Azobenzene photoisomerization quantum yields in methanol redetermined

Ladányi, Vít; Dvořák, Pavel; Anshori, Jamaludin Al; Vetráková, Ľubica; Wirz, Jakob; Heger, Dominik

doi:10.1039/c7pp00315c

Cited by 59 publications

(64 citation statements)

References 28 publications

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“…This approximation offers the advantage that neither kinetic modeling nor numeric solving of differential equations is required. 54 Using ferrioxalate with online detection as a reference, we could reproduce quantum yields of several model systems. Our method utilizes cost-efficient low power LEDs for irradiation, and requires low amounts of sample, while allowing quick determination of quantum yields of photochemical reactions.…”

Section: Discussionmentioning

confidence: 99%

“…Very recently, the molar absorption coefficients and photo-isomerization quantum yields in methanol have been re-determined and reviewed. 53,54 Here we examine the conversion of a pre-irradiated solution containing predominantly Z-7 with a 400 nm LED in a kinetic approach. In the case of azobenzene, the change in absorbance dA/dt induced by the continuous irradiation I 0 is given by: 50…”

Section: Isomerization Of Azobenzene (7)mentioning

confidence: 99%

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A versatile method for the determination of photochemical quantum yields via online UV-Vis spectroscopy

Stadler

Eibel

Fast

et al. 2018

Photochem Photobiol Sci

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We have developed a simple method for determining the quantum yields of photo-induced reactions. Our setup features a fibre coupled UV-Vis spectrometer, LED irradiation sources, and a calibrated spectrophotometer for precise measurements of the LED photon flux. The initial slope in time-resolved absorbance profiles provides the quantum yield. We show the feasibility of our methodology for the kinetic analysis of photochemical reactions and quantum yield determination. The typical chemical actinometers, ferrioxalate and ortho-nitrobenzaldehyde, as well as riboflavin, a spiro-compound, phosphorus- and germanium-based photoinitiators for radical polymerizations and the frequently utilized photo-switch azobenzene serve as paradigms. The excellent agreement of our results with published data demonstrates the high potential of the proposed method as a convenient alternative to the time-consuming chemical actinometry.

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Section: Discussionmentioning

confidence: 99%

Section: Isomerization Of Azobenzene (7)mentioning

confidence: 99%

A versatile method for the determination of photochemical quantum yields via online UV-Vis spectroscopy

Stadler

Eibel

Fast

et al. 2018

Photochem Photobiol Sci

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“…Nevertheless, it was proposed that the slower S 1 relaxation pathways are reactive, while the fast ones are nonreactive . In this respect, the shift of the corresponding lifetime distribution in TphAB towards longer lifetimes (dominance of the reactive pathways) may potentially explain the much higher isomerization QY (44 %, see above) as compared to AB (≈10 %) …”

Section: Resultsmentioning

confidence: 99%

“…They also show a weakly allowed n→π* transition band (S 1 ) in the 400–450 nm range for both isomers. The photoisomerization quantum yield (QY) of ABs is excitation‐wavelength‐dependent: QY E( π→π* ) → Z ≈13 %, QY E( n→π* ) → Z ≈29 %, QY Z( π→π* ) → E ≈24–36 %, QY Z( n→π* ) → E ≈47–51 % …”

Section: Introductionmentioning

confidence: 99%

Thiophenylazobenzene: An Alternative Photoisomerization Controlled by Lone‐Pair⋅⋅⋅π Interaction

et al. 2019

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Azoheteroarene photoswitches have attracted attention due to their unique properties. We present the stationary photochromism and ultrafast photoisomerization mechanism of thiophenylazobenzene (TphAB). It demonstrates impressive fatigue resistance and photoisomerization efficiency, and shows favorably separated (E)‐ and (Z)‐isomer absorption bands, allowing for highly selective photoconversion. The (Z)‐isomer of TphAB adopts an unusual orthogonal geometry where the thiophenyl group is perfectly perpendicular to the phenyl group. This geometry is stabilized by a rare lone‐pair⋅⋅⋅π interaction between the S atom and the phenyl group. The photoisomerization of TphAB occurs on the sub‐ps to ps timescale and is governed by this interaction. Therefore, the adoption and disruption of the orthogonal geometry requires significant movement along the inversion reaction coordinates (CNN and NNC angles). Our results establish TphAB as an excellent photoswitch with versatile properties that expand the application possibilities of AB derivatives.

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“…Two different models will be utilized, for cross-and co-current, respectively. For crosscurrent, the model starts from a photochemical reaction that is reversible, with the starting equation being the following, based on [7,21,22] and building further on the work of Meir et al [6] :…”

Section: Actinometric Validationmentioning

confidence: 99%

Principles of coaxial illumination for photochemical reactions: Part 2. Model validation

Meir

Leblebici

Kuhn

et al. 2020

J Adv Manuf & Process

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This study reports the principles and model equations for co-and counter-current illumination, validated by experimental data. Current photochemical reactors which are homogeneously illuminated suffer from a light efficiency problem resulting in low light absorption and subsequent low productivity. Hence, the use of co-and counter-current illuminated reactors, implementing larger path lengths, without altering the reactor's geometry, is of interest. In this article, we report a simple model to determine the conversion obtained by co-and counter-current illumination techniques and compare against the current state-of-the-art. Via experimental validation, we report the use of co-and counter-current illumination to significantly boost the PSTY, a measure for photochemical reactor productivity, by a factor of 5 to 6 for same input concentration of reagent, solemnly by illuminating the reactor via co-and countercurrent (axially) instead of cross-current (radially). Furthermore, we report that simply increasing the reagent concentration, thus absorbance, has a large influence on productivity, thus PSTY, of the reactor. By assessing the reactor's performance parameters, derived by modeling, which are the initial absorbance value (A) and the quantum photon balance (ρϕ), the reactor's operating point can be determined and adapted to operate in a more productive and efficient regime.

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Azobenzene photoisomerization quantum yields in methanol redetermined

Cited by 59 publications

References 28 publications

A versatile method for the determination of photochemical quantum yields via online UV-Vis spectroscopy

A versatile method for the determination of photochemical quantum yields via online UV-Vis spectroscopy

Thiophenylazobenzene: An Alternative Photoisomerization Controlled by Lone‐Pair⋅⋅⋅π Interaction

Principles of coaxial illumination for photochemical reactions: Part 2. Model validation

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