The Relation between the Absorption Spectra and the Chemical Constitution of Dyes. XXV. Phototropism and cis-trans Isomerism in Aromatic Azo Compounds<sup>1</sup>

Brode, Wallace R.; Gould, John; Wyman, George M.

doi:10.1021/ja01138a059

Cited by 162 publications

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“…[41] Since then a lot of studies have been done dealing with the particular photochromic and isomerization properties of azo compounds. Wyman has covered the literature up to 1955 [42] [43] and Ross and Blanc up to 1970. [44] The spectroscopy was reviewed by Rau in 1973 [45]- [48] and the chemistry and characteristics of azo compounds were studied extensively by…”

Section: Photophysical Properties Of Azo Compoundsmentioning

confidence: 99%

“…[3][4] [49][51] [69] As described above the photo induced reversible trans cis isomerization of azobenzene derivatives provides structural change to a considerable extent. [43][70]- [73] The azobenzene motif is thus an ideal building block to integrate light induced conformational changes in molecular structures. [16][74]- [76] A certain drawback of the structural change of such molecular structures was the relatively short life time of the thermodynamically less favored cis isomer.…”

Section: Macrocyclic Azo Compoundsmentioning

confidence: 99%

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Shape‐Switchable Azo‐Macrocycles

et al. 2009

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The synthesis of four shape‐switchable macrocycles comprising different peripheral substituents is described. The macrocycles 1–4 consist of m‐terphenyl semicircles interlinked by two azo joints. These macrocycles were assembled from nitro‐functionalized m‐terphenyl moieties through reductive dimerization. The semicircles were assembled through Suzuki cross‐coupling reactions. The molecular weights of the macrocycles were determined by vapour pressure osmometry, because mass spectrometry failed in the cases of 2 and 3. The E → Z photoisomerization reactions were analysed by UV/Vis spectroscopy complemented by 1H NMR studies. A very slow thermal back‐reaction indicated considerable stabilization of the Z isomer. The reduced efficiency of the thermal back‐reaction probably arises from the reduced degree of freedom due to the mechanical interlinking of the two azo groups. The photostationary state consisted of all‐Z (85 %) and all‐E isomers (15 %). The E → Z transformation induced by irradiation displayed simple exponential kinetics, which indicates pairwise switching of the two azo groups in a macrocycle, at least on the timescale under investigation. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

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Section: Photophysical Properties Of Azo Compoundsmentioning

confidence: 99%

Section: Macrocyclic Azo Compoundsmentioning

confidence: 99%

Shape‐Switchable Azo‐Macrocycles

et al. 2009

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“…Effectively complete bypass of the thermal process occurs at light intensity sufficiently low to produce no observable effects of average heating. The success of azobenzenes in converting photon energy to effective local fluidization can be attributed to their distinctive photo-induced change in molecular shape 16,17 , combined with, importantly, relatively slow (B10 ps) dynamics 18 of the resulting energy transfer to their local environment.…”

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confidence: 99%

Athermal photofluidization of glasses

et al. 2013

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Azobenzene and its derivatives are among the most important organic photonic materials, with their photo-induced trans-cis isomerization leading to applications ranging from holographic data storage and photoalignment to photoactuation and nanorobotics. A key element and enduring mystery in the photophysics of azobenzenes, central to all such applications, is athermal photofluidization: illumination that produces only a sub-Kelvin increase in average temperature can reduce, by many orders of magnitude, the viscosity of an organic glassy host at temperatures more than 100 K below its thermal glass transition. Here we analyse the relaxation dynamics of a dense monolayer glass of azobenzene-based molecules to obtain a measurement of the transient local effective temperature at which a photo-isomerizing molecule attacks its orientationally confining barriers. This high temperature (T loc B800 K) leads directly to photofluidization, as each absorbed photon generates an event in which a local glass transition temperature is exceeded, enabling collective confining barriers to be attacked with near 100% quantum efficiency.

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“…Experimentally, in the absorption spectra of the host-guest polymer films it was possible to obtain only the absorption band of trans-isomer. The values of absorption bands for cis-isomer are usually calculated [1,6]. This means that in the case of cisisomer we can use approximate values of the absorption bands.…”

Section: Resultsmentioning

confidence: 99%

Optically Induced Surface Relief Gratings in Polymer Films Doped With Sulphonyl Group Containing Azobenzene

Laizane¹,

Gustina²,

Kundziņš³

et al. 2010

Latvian Journal of Physics and Technical Sciences

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In holography, more attractive have become azobenzene compounds doped in a polymer matrix (host-guest polymer film) or chemically attached to the polymer. Azobenzene molecules exhibit reversible photoisomerization between trans-and cisisomers which can form a surface relief grating in the films. The authors investigate the holographic recording and formation of surface relief gratings in a host-guest polymer film with two original azobenzene compounds. Holographic recording with 325 nm laser light was performed in host-guest polymer films with the host being polymethylmetacrylate (PMMA) and the guest -15 wt% azobenzene molecules (A-45 or A-48). In both cases an increase in the diffraction efficiency at the beginning of the process could be related to the trans-cis-photoisomerization, while the second increase − to the formation of surface relief gratings. The systems with A-45 molecules reach a diffraction efficiency of 0.7%, and with A-48 molecules − of 0.24%. Also, the depth of surface relief gratings is greater in the films with A-45 (35 to 45 nm) than in those with A-48 (4 to 6 nm) molecules.

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The Relation between the Absorption Spectra and the Chemical Constitution of Dyes. XXV. Phototropism and cis-trans Isomerism in Aromatic Azo Compounds¹

Cited by 162 publications

References 0 publications

Shape‐Switchable Azo‐Macrocycles

Shape‐Switchable Azo‐Macrocycles

Athermal photofluidization of glasses

Optically Induced Surface Relief Gratings in Polymer Films Doped With Sulphonyl Group Containing Azobenzene

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The Relation between the Absorption Spectra and the Chemical Constitution of Dyes. XXV. Phototropism and cis-trans Isomerism in Aromatic Azo Compounds1

Cited by 162 publications

References 0 publications

Shape‐Switchable Azo‐Macrocycles

Shape‐Switchable Azo‐Macrocycles

Athermal photofluidization of glasses

Optically Induced Surface Relief Gratings in Polymer Films Doped With Sulphonyl Group Containing Azobenzene

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Product

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The Relation between the Absorption Spectra and the Chemical Constitution of Dyes. XXV. Phototropism and cis-trans Isomerism in Aromatic Azo Compounds¹