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Self-assembly and excited energy transfer in bacteriochlorophyll aggregates
Pospíšil, Petr ; Pšenčík, Jakub (advisor) ; Vácha, František (referee)
Bacteriochlorophyll c (BChl c) belongs among photosynthetic pigments. It is found in lightharvesting complexes of green photosynthetic bacteria in the form of self-assembled aggregates. It is possible to prepare BChl c aggregates also in vitro in aqueous solutions, in the presence of certain non-polar molecules (e.g. lipids or carotenoids). In this work, artificial light-harvesting antenna was prepared composed of BChl c and selected azulene derivative. The aggregation of BChl c with azulene enhances the absorption in the near UV region compared to BChl c. Fluorescence spectroscopy was used to study an efficiency of energy transfer from azulene to BChl c. The procedure used was based on fluorencence excitation spectra measurement, and a comparison with absorption 1-T spectra. The measurements were complicated by anomalous fluorencence of azulene, which occurs from the S2 state. Furthermore, the reference diode in the fluorescence spectrometer did not correct properly the signal in the near UV region, where azulene absorbs. The problem was partially solved by preparing the new correction files using selected laser dyes. Excitation spectra demonstrate the presence of the energy transfer from azulene to BChl c, however, it was not yet possible to satisfactorily quantify its efficiency.
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