Energy transfer in aggregates of bacteriochlorophyll c self-assembled with azulene derivatives?

Physical Chemistry Chemical Physics Pub Date: 2014-06-23 DOI: 10.1039/C4CP01311E

Abstract

Bacteriochlorophyll (BChl) c is the main light-harvesting pigment of certain photosynthetic bacteria. It is found in the form of self-assembled aggregates in the so-called chlorosomes. Here we report the results of co-aggregation experiments of BChl c with azulene and its tailored derivatives. We have performed spectroscopic and quantum chemical characterization of the azulenes, followed by self-assembly experiments. The results show that only azulenes with sufficient hydrophobicity are able to induce aggregation of BChl c. Interestingly, only azulene derivatives possessing a conjugated phenyl ring were capable of efficient (～50%) excitation energy transfer to BChl molecules. These aggregates represent an artificial light-harvesting complex with enhanced absorption between 220 and 350 nm compared to aggregates of pure BChl c. The results provide insight into the principles of self-assembly of BChl aggregates and suggest an important role of the π–π interactions in efficient energy transfer.

Graphical abstract: Energy transfer in aggregates of bacteriochlorophyll c self-assembled with azulene derivatives
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