Pochodne ryboflawiny jako fotosensybilizatory tlenu singletowego
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2010-05-21T09:25:41Z
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The riboflavin derivatives as the singlet oxygen photosensitizers
Abstract
Praca dotyczy spektralnych, fotofizycznych i fotochemicznych właściwości kilku pochodnych ryboflawiny – 3-benzylo-lumiflawiny, izo-6,7-ryboflawiny, 5-deaza-ryboflawiny oraz 3-metylo-tetraacetylo-ryboflawiny. Dane eksperymentalne dotyczące właściwości spektralnych związków we wzbudzonych stanach singletowych i trypletowych porównano z danymi teoretycznymi, uzyskanymi za pomocą obliczeń metodą TD-DFT. Rezultaty obliczeń dla stanów singletowych wykazują dobrą zgodność z danymi eksperymentalnymi i dobrze charakteryzują energie i konfiguracje stanów wzbudzonych.Zbadano oddziaływania związków z tlenem z wytworzeniem tlenu singletowego w reakcji fotosensybilizacji. Wyznaczono parametry fotofizyczne, m.in. czas życia stanu trypletowego i wydajność tworzenia tlenu singletowego. Zarówno ryboflawina jak i pozostałe badane pochodne są dobrymi fotosensybilizatorami reakcji tworzenia tlenu singletowego. Zbadano również właściwości absorpcyjne i emisyjne pochodnych w postaci polikrystalicznej. Wykonano wstępne badania fotochemiczne analogów ryboflawiny w metanolu. Wyznaczono wydajność kwantową procesu fotolizy i zaproponowano struktury niektórych fotoproduktów. 3-Metylo-tetraacetylo-ryboflawina wykazuje znacznie większą stabilność fotochemiczną niż ryboflawina, co pozwala na rozszerzenie zastosowań związku jako modelowego w badaniach ryboflawiny i jej pochodnych.
Presented dissertation is focused on the spectral, photophysical and photochemical properties of flavin analogues – 3-benzyl-lumiflavin, izo-6,7-riboflavin, 5-deaza-riboflavin and 3-methyl-riboflavin tetraacetate. Interesting properties in both singlet and triplet excited states of investigated analogues in solution were discussed in comparison with theoretical calculations obtained with using experimental results and theoretical predictions on the basis of TD-DFT method. For the singlet states theoretical and experimental results remain in a good agreement with each other. The special regard were given to the role of the investigated compounds as photosensitizers of singlet oxygen production. The triplet state quantum yield and quantum yield of singlet oxygen production were determined. Moreover the absorption and emission properties were studied for the compounds in the solid state. Some preliminary research have been done to investigate the photochemical reactions of the studied compounds in methanolic solutions. There were determined a photolysis quantum yield and the structures of some photoproducts were proposed.3-Methyl-riboflavin tetraacetate have been shown as much more resistant to photodegradation compared to riboflavin and the other derivatives. Riboflavin and the other studied compounds have appeared to be a good photosensitizers of singlet oxygen production.
Presented dissertation is focused on the spectral, photophysical and photochemical properties of flavin analogues – 3-benzyl-lumiflavin, izo-6,7-riboflavin, 5-deaza-riboflavin and 3-methyl-riboflavin tetraacetate. Interesting properties in both singlet and triplet excited states of investigated analogues in solution were discussed in comparison with theoretical calculations obtained with using experimental results and theoretical predictions on the basis of TD-DFT method. For the singlet states theoretical and experimental results remain in a good agreement with each other. The special regard were given to the role of the investigated compounds as photosensitizers of singlet oxygen production. The triplet state quantum yield and quantum yield of singlet oxygen production were determined. Moreover the absorption and emission properties were studied for the compounds in the solid state. Some preliminary research have been done to investigate the photochemical reactions of the studied compounds in methanolic solutions. There were determined a photolysis quantum yield and the structures of some photoproducts were proposed.3-Methyl-riboflavin tetraacetate have been shown as much more resistant to photodegradation compared to riboflavin and the other derivatives. Riboflavin and the other studied compounds have appeared to be a good photosensitizers of singlet oxygen production.
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Wydział Chemii: Pracownia Fotochemii Stosowanej
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Keywords
Flawiny, Flavins, Ryboflawina, Riboflavin, Tlen singletowy, Singlet oxygen, Fotosensybilizacja, Photosensitization, Fotoliza, Photolysis