Excited-state proton transfer reactions are investigated for three different molecular species, 3-hydroxyflavone, 7-azaindole, and lumichrome. Both steady-state and picosecond spectroscopic techniques are used to establish the dominant role of solvent structure and dynamics in the tautomerization mechanisms of these systems. The explicit consideration of a ground-state hydrogen-bonding equilibrium together with the subsequent excited-state solvent/solute relaxation dynamics allows for a precise interpretation of the processes which occur in these molecules following electronic excitation. / Proton transfer in 3-hydroxyflavone is formally an intramolecular process. The tautomerization process in this molecule, however, is found to depend sensitively on interactions with the surrounding solvent molecules. Distinct ground-state species which give rise to different excited-state luminescence behavior are identified and characterized. In the absence of hydrogen-bonding perturbations the tautomerization in 3-hydroxyflavone is rapid, efficient, and effectively independent of both temperature and viscosity. / The isolated 7-azaindole molecule possesses no direct pathway for tautomerization. If proton transfer is to occur it must do so through a molecular bridge of some sort. This class of excited-state reactions is refered to as pseudointramolecular proton transfer to distinguish it from the purely intramolecular case. In alcoholic solvents the proton transfer in 7-azaindole takes place in cyclically hydrogen-bonded complexes. Although the physical mechanisms differ, the dynamical aspects of the tautomerization process in 7-azaindole are strikingly similar to those of 3-hydroxyflavone. The tautomerism is intimately coupled to the structure and dynamics of the surrounding solvent cage. / Lumichrome provides a particularly interesting case of pseudo-intramolecular proton transfer. Tautomerization takes place in the solvents pyridine, glacial acetic acid, and in the various derivatives of these. The roles of solvent structure and dynamics on the proton transfer process in these systems are investigated. / Source: Dissertation Abstracts International, Volume: 46-04, Section: B, page: 1188. / Thesis (Ph.D.)--The Florida State University, 1985.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_75580 |
| Contributors | MCMORROW, DALE PATRICK., Florida State University |
| Source Sets | Florida State University |
| Detected Language | English |
| Type | Text |
| Format | 169 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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