- Remote-control photocycloreversion of dithienylethene driven by strong push-pull azo chromophores
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In this communication, a novel photochromic molecular switch DTE-2(Azo-CN) containing both dithienylethene and push-pull azo chromophores was synthesized. The push-pull azo chromophores can significantly accelerate the ring opening of the C-C bond of DTE closed isomer when irradiated with light far away from the maximum absorption band of the DTE closed isomer.
- He, Yaning,Zhu, Yan,Chen, Zhen,He, Wei,Wang, Xiaogong
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supporting information
p. 5556 - 5558
(2013/07/26)
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- Star-shaped molecules containing both azo chromophores and carbazole units as a new type of photoresponsive amorphous material
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We synthesized a series of star-shaped molecules containing both azo chromophores and carbazole units (nCz-AZ-X), where n is the number of carbazole units (n = 3 and 6) and X represents cyano (CN) and nitro (NT) as the electron-withdrawing groups on the azobenzenes. The azo compounds existed as amorphous solids at room temperature with glass transition temperatures (T g) of 89, 86, 74 and 73 °C for 3Cz-AZ-CN, 3CZ-AZ-NT, 6Cz-AZ-CN and 6Cz-AZ-NT, respectively. Thin solid films of the azo molecular glasses were obtained by spin-coating. The formation of the photoinduced self-structured surface patterns was investigated by irradiating the solid thin films of the azo molecular glasses with a uniform laser beam (532 nm, 200 mW cm-2) at normal incidence. The formation of surface-relief-gratings (SRGs) was studied by exposing the thin films to an interference pattern of the laser beams (532 nm, 80 mW cm-2). The formation of both the self-structured surface patterns and SRGs showed a close correlation with the electron-withdrawing groups of the azo chromophores and the content of the carbazole units in the molecules. The development of these new star-shaped molecules can add a new member to the category of azo molecular glasses and lead to a deeper understanding of the photoinduced effects and their correlation with molecular structures. The Royal Society of Chemistry 2013.
- Yin, Jianjun,Ye, Gang,Wang, Xiaogong
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p. 3794 - 3801
(2013/07/27)
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- Substituent effects on the thermal cis-to-trans isomerization of 1,3-diphenyltriazenes in aqueous solution
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The thermal cis-to-trans isomerization of some symmetrically p,p′-disubstituted 1,3-diphenyltriazenes has been studied by means of laser-flash photolysis techniques. The geometric isomerization is catalyzed by general acids and general bases as a result of acid/base-promoted 1,3-prototropic rearrangements. Acid catalysis becomes more prominent as the electron-donating character of the para substituent increases, while base catalysis becomes more important as the electron-withdrawing character of the para substituent increases. In addition, the rate ascribed to the interconversion of neutral cis rotamers through hindered rotation around the nitrogen-nitrogen single bond is found to decrease as the electron-withdrawing character of the para substituent increases. Rates of interconversion of neutral cis rotamers are also found to decrease with decreasing solvent polarity, which is indicative of the involvement of a polar transition state. On the other hand, kinetic investigations of the acid-catalyzed decomposition of target triazenes are consistent with an A1 mechanism.
- Chen, Nan,Barra, Monica,Lee, Ivan,Chahal, Navjot
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p. 2271 - 2277
(2007/10/03)
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