Quantum Chemical Modeling and Preparation of a Biomimetic Photochemical Switch

Lumento, Flavio; Zanirato, Vinicio; Fusi, Stefania; Busi, Elena; Latterini, Loredana; Elisei, Fausto; Sinicropi, Adalgisa; Andruniów, Tadeusz; Ferré, Nicolas; Basosi, Riccardo; Olivucci, Massimo

doi:10.1002/anie.200602915

Cited by 67 publications

(79 citation statements)

References 38 publications

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“…4B), which most likely is a C=C stretch. This observation supports the existence of a π-π* transition with bond order change, which weakens the isomerizing double bond 26,27 , as directly evidenced by the mid-IR bleach band. Fluorescence, stimulated emission as well as ESA 1 and 2 bands are then observed to occur within the IRF and to decay with times of ~0.15 ps (~90 % amplitude) and ~1 ps (~10%).…”

Section: Discussionsupporting

confidence: 80%

“…This yields the "true" absorption spectra of photo-excited ZW-NAIP molecules from the moment of excitation up to the completion of the photoreaction; these spectra are shown in The complete disappearance of the 1570 cm -1 band upon photoexcitation is consistent with ab initio minimum energy path calculations, which predict loss of C=C double bond character in the S 1 excited state to occur prior to torsional motion about the thus weakened C1'-C4 bond 27,28 . Its sub-picosecond reappearance is thus interpreted as a signature for the return of photo-excited molecules into the electronic ground state, as previously observed for MeO-NAIP 26,27 . At delays longer than 2 ps the essentially constant integrated signal in Fig.…”

Section: Results and Analysissupporting

confidence: 69%

“…It is a Z/E photo-switch, bearing a record isomerisation speed of 200 fs 2 and quantum yield of more than 60% 25 . Quantitative computations of the excited state of PSBR in rhodopsin 21 have triggered the design of a new family of photoswitches, the N-alkylated indanylidene pyrroline Schiff bases (NAIP) 26 , which mimic the photo-induced charge translocation and structural dynamics of the natural pigment. The biomimetic photoswitches have a single isomerizing bond, present one low-lying excited state, dissolve well in water and in other polar solvents and are small enough to be entirely manageable by state-of-the-art quantum chemistry methods.…”

Section: Photoisomerization Is Currently Described As a Process Involmentioning

confidence: 99%

“…The biomimetic photoswitches have a single isomerizing bond, present one low-lying excited state, dissolve well in water and in other polar solvents and are small enough to be entirely manageable by state-of-the-art quantum chemistry methods. A methoxylated form of NAIP (MeO-NAIP) has been studied by quantum mechanics/molecular mechanics (QM/MM) computations, wavepacket dynamics simulations, and ultrafast spectroscopy, showing that, in methanol (MeOH), MeO-NAIP displays excited state properties similar to those of the 11-cis PSBR embedded in rhodopsin 26,27 . In particular, upon light excitation a barrierless excited state profile drives the molecular system through a CI to the isomer within 0.3 ps.…”

Section: Photoisomerization Is Currently Described As a Process Involmentioning

confidence: 99%

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Coherent ultrafast torsional motion and isomerization of a biomimetic dipolar photoswitch

Briand

Bräm

Réhault

et al. 2010

Phys. Chem. Chem. Phys.

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103

163

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(<250 words). Femtosecond fluorescence up-conversion, UV-Vis and IRtransient absorption spectroscopy are used to study the photo-isomerization dynamics of a new type of zwitterionic photoswitch based on a N-alkylated idanylidene pyrroline Schiff base framework (ZW-NAIP). The system is biomimetic, as it mimics the photophysics of retinal, in coupling excited state charge translocation and isomerisation. While the fluorescence lifetime is 140 fs, excited state absorption persists over 230 fs in form of a vibrational wavepacket according to twisting of the isomerising double bond. After a short "dark" time window in the UV-visible spectra, which we associate to the passage through a conical intersection (CI), the wavepacket appears on the ground state potential energy surface, as evidenced by the transient mid-IR data. This allows for a precise timing of the photoreaction all the way from the initial Franck-Condon region, through the CI and into both ground state isomers, until incoherent vibrational relaxation dominates the dynamics. The photo-reaction dynamics remarkably follow those observed for retinal in rhodopsin, with the additional benefit that in ZW-NAIP the conformational change reverses the zwitterion dipole moment direction. Last, the pronounced low-frequency coherences make these molecules ideal systems for 3 investigating wavepacket dynamics in the vicinity of a CI and for coherent control experiments.4

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Section: Discussionsupporting

confidence: 80%

Section: Results and Analysissupporting

confidence: 69%

Section: Photoisomerization Is Currently Described As a Process Involmentioning

confidence: 99%

Section: Photoisomerization Is Currently Described As a Process Involmentioning

confidence: 99%

See 2 more Smart Citations

Coherent ultrafast torsional motion and isomerization of a biomimetic dipolar photoswitch

Briand

Bräm

Réhault

et al. 2010

Phys. Chem. Chem. Phys.

Self Cite

103

163

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“…Clarifying the mechanism behind this ultrafast and efficient reaction is crucial for a general understanding of efficient and fast biological molecular photo-switches, and for exploiting these properties in artificial/bio-mimetic systems. 4 This photoreaction has been studied in the past both in vacuo [5][6][7] and in the protein binding pocket. [8][9][10][11][12] All calculations support an ultrafast dynamics through a conical intersection (CI), which directly connects the excited and ground state potentials of the retinal chromophore.…”

mentioning

confidence: 99%

Product formation in rhodopsin by fast hydrogen motions

Weingart

Altoè

Stenta

et al. 2011

Phys. Chem. Chem. Phys.

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The photochemical cis-trans isomerization of retinal in rhodopsin is investigated by structure sampling and excited state QM/MM trajectories with surface hopping. The calculations uncover the motions responsible for photoproduct formation and elucidate the reasons behind the efficient photoisomerization in the primary event of visual transduction.Visual perception is one of the most fascinating photochemical processes devised by nature. The rhodopsin protein (Rh), through photoinduced molecular deformations, converts with remarkable efficiency the energy of a single photon into chemical energy, eventually leading to a nerve impulse and vision. 1,2 Its primary event involves an ultrafast (200 fs) and efficient (0.65 quantum yield) cis-trans isomerisation of the 11-cis retinal protonated Schiff base (PSB) chromophore. In solvent, the quantum yield is more than three times smaller 3 and the photoisomerization is slower by a factor of 10. Clarifying the mechanism behind this ultrafast and efficient reaction is crucial for a general understanding of efficient and fast biological molecular photo-switches, and for exploiting these properties in artificial/bio-mimetic systems. 4 This photoreaction has been studied in the past both in vacuo 5-7 and in the protein binding pocket. [8][9][10][11][12] All calculations support an ultrafast dynamics through a conical intersection (CI), which directly connects the excited and ground state potentials of the retinal chromophore.Very recent hybrid QM(CASSCF)/MM simulations in Rh 13 have produced experimentally accurate transient sub-20 fs spectroscopies of the CI dynamics and primary visual event (i.e., the 200 fs photorhodopsin formation) that are supportive of a space saving photoisomerization mechanism reminiscent of Warshel's bicycle pedal model. 14 These findings alone, however, can not explain why the photoisomerization in rhodopsin is so uniquely efficient. The remarkable success of this process must be connected with characteristic geometrical changes which assure that at the reactive point (the CI) the wave packet is directed mainly toward the photoproduct side of the potential energy surface, i.e. the all-trans retinal. Candidates for these motions are the internal coordinates which change the dihedrals of the isomerizing double bond, i.e. the C11QC12 carbon skeletal twisting, but also torsion of the C11 and C12 hydrogens, which is related to the hydrogen out-of-plane (HOOP) mode at this bond. Participation of the HOOP mode has been supposed first by Mathies et al., based on the analysis of Raman spectra. 15 A direct connection between the quantum yield and the HOOP motion has been drawn in earlier studies of pre-twisted retinal models in vacuo, where an even higher quantum yield (0.75) has been reported than in rhodopsin. 16 By employing an extended sample of hybrid QM(CASSCF)/ MM trajectories at physiological conditions (50 trajectories, 300 K), here we analyse the motions of the rhodopsin photoreaction leading to the product (11-trans) and educt (11-cis) sides of the ...

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Bistable and Multistable Systems

Balzani

Venturi

2008

Molecular Devices and Machines

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Quantum Chemical Modeling and Preparation of a Biomimetic Photochemical Switch

Cited by 67 publications

References 38 publications

Coherent ultrafast torsional motion and isomerization of a biomimetic dipolar photoswitch

Coherent ultrafast torsional motion and isomerization of a biomimetic dipolar photoswitch

Product formation in rhodopsin by fast hydrogen motions

Bistable and Multistable Systems

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