| Perylene-3,4;9,10-tetracarboxylic diimide(PDI)derivatives have attracted increasing attention in the past decade due to their potential applications in molecular electronics and photo devices.These dyes have generated great interest because of their outstanding photochemical and thermal stability,ease of synthetic modification,and desirable optical and redox characteristics.Driven by their use in many different applications,the structure of PDIs has been modified by introducing side groups to get appropriate PDIs bearing desirable optical and redox features.Usually,two different methods were adopted to achieve the chemical modification of PDIs.One is to introduce substituents at N atoms of imide groups,which does not significantly affect the optical and electronic properties because of the nodes in the HOMO and LUMO at the imide nitrogen.Another way is to introduce the substituents to the perylene core of PDI,i.e.,the so-called bay position;with electron-donor or electron-acceptor groups,such modification will greatly change the properties of PDIs. However,The substituents that have previously been incorporated onto the bay positions of PDIs are limited to phenoxy groups,aryls,cyclic secondary amines,cyano groups,and halogens.So,in this paper,we described the synthesis and properties of a series of novel PDIs bearing alkoxy/alkylthio/primary alkylamino substituents at their bay positions that appears to be no report on PDI compounds ever before.In chapter 1,the research of synthesis,properties and applications of these perylene diimide derivatives have been reviewed,and the desired PDI compounds bearing novel substituents is the innovation.The synthetic route of these novel PDIs was described in chapter 2.Nucleophilic substitution of N,N-dicyclohexyl-1,7-dibromoperylene-3,4:9,10-tetracarboxydiimide with an excess of corresponding alkanol in the presence of sodium hydride or anhydrous potassium carbonate at 90-110℃provided both di(alkoxy)- and mono(alkoxy)-substituted PDI compounds,namely,N,N-dicyclohexyl-1,7-di(alkoxy)pery lenediimide and N,N-dicyclohexyl- 1-bromo-7-alkoxyperylenediimide.It is worth pointing out that the yield of disubstituted product is always lower than that of monosubstituted,no matter how to prolong the reaction time.But by adding CTAB as the catalyst,we are able to get the disubstituted product with higher yield in comparatively short tine.Due to the stronger nucleophilicity of alkylthio groups than that of alkoxy groups,we succeeded to get alkylthio-substituted PDI compounds by phase transfer reaction that was newly developed reaction route.And according to the similar route,we got the di(phenylthio)-substituted PDI compound more easily.Starting from mono(alkoxy)-substituted PDI,nucleophilic substitution with thiol,thiophenol,or alkylamine led to the formation of unsymmetrical 1,7-di(substituted)PDI compounds with high yield.In chapter 3,we characterized these newly prepared PDI compounds by a wide range of spectroscopic methods.Electronic absorption and fluorescence studies revealed that the absorption and emission bands as well as the fluorescence quantum yield can be tuned continuously over a large range by incorporating substituents with different electron-donating abilities.And the electrochemical behavior of all the disubstituted PDI compounds was investigated by cyclic voltammetry(CV)and differential pulse voltammetry(DPV).Furthermore,we calculated these compounds with AM1 method and finded that the calculation results agreed well with the experimental findings.A series of ethynylene substituted PDI compounds at bay region was synthesized by Sonogashira reaction for the purpose of extending the aromatic rings of perylene and changing the photophysical or redox peroepties of PDI compounds to a lager extent.The optical properties of these compounds was recorded and the results are discussed in chapter 4. |
