Y. Xin
2013
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Journal
Journal of Beijing University of Chemical Technology
Abstract
3,5-Didodecylbenzyl bromide has synthesized from 3,5-dihydroxybenzyl alcohol in a multistep process including etherification and bromination.Etherification of 3,5-didodecylbenzyl bromide and 4-hydroxy-4'-nitro-azobenzene,followed by reduction,afforded a new azo compound 6 containing an amine group.Condensation reaction of 6 with 3,4;9,10-perylenetetracarboxylic dianhydride was carried out to afford a new azo-perylenebisimide dyad 7.The influence of UV irradiation time and concentration of 7 on its optical and physical properties were investigated by UV-vis spectroscopy and fluorescence spectroscopy.The trans-to-cis photoisomerization of the azo moiety by UV irradiation was retarded by a high concentration of dyad 7 in chloroform.The morphologies of aggregates obtained by phase transfer assembly between methanol and chloroform were examined.Well-defined rod-like nanostructures of 7 were observed when the volume ratio of methanol and chloroform was 7 ∶ 1 or 5 ∶ 1.The light-controlled self-assembly behavior of 7 was further investigated.Aggregates formed in the absence of UV irradiation were more regular than those formed under UV irradiation.Furthermore,absorption spectra demonstrated that weaker ππ stacking interactions are involved in the aggregates obtained by exposure of 7 to photoirradiation at 365nm.These results show that the trans-to-cis photoisomerization of the azo moiety induced changes in molecular geometry,leading to loss of order of the molecular arrangement and difficulty in forming low dimensional nanostructures.