Spektroskopia i fotofizyka pochodnych 5-deazaalloksazyny. Ujęcie eksperymentalne i teoretyczne
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Date
2015-06-15
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Spectroscopy and photophysics of 5-deazaalloxazine derivatives. Experimental and theoretical approaches
Abstract
Właściwości spektralne i fotofizyczne 5-deazaalloksazyny (5DAll), jej metylowych pochodnych, 10-etylo-5-deazaizoalloksazyny (10Et-5DIzoAll) oraz monometylowych pochodnych alloksazyny o budowie czteropierścieniowej zostały określone przy zastosowaniu metod eksperymentalnych oraz teoretycznych. Struktury elektronowe cząsteczek oraz przewidywane energie przejść singlet → singlet, singlet → tryplet oraz tryplet → tryplet zostały wyznaczone głównie przy wykorzystaniu metod DFT oraz ab-initio. W przypadku pochodnych 5DAll oraz badanych pochodnych alloksazyny określono, iż najniższy wzbudzony stan singletowy ma charakter π,π*. Stany trypletowe wybranych cząsteczek zostały scharakteryzowane w acetonitrylu i wodzie. Dla pochodnych 5DAll wyznaczono czas życia stanu trypletowego, który zanikał w mikrosekundowej skali czasowej. Badane pochodne 5DAll zostały zdefiniowane jako wydajne sensybilizatory tlenu singletowego. Pokazana została również użyteczność synchronicznej spektroskopii fluorescencyjnej w badaniach różnych pochodnych flawin i 5-deazaflawin.
Spectral and photophysical properties of 5-deazaalloxazine (5DAll), its methyl derivatives, 10-ethyl-5-deazaisoalloxazine (10Et-5DIzoAll) and alloxazine derivatives with four ring structure have been investigated using experimental and theoretical approach. UV/Vis absorption and emission spectroscopy have been used to describe the electronic structure of studied molecules. Values of the fluorescence quantum yield determined are relatively high, the fluorescence lifetimes are relatively long comparing to respective alloxazines. Both spectral and photophysical properties of 10Et-5DIzoAll and 5DAll derivatives are different as compared to the respective iso- and alloxazines. The electronic structures of molecules and the predicted energies of singlet → singlet, singlet → triplet and triplet → triplet transitions have been determined using the DFT and ab-inito methods. For 5DAll derivatives and for alloxazine derivatives with four ring structure the S0→S1 transition has been found having π,π* character. The triplet lifetime for 5DAll derivatives have been found in a microsecond time range. It has been found that 5DAll derivatives can be used as efficient photosensitizers of singlet oxygen. The applications of the synchronous fluorescence spectroscopy have been implemented, especially in studies of mixtures of flavin and 5-deazaflavin type of compounds.
Spectral and photophysical properties of 5-deazaalloxazine (5DAll), its methyl derivatives, 10-ethyl-5-deazaisoalloxazine (10Et-5DIzoAll) and alloxazine derivatives with four ring structure have been investigated using experimental and theoretical approach. UV/Vis absorption and emission spectroscopy have been used to describe the electronic structure of studied molecules. Values of the fluorescence quantum yield determined are relatively high, the fluorescence lifetimes are relatively long comparing to respective alloxazines. Both spectral and photophysical properties of 10Et-5DIzoAll and 5DAll derivatives are different as compared to the respective iso- and alloxazines. The electronic structures of molecules and the predicted energies of singlet → singlet, singlet → triplet and triplet → triplet transitions have been determined using the DFT and ab-inito methods. For 5DAll derivatives and for alloxazine derivatives with four ring structure the S0→S1 transition has been found having π,π* character. The triplet lifetime for 5DAll derivatives have been found in a microsecond time range. It has been found that 5DAll derivatives can be used as efficient photosensitizers of singlet oxygen. The applications of the synchronous fluorescence spectroscopy have been implemented, especially in studies of mixtures of flavin and 5-deazaflavin type of compounds.
Description
Wydział Chemii
Sponsor
Praca doktorska jest współfinansowana ze środków badawczych Narodowego Centrum Nauki:
- projekt badawczy z zakresu badań podstawowych "Etiuda" (2013/08/T/ST4/00640); kierownik: mgr Mateusz Gierszewski
- projekt badawczy z zakresu badań podstawowych "Opus" (2012/05/B/ST4/01207); kierownik: prof. dr hab. Marek Sikor
Keywords
Spektroskopia, Spectroscopy, Fotofizyka, Photophysics, Flawiny, Flavin, Tlen singletowy, Singlet oxygen, 5-deazaalloksazyny, 5-deazaalloxazines