Intramolecular Mobility Affects the Energy Migration from Quantum Dots to Reaction Centers of Photosynthesizing Bacterium Rb. sphaeroides.

The temperature dependence of the efficiency of energy migration from the CdSe/CdS/ZnS quantum dots (QDs) with a fluorescence maximum at 580 nm to the reaction centers (RCs) of the bacteria Rb. sphaeroides is practically constant over the temperature range from 100 to ~230-240 K but then decreases 2.5-3 times as temperature further increases to 310 K. The analysis on this dependence on the basis of Förster's theory showed that the major changes in the energy transfer efficiency are associated with the temperature change in the quantum yield of QD fluorescence, which is due to the activation of intramolecular mobility in the RC structure.