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Title: Synthesis and characterisation of novel conducting films based on indolo[3,2,1-jk] carbazole systems
Author: Wharton, Stuart I.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2005
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A novel gas-phase free-radical cyclisation to carbazoles has been developed. A number of 2-nitrodiphenylamines were subjected to flash vacuum pyrolysis (FVP) to produce, after cleavage of the nitro-group, a phenyl radical that cyclises to produce carbazoles. Phenazines are formed as by-products during this FVP reaction by an electrocyclisation process involving the nitro group. Carbazole formation was favoured when electron withdrawing groups were present in the 2-nitrodiphenylamines. The cyclisation strategy was also applied to the preparation of carbolines. These were successfully obtained when the heterocyclic nitrogen was para to the amine nitrogen atom. When an ortho nitrogen atom was present, the production of carbolines required the initial radical to be generated on the heterocycle. When the radical was generated on the phenyl ring, the products were benzo-fused benzimidazoles. The gas-phase cyclisation methodology developed for the preparation of carbazoles was applied to the synthesis of the fused indole systems indolo- and pyrrole-[3,2,1-jk]carbazole. Both systems were prepared in good yield and the method was successfully applied to the production of substituted indolo- and pyrrole-[3,2,1-jk]carbazoles. Novel aza-analogues of indolo-and pyrrolo-[3,2,1-jk]carbazole were prepared for the first time. The electrochemical properties of indolo- and pyrrolo[3,2,1-jk]carbazole were studied. It was found that when both compounds were subjected to electro-oxidation, electro-active conducting films were formed on the electrode surface. the electro-oxidised indolo[3,2,1-jk]carbazole product was analysed by NMR spectroscopy and mass spectrometry and was found to consist of three dimers. The film was highly fluorescent in the blue region of the spectrum with a lifetime of the order of 10 ns, making it a potential candidate for application in display technology such as LEDs. The structures of the components of the film were confirmed by synthesising the dimers chemically using Suzuki-coupling methodology, with comparison of their NMR spectroscopic, electrochemical and fluorescence characteristics. Electro-oxidation of substituted indolo[3,2,1-jk]carbazoles was also studied and found to have similar characteristics. These studies were extended to 7-azaindolo[3,2,1-jk]carbazole and an electro-active conducting film was again formed. Like indolo[3,2,1-jk]carbazole, the film consisted of three dimers and was highly fluorescent in the blue region of the spectrum.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available