Efficiency of excitation energy transfer from artificial bacteriochlorophyll c aggregates to bacteriochlorophyll a acceptor
Abstrakt
Aggregates of bacteriochlorophyll (BChl) c can be found in chlorosomes, the main light-harvesting antennas of green photosynthetic bacteria. The aggregates do not contain any proteins and self-assemble into large structures (on the order of 100 nm).
The lack of proteins makes it possible for the aggregates to self-assemble also in vitro, and to modify their properties on demand. Therefore, they are a promising piece of puzzle in the developing field of artificial light harvesting.
To improve their spectral coverage, we are incorporating other natural pigments into the aggregate structure. Primarily, we are interested in pigments absorbing in the green region of the solar spectrum (like carotenoids), which is otherwise not covered by BChl c.
In our previous work [Malina et al., 2021, Scientific Reports 11, 18739], we have found that the excitation energy in chlorosomes and artificial aggregates of BChl c remains delocalized for a relatively long time after absorption (tens of ps). This contributes to a higher efficiency of excitation energy transfer not only within the aggregates, but also out of the aggregates.
To address the transfer of energy out of the aggregates, we are incorporating an acceptor of excitation energy into the artificial aggregates. Inspired by natural chlorosomes, we are using BChl a.
Its S1 energy is slightly lower than for BChl c aggregates, which makes it an ideal candidate to direct the energy flow from BChl c to BChl a. In this contribution, we will present results of experiments on the efficiency of energy transfer from the artificial BChl c aggregates to the incorporated BChl a, which reaches up to 95 % for a certain type of artificial aggregates.