DNA-Organized Light-Harvesting Antennae: Energy Transfer in Polyaromatic Stacks Proceeds through Interposed Nucleobase Pairs.
 

DNA-based light-harvesting antennae composed of light-collecting phenanthrenes and pyrene acceptors were synthesized and investigated. Excitation of phenanthrene leads to energy transfer to pyrene which then results in pyrene emission. Energy transfer is observed if the stack of phenanthrene units is interrupted by up to five DNA base pairs. The separation by one and two base pairs shows no decrease in energy transfer efficiency compared to a continuous phenanthrene stack. The light-harvesting antenna interrupted by one base pair has the highest efficiency of all tested duplexes. A separation by 3 to 5 base pairs leads to a gradual decrease in efficiency but energy transfer is still detected with 5 intervening base pairs. The data demonstrate that it is possible to assemble phenanthrene-based light-harvesting antennae which are mixed with natural DNA base pairs. This extends the range of potential designs and applications of DNA-based artificial light-harvesting complexes.