage systems.

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Section: Resultsmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

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Reversible Switching Based on Truly Intramolecular Long-Range Proton Transfer─Turning the Theoretical Concept into Experimental Reality

Rehhagen,

Argüello Cordero,

Kamounah

et al. 2024

J. Am. Chem. Soc.

Self Cite

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“…Shifts in electron density after electronic excitation lead to significant enhancement in the acidity of the proton-donating group and in the basicity of the acceptor group thus facilitating the intramolecular proton transfer. In many cases this transfer is characterized by the absence of any energy barrier showing basically a vibrational relaxation mechanism in the excited state where the proton transfer proceeds as a ballistic wave packet motion on a time scale of less than 50 fs and involves skeletal deformations that modulate the donor−acceptor distance. ,,, From the multitude of examples, 2-(2′-hydroxyphenyl)benzothiazole (HBT), 10-hydroxybenzo[h]quinoline (HBQ), and 2-(2′-hydroxyphenyl)benzotriazole (TIN-H) relevant for the present investigations should be mentioned here.…”

Section: Introductionmentioning

confidence: 99%

Excited-State Diproton Transfer in [2,2′-Bipyridyl]-3,3′-diol: the Mechanism Is Sequential, Not Concerted

et al. 2009

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The excited-state mono- and diproton transfer has been investigated in the S(1) state of [2,2'-bipyridyl]-3,3'-diol using the quantum mechanical resolution-of-identity second-order approximate coupled-cluster (RI-CC2) and time-dependent density functional theory (TDDFT) methods. Static investigation of stationary points and scans of the pi pi* and n pi* energy surfaces have been performed. These calculations show that the concerted diproton transfer in S(1) proceeds along a ridge thus making this process highly unlikely since it will stabilize toward the unsymmetrical monoproton transfer. A small energy barrier of about 0.11 eV (RI-CC2 result) between the mono- and diketo structures is obtained allowing rapid continuation of the proton transfer to the diketo form. On-the-fly dynamics simulations performed at the RI-CC2 level confirm this picture. The first proton transfer step is so fast (7 fs) that it probably cannot be resolved by experimental techniques. Important participation of the n pi* state is predicted. The present results shed a completely new light on the interpretation of the experimental results. The simulations clearly show that what has been experimentally determined as concerted transfer is in fact a combination of two sequential proton transfers separated by a small delay below the present experimental resolution. Concerning the second step of the sequential proton transfer the dynamics calculations indicate the existence of a highly dynamic system. Both the forward and reverse reactions of a monoketo/diketo equilibrium were found within the 300 fs period of the simulation. Environmental effects will certainly lead to a substantial cooling of the initially hot molecule and a concomitant decrease in the monoketo/diketo conversion rates, which will result in the experimentally observed overall time scale of 10 ps for the second proton transfer step.

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Femtosecond Pump–Probe Spectroscopy of Photoinduced Tautomerism

Lochbrunner

2013

Tautomerism

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Direct Observation of Nuclear Motion during Ultrafast Intramolecular Proton Transfer

Cited by 4 publications

References 76 publications

Reversible Switching Based on Truly Intramolecular Long-Range Proton Transfer─Turning the Theoretical Concept into Experimental Reality

Reversible Switching Based on Truly Intramolecular Long-Range Proton Transfer─Turning the Theoretical Concept into Experimental Reality

Excited-State Diproton Transfer in [2,2′-Bipyridyl]-3,3′-diol: the Mechanism Is Sequential, Not Concerted

Femtosecond Pump–Probe Spectroscopy of Photoinduced Tautomerism

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