Streptavidin as a Scaffold for Light‐Induced Long‐Lived Charge Separation

Abstract Long‐lived photo‐driven charge separation is demonstrated by assembling a triad on a protein scaffold. For this purpose, a biotinylated triarylamine was added to a Ru II –streptavidin conjugate bearing a methyl viologen electron acceptor covalently linked to the N ‐terminus of streptavidin. To improve the rate and lifetime of the electron transfer, a negative patch consisting of up to three additional negatively charged amino acids was engineered through mutagenesis close to the biotin‐binding pocket of streptavidin. Time‐resolved laser spectroscopy revealed that the covalent attachment and the negative patch were beneficial for charge separation within the streptavidin hosted triad; the charge separated state was generated within the duration of the excitation laser pulse, and lifetimes up to 3120 ns could be achieved with the optimized supramolecular triad.