偶氮基团修饰的苝酰亚胺染料的合成及其光响应行为

Synthesis and photoresponsive behavior of a novel azo-modified perylene bisimide dye

以3,5-二羟基苯甲醇为原料,经醚化、溴代反应得到3,5-二(十二烷氧基)苄基溴,然后与4-羟基-4'-硝基偶氮苯反应,再还原得到含氨基的偶氮化合物6,最后与3,4;9,10-苝四甲酸二酐缩合得到新型偶氮-苝酰亚胺二元染料7。考察了紫外光光照时间及浓度等因素对偶氮-苝酰亚胺二元染料光学性能的影响,结果表明浓度越大,偶氮生色团由反式结构向顺式结构的转变速度越慢;对相转移法组装形成的聚集体形貌结构的研究表明,当甲醇与三氯甲烷体积比为7∶1或5∶1时,更易形成较规整的短棒状结构;比较研究紫外光光照和未光照下快速溶剂扩散法组装形成的聚集体形貌结构发现,光照下制备的聚集体结构的规整性不及未光照下制备的;吸收光谱表明在光照下组装的聚集体分子间π-π堆积作用更弱,这是由于偶氮基团由反式结构向顺式结构的转变导致分子空间几何构型的变化,破坏了分子堆积的有序性,不利于低维功能材料的形成。

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-azo- benzene, 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 investiga- ted 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 ob- tained by phase transfer assembly between methanol and chloroform were examined. Well-defined rod-like nano- structures of 7 were observed when the volume ratio of methanol and chloroform was 7：1 or 5： 1. The light-con- trolled 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 π- stacking interactions are involved in the aggregates obtained by exposure of 7 to photoirradiation at 365 nm. These results show that the trans-to-cis photoisomerization of the azo moiety induced changes in molecular geometry, lead- ing to loss of order of the molecular arrangement and difficulty in forming low dimensional nanostructures.