New heterocyclic systems to afford microsecond green-light isomerisable azo dyes and their use as fast molecular photochromic switches

García-Amorós, Jaume; Castro, M. Cidália R.; Coelho, Paulo J.; Raposo, M. Manuela M.; Velasco, Dolores

doi:10.1039/c3cc46736h

Cited by 63 publications

(48 citation statements)

References 25 publications

(23 reference statements)

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“…Optimization of the azobenzene photoswitch also inspired the investigation of azoheteroarenes. In general, in these compounds, one benzene ring of the azobenzene is substituted by a heterocycle that changes the electronic and steric properties of the molecules . A first promising example was reported by the group of Herges, who showed that azoindazoles presented complete E – Z isomerization, whereas Z – E isomerization, at only 55 %, was still insufficient.…”

Section: Introductionmentioning

confidence: 99%

Arylazopyrazole Photoswitches in Aqueous Solution: Substituent Effects, Photophysical Properties, and Host–Guest Chemistry

Stricker

Böckmann

Kirse

et al. 2018

Chemistry A European J

120

109

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Section: Introductionmentioning

confidence: 99%

Arylazopyrazole Photoswitches in Aqueous Solution: Substituent Effects, Photophysical Properties, and Host–Guest Chemistry

Stricker

Böckmann

Kirse

et al. 2018

Chemistry A European J

120

109

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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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“…The lifetime of the primary transient species, supposedly cis isomer, is 300-500 μs ( Table 2). It should be pointed out that the lifetime of this transient species for the compounds under study is close to the lowest limit of the lifetime for the cis isomer (70 μs), which was recently observed for hetarylazo dyes with ben zothiazole and pyrrole cycles [15]. The fast dark recov ery of the initial dyes results in low conversion degrees in the photostationary state, which was observed in the steady state photolysis.…”

Section: Methodsmentioning

confidence: 99%

Spectral and time-resolved properties of novel hetarylazo dyes containing hydrogenated quinolines and triazole moieties

et al. 2014

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The spectral characteristics of novel hetarylazo dyes containing triazole and hydrogenated quino line moieties and the spectral and time resolved parameters of photochemical processes occurring upon their photoexcitation were studied by stationary spectrophotometry and pulse photolysis. All compounds have an intense absorption maximum in the visible spectral range at 470-500 nm with ε = 17000-27000 L mol -1 cm -1 . Upon excitation with the visible light, reversible trans cis photoisomerization occurs, which is followed by thermal cis trans isomerization. The temporal parameters of the isomerization depend on the azo dye struc ture. The introduction of bulky substituents in the triazole and hydroquinoline moieties results in the increase in characteristic times of the thermal transformation of the generated transient species from milliseconds to seconds and in the partial irreversibility of the process.

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New heterocyclic systems to afford microsecond green-light isomerisable azo dyes and their use as fast molecular photochromic switches

Cited by 63 publications

References 25 publications

Arylazopyrazole Photoswitches in Aqueous Solution: Substituent Effects, Photophysical Properties, and Host–Guest Chemistry

Arylazopyrazole Photoswitches in Aqueous Solution: Substituent Effects, Photophysical Properties, and Host–Guest Chemistry

Photoisomerization of Arylazopyrazole Photoswitches: Stereospecific Excited‐State Relaxation

Spectral and time-resolved properties of novel hetarylazo dyes containing hydrogenated quinolines and triazole moieties

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