Synthesis And Characterization Of Ribbon-type Conjugated Oligomers Containing Pyrene Unit

Polycyclic aromatic hydrocarbons?PAHs? as well defined “piece of graphite” have been exploited in various organic electronic devices including field-effect transistors, photovoltaic devices, and light-emitting diodes. Ribbon-type polymers and oligomers possessing two dimensionally planar conformation, high electron delocalization, and functional optic-electronic properties have been attractted great interesting. Pyrene, as a typical polycyclic structure of the conjugate molecule, ?-?* transition is easy to occur. Pyrene has been used to architecture ladder or ribbon-type polymers and oligomers. We use pyrene as the smallest peri to synthesis a series of ?-conjugated graphene ribbon oligomers?W1-W₃? by the typical strategy of PAH production. Then on the base of these, ribbon-type oligomers with larger graphene are designed.The main contents are as follows:1. Ribbon-type oligomers were synthesized use 2, 7-Di-tert-butyl and 4, 4'-ditert-butyl-biphenyl as repeated units. Proper peri was prepared by reaction with Br2 and bis?pinacolato?diboron. We synthesized precursor B₁₂, B₁₃ and B₁₄ by Suzuki coupling reaction. And we underwent cyclodehydrogenation to give the ribbon-type oligomers W1?W₂ and W₃. The catalyst for B₁₂ is FeCl₃, while for the other two is DDQ/ BF₃·EtO₂.2. These three oligomers were tested by the UV spectrum and the fluorescence spectrum. Oligomers exhibited strong blue fluorescence emission. Both in solution and thin film, there were significant redshift for absorption peak and fluorescence peak with the increase of repeated units. But the fluorescence emission curve in thin film was quite different from that in solution, mainly because ?-? stacking interactions existed in thin film. We analysed the TGA curve and considered that oligomers W1, W₂ and W₃ had good thermal staility in nitrogen atmosphere.3. On the basis of C hapter 2, we designed and synthesized different peri and ribbon-type oligomers W₄ and W₅, Which were greater planar, higher conjugated, by classical polycyclic aromatic hydrocarbons preparation. Finally, appropriate polyphenylene precursor B19 and B21 were obtained, and tried to carry out the cyclodehydrogenation under different conditions, such as FeC l₃, MoC l5, DDQ/BF₃·EtO₂, temperatures and reaction time. Unfortunately, we only got the chloro-compound.