7-Azaindole is a molecule which undergoes excited-state proton-transfer in alcohol solvents (12). Tautomer luminescence arises from double-proton-transfer in a cyclical hydrogen-bonded complex between 7-azaindole and one alcohol molecule. The lack of 7-azaindole tautomer luminescence in water solvents is thought to be unusual since alcohol and water are both hydroxyllic solvents. We have shown that tautomer fluorescence can be detected in ether solutions that have been saturated with water. The position of the fluorescence is identical to that in ethanol. The formation of the hydrogen-bonded 7-azaindole complex in dilute water solutions has been attributed to the presence of monomer and small clusters of water molecules in these dilute solutions. In liquid water 7-azaindole cannot effectively compete with the extended network of water hydrogen bonds for monomeric water, and excited-state proton-transfer cannot occur. / We also have proposed that the excited 7-azaindole can form an exciplex with one alcohol molecule. This exciplex is directly analogous to the indole:alcohol exciplex (33) in a number of ways. Dramatic quenching of the exciplex luminescence can be explained by postulating the ejection of an electron by the exciplex upon deactivation. We have found luminescence yield effects and picosecond lifetime dependences on the acidity and state of aggregation of the alcohol which support this hypothesis. A deuterium isotope effect also has been observed. / 3-Hydroxyflavone can undergo intramolecular excited-state proton-transfer in hydrocarbon solvents. 5-Hydroxyflavone, however, exhibits no luminescence under similar conditions. An investigation of the extinction coefficients of these molecules and flavone, in addition to their luminescence properties and resonance Raman spectra, has allowed us to propose that in hydrocarbon solvents, the ('1)n, (pi)* state is lowest in flavone, the ('1)n, (pi)* state and the ('1)(pi), (pi)* state are degenerate in 5-hydroxyflavone, and that the ('1)(pi), (pi)* is lowest in 3-hydroxyflavone. The consequence of the degeneracy of the first two excited states in 5-hydroxyflavone results in a pseudo Jahn-Teller Splitting and rapid radiationless transition to the ground state. / Source: Dissertation Abstracts International, Volume: 42-10, Section: B, page: 4076. / Thesis (Ph.D.)--The Florida State University, 1981.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_74675 |
| Contributors | COLLINS, SUSAN TRACY., Florida State University |
| Source Sets | Florida State University |
| Detected Language | English |
| Type | Text |
| Format | 160 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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