The Photoisomerization of <I>cis</I>-Azobenzene in the Presence of Iodine
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概要
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The conversion of <I>cis</I>-azobenzene in a <I>n</I>-hexane solution to its trans-isomer in the presence of iodine has been studied by light irradiation. The experiments with wavelengths of 313 and 436 mμ at −78°C have shown that the excitation of the molecular complex formed between <I>cis</I>-azobenzene and iodine, by its charge-transfer transition or by the blue-shifted absorption of complexed iodine, yields <I>trans</I>-azobenzene with a quantum yield independent of the composition of the solution. By comparing this finding with the results previously obtained for the cis-trans photoiso-merization of free azobenzene in <I>n</I>-hexane, a probable mechanism has been presented: CI<SUB>2</SUB> + hν → CI<SUB>2</SUB><SUP>*</SUP>, CI<SUB>2</SUB><SUP>*</SUP> → C<SUP>*</SUP> + I<SUB>2</SUB> and C<SUP>*</SUP> → T, where C and T denote <I>cis</I> and <I>trans</I>-eizoben-zene respectively.<BR>The results obtained at 0°C by irradiation at wavelengths of 546 and 577 mμ, which are solely absorbed by free iodine in the solution, are similar to those previously obtained for stilbene; they may, therefore, be explained in a similar way, i. e., by the photochemical dissociation of free iodine, followed by the iodine atom-catalyzed isomerization of <I>cis</I>-azobenzene.
- 公益社団法人 日本化学会の論文
著者
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Toyama Osamu
Department of Applied Chemistry College of Engineering, The University of Osaka Prefecture
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Yamashita Shigeru
Department of Chemistry College of General Education The University of Osaka Prefecture