Computational Photochemistry of the Azobenzene Scaffold of Sudan I and Orange II Dyes: Excited‐State Proton Transfer and Deactivation via Conical Intersections

Guan, Pei-Jie; Cui, Ganglong; Qiu, Fang

doi:10.1002/cphc.201402743

Cited by 31 publications

(34 citation statements)

References 81 publications

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“…[38,39] Figure 3 shows the results of a representative trajectory, which takes 188.5 fs to reach the CI point, at which the potential energy surfaces of S 1 and S 0 state almost cross and the S 1 -S 0 state energy difference is merely 0.14 eV (The structural evolution during the simulation of this trajectory can be found in Movie S1.). [41] As shown in Figure 4b, by performing structural optimization at the CASSCF(10,10)/6-21G level of theory, a CI geometry with S 1 -S 0 transition energy of 0.002 eV and with essentially identical structural features to the TD-DFT result was found (see Table S3 for atom coordinates of the CI structure). The breaking of one CÀ O bond is the most prominent change of the molecular structure and accounts for the CI formation.…”

Section: Resultsmentioning

confidence: 72%

“…[24] As such, we have used the CASSCF method to make further confirmation (we also performed a rigid scan to investigate potential energy profiles of the S 0 and S 1 states of the graphene epoxide nanostructure as a function of OÀ C-C angles at the epoxide moiety, which provides further understanding on the nonradiative decay via CI; see Figure S1). [41] As shown in Figure 4b, by performing structural optimization at the CASSCF(10,10)/6-21G level of theory, a CI geometry with S 1 -S 0 transition energy of 0.002 eV and with essentially identical structural features to the TD-DFT result was found (see Table S3 for atom coordinates of the CI structure). [26,32] The consistent result found between the TD-DFT and CASSCF calculations further shows the feasibility of using the FSSH method based on TD-DFT to conduct excited-state dynamics studies.…”

Section: Resultsmentioning

confidence: 72%

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Nonradiative Excited‐State Decay via Conical Intersection in Graphene Nanostructures

et al. 2019

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Chemical groups are known to tune the luminescent efficiencies of graphene-related nanomaterials, but some species, including the epoxide group (À COCÀ ), are suspected to act as emissionquenching sites. Herein, by performing nonadiabatic excitedstate dynamics simulations, we reveal a fast (within 300 fs) nonradiative excited-state decay of a graphene epoxide nanostructure from the lowest excited singlet (S 1 ) state to the ground (S 0 ) state via a conical intersection (CI), at which the energy difference between the S 1 and S 0 states is approximately zero. This CI is induced after breaking one CÀ O bond at the À COCÀ moiety during excited-state structural relaxation. This study ascertains the role of epoxide groups in inducing the nonradiative recombination of the excited electron-hole, providing important insights into the CI-promoted nonradiative deexcitations and the luminescence tuning of relevant materials. In addition, it shows the feasibility of utilizing nonadiabatic excited-state dynamics simulations to investigate the photophysical processes of the excited states of graphene nanomaterials. Computational DetailsThe ground-and excited-state properties were studied by density functional theory (DFT) and time-dependent DFT (TD-DFT), respectively, as implemented by the Gaussian 09[a] S.

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Section: Resultsmentioning

confidence: 72%

Section: Resultsmentioning

confidence: 72%

Nonradiative Excited‐State Decay via Conical Intersection in Graphene Nanostructures

et al. 2019

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“…At S1-N-MIN, the intramolecular N4ÀH5···N15 hydrogen bond length is shortened remarkably compared with that in S0-N-MIN, which indicates that the excited-state hydrogenbondingi nteraction is enhanced due to the p!p*e lectronic transition, as already seen in several similars ystems studied recently. [67,68] This shortening benefits the following intramolecular excited-state protont ransfer (see below). Other visible structuralc hanges are elongation of the C9ÀC14a nd C3ÀN4 bonds and shortening of the C3ÀC9 and C14ÀN15 bonds.…”

Section: S 1 Minima and Esiptmentioning

confidence: 99%

“…Finally,w em ust stress that this type of S 1 ESIPT-induced equilibrium is rarely reported computationally;i nstead, in most previous computational studies the S 1 excited-state intramolecular proton transfer is usually barrierless and also corresponds to am uch more exothermic process. [11,22,[67][68][69][70]…”

Section: S 1 Minima and Esiptmentioning

confidence: 99%

Excited‐State Intramolecular Proton Transfer in a Blue Fluorescence Chromophore Induces Dual Emission

Guo

et al. 2016

ChemPhysChem

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Compared with green fluorescence protein (GFP) chromophores, the recently synthesized blue fluorescence protein (BFP) chromophore variant presents intriguing photochemical properties, for example, dual fluorescence emission, enhanced fluorescence quantum yield, and ultra-slow excited-state intramolecular proton transfer (ESIPT; J. Phys. Chem. Lett., 2014, 5, 92); however, its photochemical mechanism is still elusive. Herein we have employed the CASSCF and CASPT2 methods to study the mechanistic photochemistry of a truncated BFP chromophore variant in the S0 and S1 states. Based on the optimized minima, conical intersections, and minimum-energy paths (ESIPT, photoisomerization, and deactivation), we have found that the system has two competitive S1 relaxation pathways from the Franck-Condon point of the BFP chromophore variant. One is the ESIPT path to generate an S1 tautomer that exhibits a large Stokes shift in experiments. The generated S1 tautomer can further evolve toward the nearby S1 /S0 conical intersection and then jumps down to the S0 state. The other is the photoisomerization path along the rotation of the central double bond. Along this path, the S1 system runs into an S1 /S0 conical intersection region and eventually hops to the S0 state. The two energetically allowed S1 excited-state deactivation pathways are responsible for the in-part loss of fluorescence quantum yield. The considerable S1 ESIPT barrier and the sizable barriers that separate the S1 tautomers from the S1 /S0 conical intersections make these two tautomers establish a kinetic equilibrium in the S1 state, which thus results in dual fluorescence emission.

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“…To improve overall performance,many groups have explored the properties of azobenzene variants by altering the substituents on the aromatic rings,f or example,i nb ridged and orthohydroxy azobenzenes. [23][24][25][26][27][28][29][30] Recently,n ovel classes of azoheterocycle photoswitches were reported, [31][32][33][34][35][36] especially arylazopyrazoles,w hich provide quantitative photoswitching and high thermal stability (ca. 1000 days).…”

mentioning

confidence: 99%

Photoisomerization of Arylazopyrazole Photoswitches: Stereospecific Excited‐State Relaxation

Wang

Cui

et al. 2016

Angew Chem Int Ed

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Electronic structure calculations and nonadiabatic dynamics simulations (more than 2000 trajectories) are used to explore the Z-E photoisomerization mechanism and excitedstate decayd ynamics of two arylazopyrazole photoswitches. Tw oc hiral S 1 /S 0 conical intersections with associated enantiomeric S 1 relaxation paths that are barrierless and efficient (timescale of ca. 50 fs) were found. Forthe parent arylazopyrazole( Z8) both paths contribute evenly to the S 1 excited-state decay, whereas for the dimethyl derivative (Z11) each of the two chiral cis minima decays almost exclusively through one specific enantiomeric S 1 relaxation path. To our knowledge,the Z11 arylazopyrazole is thus the first example for nearly stereospecific unidirectional excited-state relaxation.Photoswitchable compounds have many potential applications ranging from photopharmacology through optochemical genetics to data storage. [1,2] Azobenzenes are among the most studied photoswitchable compounds,s ince they are easily synthesized and highly stable. [3,4] Their high extinction coefficients and isomerization quantum yields enable repeated photoswitching with low-intensity light. Photoinduced isomerization leads to ar emarkable change of the shape and length of these azobenzenes,w hich has been exploited, for example,intuning the folding and unfolding of peptides and proteins. [5][6][7][8] Many azobenzenes have been explored experimentally and computationally in the past decade, [9][10][11][12][13][14][15][16][17][18][19][20][21][22] but there remain af ew drawbacks that limit their broad application. These include incomplete photoswitching because of overlapping absorbance of the two isomers and fast thermal rearrangement of the cis isomer (Z)b ack to the trans isomer (E). To improve overall performance,many groups have explored the properties of azobenzene variants by altering the substituents on the aromatic rings,f or example,i nb ridged and orthohydroxy azobenzenes. [23][24][25][26][27][28][29][30] Recently,n ovel classes of azoheterocycle photoswitches were reported, [31][32][33][34][35][36] especially arylazopyrazoles,w hich provide quantitative photoswitching and high thermal stability (ca. 1000 days). [35,36] Thea bsorption band maxima of the Eand Z-isomers of arylazopyrazoles are found to be well separated, which enables quantitative two-way photoswitching.[35] Furthermore,t he substitution on the heterocyclic ring offers photophysical and photochemical properties that cannot be accessed with azobenzenes.H owever,t he photoinduced isomerization mechanism and the dynamical behavior of these arylazopyrazoles are still unexplored at the atomistic level. Obvious questions that remain are: 1) Whether azobenzenes and arylazopyrazoles share similar photophysical and photochemical mechanisms and 2) whether they show analogous dynamical behavior (lifetimes,c onical intersections,p ath selectivities). Ad etailed mechanistic understanding will be helpful to further improve their performance through rational design. Motivated by ...

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Computational Photochemistry of the Azobenzene Scaffold of Sudan I and Orange II Dyes: Excited‐State Proton Transfer and Deactivation via Conical Intersections

Cited by 31 publications

References 81 publications

Nonradiative Excited‐State Decay via Conical Intersection in Graphene Nanostructures

Nonradiative Excited‐State Decay via Conical Intersection in Graphene Nanostructures

Excited‐State Intramolecular Proton Transfer in a Blue Fluorescence Chromophore Induces Dual Emission

Photoisomerization of Arylazopyrazole Photoswitches: Stereospecific Excited‐State Relaxation

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