The role of intersection topography in bond selectivity of<i>cis-trans</i>photoisomerization

Ben‐Nun, M.; Molnár, F.; Schulten, Klaus; Martı́nez, Todd J.

doi:10.1073/pnas.032658099

Cited by 148 publications

(163 citation statements)

References 37 publications

(43 reference statements)

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“…This demonstrates that high speed and coherence of the excited state wavepacket are not sufficient for a high quantum yield 40 . Topological details of the CI, possibly modified by the environment, may influence it as well 23,54 .…”

Section: Discussionmentioning

confidence: 99%

Coherent ultrafast torsional motion and isomerization of a biomimetic dipolar photoswitch

Briand

Bräm

Réhault

et al. 2010

Phys. Chem. Chem. Phys.

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: Discussionmentioning

confidence: 99%

Coherent ultrafast torsional motion and isomerization of a biomimetic dipolar photoswitch

Briand

Bräm

Réhault

et al. 2010

Phys. Chem. Chem. Phys.

103

163

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“…A few years ago, Kandori et al (40) proposed a model for the photodynamics of rhodopsin involving two different fluorescent species. The bond selectivity, which depends on the environment (protein vs. solvent) leading to the photoproducts (e.g., 13-cis and 11-cis), was attributed to the shape (topology) of the potential-energy surfaces (at S 0 and S 1 states) in the vicinity associated with the torsion of the involved double bonds in the isomerization (42). …”

Section: Femtochemistry In Solutionmentioning

confidence: 99%

“…1). We believe that the present work shines more light on the photodynamics of OII, and the results might be used for a better understanding of other systems undergoing isomerization reactions like retinal rhodopsin (38)(39)(40)(41)(42)(43)(44). trophotometers, respectively.…”

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confidence: 99%

Femtochemistry of orange II in solution and in chemical and biological nanocavities

Douhal

Sanz

Tormo

2005

Proc. Natl. Acad. Sci. U.S.A.

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In this work, we report on studies of the nature of the dynamics and hydrophobic binding in cyclodextrins and human serum albumin protein complexes with orange II. With femtosecond time resolution, we examined the proton-transfer and trans-cis isomerization reactions of the ligand in these nanocavities and in pure solvents. Because of confinement at the ground state, the orientational motion in the formed phototautomer is restricted, leading to a rich dynamics. Therefore, the emission lifetimes span a large window of tens to hundreds of picoseconds in the cavities. Possible H-bond interactions between the guest and cyclodextrin do not affect the caged dynamics. For the protein-ligand complexes, slow diffusional motion (Ϸ630 ps) observed in the anisotropy decay indicates that the binding structure is not completely rigid, and the embedded guest is not frozen with the hydrophobic pocket. The ultrafast isomerization and decays are explained in terms of coupling motions between N-N and C-N stretching modes of the formed tautomer. We discuss the role of confinement on the trans-cis isomerization with the cavities and its relationships to frequency and time domains of nanostructure emission.cyclodextrins ͉ protein ͉ H-bond ͉ twisting ͉ anisotropy F emtosecond (fs) studies of caged molecules in nanocavities provide direct information on the relationship between time and space domains of molecular relaxation (1). Therefore, simple and complex (in concept) molecular systems have been studied using cyclodextrins (CDs), proteins, micelles, pores, and zeolites as nanohosts, demonstrating the confinement effect of the hydrophobic nanocavities on the spectroscopy and dynamics of the guests (2-13). Relevant information on the ultrafast dynamics of caged wavepackets involving breaking͞making chemical bonds, and solvation has been acquired.Orange II (OII) (Fig. 1), also called acid orange 7, is a molecule that has O-H . . . N and NAN bonds and may show photoinduced intramolecular proton-transfer (IPT) and transcis isomerization reactions. It is widely used in the dyeing of textiles, food, and cosmetics and thus is found in the wastewaters of the related industries (14). It has been reported that it exists under azoenol (AZO) and ketohydrazone (HYZ) forms (Fig. 1) (15-20). In a water solution, for example, the H-atom within the O-H . . . N intramolecular H-bond is shifted to the nitrogen site, making HYZ structure the most stable one (Ϸ95%) (20). In DMSO, the HYZ population decreases to 70%, and in solid state it becomes the only populated structure (20). Recent x-ray studies of phenyl substituted 1-(arylazo)-2-naphthols showed that this kind of molecules displaying HYZ-AZO tautomerism can form intramolecular resonance-assisted H-bonds from pure N-H . . . O to pure N . . . H-O structures, depending on the phenyl derivative (21, 22). Furthermore, a recent photophysical study of similar molecules in solution has shown the occurrence of a photoinduced proton-transfer reaction in AZO to give HYZ structure with a very low emission qu...

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“…The basic model had a lot in common with much of our other analytic modeling work (e.g., 90): (a) an electronic structure described by two valence bond states-with the attractive feature of being an extension of the two-electron, two-orbital model constructed years before by my Boulder colleague Josef Michl and his coworkers (124)-and (b) a few-coordinate description-here of the PSB torsion for the isomerization per se, an intramolecular bond length alteration coordinate to deal with the single-double bond switching involved, and a solvent coordinate, with the coordinate allowing for nonequilibrium solvation aspects related to the Franck-Condon electronic transition, the isomerization, and the passage through the CI. Further key modeling aspects were informed by prior PSB work of Mike Todd Martínez (128,129), and their coworkers. The major results of our analysis for the ground and excited state free energy surfaces and inertial motion on them were insights on the important role that the solvent could play.…”

Section: Conical Intersection Dynamicsmentioning

confidence: 99%

Molecules in Motion: Chemical Reaction and Allied Dynamics in Solution and Elsewhere

Hynes

2015

Annu. Rev. Phys. Chem.

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After my acceptance of the kind invitation from Todd Martínez and Mark Johnson, Co-Editors of this journal, to write this article, I had to decide just how to actually do this, given the existence of a fairly personal and extended autobiographical account of recent vintage detailing my youth, education, and assorted experiences and activities at the University of Colorado, Boulder, and later also at Ecole Normale Supérieure in Paris (1). In the end, I settled on a differently styled recounting of the adventures with my students, postdocs, collaborators, and colleagues in trying to unravel, comprehend, describe, and occasionally even predict the manifestations and consequences of the myriad assortment of molecular dances that contribute to and govern the rates and mechanisms of chemical reactions in solution (and elsewhere TRANSLATIONAL, ROTATIONAL, AND SOLVATION DYNAMICS IN SOLUTIONThis is basically where it all began for me. Beyond their fundamental interest, these three types of dynamics (translational, rotational, and solvation) can be important for chemical reactions in assorted regimes, although admittedly this is perhaps not always so obvious: Translation is relevant for diffusion-controlled and -influenced reactions, water rotation is important for proton transfers (PTs), for example, and solvation dynamics can have a significant effect on any reaction involving the redistribution or rearrangement of charges. I give only brief commentaries on our work at the University of Colorado, Boulder, on these types of dynamics in the 1970s and 1980s and end with more recent aspects carried out at Ecole Normal Supérieure (ENS).In the 1970s, it was thought by not a few that macroscopic continuum hydrodynamics-as reflected in, e.g., Stokes' friction laws for translation and rotation, the Stokes-Einstein equation for translational diffusion, and the Debye-Stokes-Einstein relation for rotational or reorientational diffusion-could actually apply in detail, and even quantitatively, at a molecular level. I myself have used (and continue to use) continuum hydrodynamic and dielectric models to provide concepts, perspectives, and guides for experiment. Clearly, I like such models greatly, but I just could not accept going this far. Together with Mike Weinberg and Ray Kapral (2-4), we addressed the issue with what we called a microscopic boundary layer approach, combining a molecular collisional picture for the immediate solvent neighborhood of a rotating or translating solute molecule with a hydrodynamic description of the remaining, outer solvent. We showed that for both rotational and translational friction (and thus for diffusion), the molecular aspects were indeed dominant. Although hydrodynamic influences could also enter, they only became the dominant story when the solute was far larger than the solvent molecules. We also found that the supposed agreement of assorted simulations and experiments with the hydrodynamic view disappeared upon suitable scrutiny. Solvation DynamicsThis flavor of dynamics came into it...

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The role of intersection topography in bond selectivity ofcis-transphotoisomerization

Cited by 148 publications

References 37 publications

Coherent ultrafast torsional motion and isomerization of a biomimetic dipolar photoswitch

Coherent ultrafast torsional motion and isomerization of a biomimetic dipolar photoswitch

Femtochemistry of orange II in solution and in chemical and biological nanocavities

Molecules in Motion: Chemical Reaction and Allied Dynamics in Solution and Elsewhere

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