Synthesis, Photoresponsive Behavior And Control On Aggregate Morphology Of Azo-perylene Bisimide Dyads

Application of organical functional material in optoelectronic devices hasappealed to more and more researchers. Among these organics, perylene diimides havebeen widely used in optoelectronic devices due to their unique conjugate structure andexcellent optoelectronic properties. Photoresponsive properties of azo compound giveit great application prospect in the field of optical devices. Therefore, it has significantvalue in science and application to realize the integration and complementation of theproperties of perylene bisimide and azo group, through the method of buildingazo-perylene bisimide dyad by perylene bisimide and azo group in different ways. Thisthesis designed and synthesized four kinds of perylene bisimide derivatives modifiedby N-azo substituent in the imide positions. The photoresponsive behavior wasresearched along with the morphology and structure of aggregates obtained bydifferent assembly methods, the light-controlled self-assemble morphology and thestructure of these derivatives was further discussed. The details are summarized asfollows:1. Target productⅠwas received through condensation of p-aminoazobenzenewith1,6;7,12-tetra(4-tert-butyl phenoxy)-3,4;9,10-perylene tetracarboxylicdianhydride; Reaction between bromododecane and4-hydroxy-4’-nitro-azobenzenewas implemented, then compound3was received from reduction. Condensation of3with1,6;7,12-tetra(4-tert-butyl phenoxy)-3,4;9,10-perylene tetracarboxylicdianhydride gave the target product Ⅱ.3,5-didodecyloxybenzyl bromide wassynthesized by multistep organic reactions including etherification and brominationfrom3,5-dihydroxybenzyl alcohol. Etherification of3,5-didodecylbenzyl bromidewith4-hydroxy-4’-nitro-azobenzene, following reduction, new azo compounds6containing amine was then obtained. Condensation of6with1,6;7,12-tetra(4-tert-butyl phenoxy)-3,4;9,10-perylene tetracarboxylic dianhydride and3,4;9,10-perylene tetracarboxylic dianhydride were carried out respectively to affordtarget product Ⅲ, Ⅳ; Molecular structures of the four target products were identifiedthrough1H NMR,1C NMR, and IR.2. Researches on the light responsive behavior ofⅠ, Ⅱ, Ⅲ and Ⅳ showedthat: absorption peak of trans-azo groups appeared at320nm~358nm, which varied acertain degree with the electronic structure change of-N=N-; Absorption value reduced gradually with the UV light for their photoinduced trans-cis isomerism and theisomerism rate decreased with increasing concentration; Absorption peak of perylenebisimide in compoundⅠ, Ⅱ, Ⅲ showed at590nm,550nm and450nm, while thesame kind of peak of Ⅳlocated at525nm,490nm,460nm, following a shoulder peakat550nm; Absorption of perylene bisimide was not affected by UV light and did notchange with the N-azo substituent groups. Fluorescence emission spectra of these fourcompounds had different rules with extension of UV light time, and the fluorescenceintensity was greatly influenced by the concentration of the compounds.3. Researches on the aggregates received by phase transfer method showed that:all of the target products formed regular nanostructures in two-phase solvent system(methanol/chloroform). While the specific morphology ofⅠ, Ⅱ, Ⅲ and Ⅳ weredifferent obviously from each other, which was attributed to the various substituentgroups.Ⅰformed sheet structure with a large aspect ratio; Ⅱreceived regular sheetstructure; Aggregates of Ⅲ were short nanofiber and Ⅳ were short rodlikenanostructure. The structure regularity and aspect ratio increased with the decreasingvolume ratio of chloroform.4. Researches on the aggregates of azo-perylene bisimide dyads obtained throughrapid solution dispersion showed that: Aggregates gained by this method largelydiffered from that by phase transfer method. Ⅰgot quadrangle structure with smallsize; Ⅱformed entangled fibers with width of about0.5μm and a large aspect ratio;Aggregates of Ⅲ were short nanofiber with a small aspect ratio while Ⅳ hadirregular structure. Similar to the phase transfer method, with the increasing of volumeratio of methanol, aggregates had better regularity and lager size.5. Finally, the effects of UV light on rapid solution dispersing process and themorphology of aggregates were investigated. The result showed that, the aggregatesstructures and morphology in the absence of UV irradiation were more regular than thestucture and morphology in the presence of UV irradiation. The result of absorptionspectra showed that the π-π interaction of aggregated molecule of the azo-perylenebisimide dyads was weaker after the presence of UV irradiation.The results all above showed that, the difference in N-azo substituent of perylenebisimide result in the difference in its photoresponsive behavior and the morphology ofaggregates. And the UV light has important influence on the morphology of aggregatesof perylene bisimide derivatives modified by azo group. These studies establishedexperimental basis for further exploration of the mechanism of interaction between azogroup and perylene bisimide, and provided certain scientific foundation for the controlof the property of photoeletric device based on azo-perylene disimide dyads.