Abstract
The work described in this thesis has been focused on synthesizing donor-acceptor chromophores with conjugated π-bridges. It has also led to the development of an alternative synthetic tool for acetylenic scaffolding. The first chapter focuses on the nitrophenol D-π-A system – A phenol in conjugation with a nitrobenzene unit. Five nitrophenols were synthesized with different π-bridges covering the features of cross-conjugation, linear conjugation, planarity, and non-planarity. I was hoping to elucidate the intrinsic properties of the π-bridges via comparison of the charge-transfer absorptions of the compounds. The measurements in solution led to the
conclusion that some of the transitions observed may not be charge-transfer
transitions, as they were not red-shifted upon deprotonation of the phenol. The results can hopefully be used in combination with future measurements in the gas phase by our collaborators in Aarhus to gain more knowledge. The second chapter describes the synthesis of a bis(dithiafulvene)-indenofluorene (a D-π-D system). The prepared compound showed chargetransfer from the dithiafulvene units to the indenofluorene π-bridge. Oxidation of the compound occurred in two one-electron events and was fully reversible. This made it possible to prepare the singly oxidized compound D+-π-D by electrolysis. This species showed two charge-transfer absorptions in the near infra-red region. One of these appeared to arise from a complex between a neutral molecule and the radical cation (a mixed-valence salt).
[BILLEDE UDELADT]
In the third chapter the reactivity of chloroalkynes is explored. A number of chloroalkynes is prepared and subjected to palladium-catalyzed cross coupling with a terminal alkyne. The chloroalkynes turned out to couple very well using the same conditions as for the Sonogashira cross-coupling. The reactivity of chloroalkynes was compared to that of Sonogashira substrates and the chloroalkynes turned out to react as fast as an aryl iodide. Some of the couplings gave reductive homo-coupling of the chloroalkyne as a byproducts. This was avoided by using a large copper to palladium ratio, and using an excess of terminal alkyne.
Vinyl iodide ≥ vinyl triflate > vinyl bromide ≥ chloroalkyne ≥ aryl iodide >
aryl triflate ≥ aryl bromide >> aryl chloride
conclusion that some of the transitions observed may not be charge-transfer
transitions, as they were not red-shifted upon deprotonation of the phenol. The results can hopefully be used in combination with future measurements in the gas phase by our collaborators in Aarhus to gain more knowledge. The second chapter describes the synthesis of a bis(dithiafulvene)-indenofluorene (a D-π-D system). The prepared compound showed chargetransfer from the dithiafulvene units to the indenofluorene π-bridge. Oxidation of the compound occurred in two one-electron events and was fully reversible. This made it possible to prepare the singly oxidized compound D+-π-D by electrolysis. This species showed two charge-transfer absorptions in the near infra-red region. One of these appeared to arise from a complex between a neutral molecule and the radical cation (a mixed-valence salt).
[BILLEDE UDELADT]
In the third chapter the reactivity of chloroalkynes is explored. A number of chloroalkynes is prepared and subjected to palladium-catalyzed cross coupling with a terminal alkyne. The chloroalkynes turned out to couple very well using the same conditions as for the Sonogashira cross-coupling. The reactivity of chloroalkynes was compared to that of Sonogashira substrates and the chloroalkynes turned out to react as fast as an aryl iodide. Some of the couplings gave reductive homo-coupling of the chloroalkyne as a byproducts. This was avoided by using a large copper to palladium ratio, and using an excess of terminal alkyne.
Vinyl iodide ≥ vinyl triflate > vinyl bromide ≥ chloroalkyne ≥ aryl iodide >
aryl triflate ≥ aryl bromide >> aryl chloride
| Originalsprog | Engelsk |
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| Forlag | Department of Chemistry, Faculty of Science, University of Copenhagen |
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| Antal sider | 140 |
| Status | Udgivet - 2013 |