- Recombination of lophyl radicals in pyrrolidinium-based ionic liquids
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The recombination of photolytically generated lophyl radicals has been investigated by UV/Vis spectroscopy in 1-alkyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imides (NTf2) in comparison with 1-butyl-3-methylimidazolium NTf2, dimethyl sulfoxide, and triacetin. The 1-alkyl-1-methylpyrrolidinium-based ionic liquids contain an alkyl substituent varying between butyl and decyl groups. Optically pure ionic liquids are used in these studies. Temperature-dependent investigation of lophyl radical recombination shows an increase in the radical recombination rate with increasing temperature in each solvent, which is caused by decreasing viscosity with increasing temperature. Furthermore, the viscosity of the 1-alkyl-1-methylpyrrolidinium NTf2 increases nearly linearly within the row of these ionic liquids. In contrast, the recombination of the photolytically generated lophyl radicals is significantly faster in the ionic liquids than in the traditional organic solvents under investigation. Moreover, the recombination rate increases with the length of the alkyl chain bound at the cation of the ionic liquid at a given temperature. This may be caused by an increase in the extent of lophyl radical recombination within the solvent cage. Solvent cage effects dominate in the case of lophyl radical recombination in ionic liquids bearing a long alkyl chain or if the temperature is near the melting temperature of the ionic liquid. The positive value of the activation entropy supports this hypothesis. The results obtained are important for discussion of bimolecular radical reactions in ionic liquids. Rate increases: Long alkyl chains bound at the cation of 1-alkyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ionic liquids change the steric requirements on the transition state of the bimolecular lophyl radical recombination reaction (see picture). Recombination of the photolytically generated radicals is faster in the ionic liquids than in traditional organic solvents. Copyright
- Berdzinski, Stefan,Horst, Joachim,Strassburg, Petra,Strehmel, Veronika
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p. 1899 - 1908
(2013/07/26)
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- Photoinduced diffusive mass transfer in o-Cl-HABI amorphous thin films
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The first demonstration of photoinduced surface relief grating formation using amorphous thin films composed of a radical dissociative photochromic compound, 2,2′-di(ortho-chlorophenyl)-4,4′,5,5′- tetraphenylbiimidazole, show that mass transfer occurred from the UV-light-irradiated area to the shaded area by patterned light irradiation (365 nm).
- Kikuchi, Azusa,Harada, Yukari,Yagi, Mikio,Ubukata, Takashi,Yokoyama, Yasushi,Abe, Jiro
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body text
p. 2262 - 2264
(2010/07/08)
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- Formation of hexaarylbiimidazole heterodimers via the cross recombination of two lophyl radicals
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The formation of hexaarylbiimidazole heterodimers has been investigated in detail by X-ray crystallography and 1H NMR spectroscopy. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2009.
- Kimoto, Atsushi,Niitsu, Shimpei,Iwahori, Fumiyasu,Abe, Jiro
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experimental part
p. 1339 - 1342
(2009/09/24)
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