Modelling Photosynthesis with Zn^II-Protoporphyrin All-DNA G-Quadruplex/Aptamer Scaffolds

All-DNA scaffolds act as templates for the organization of photosystem I model systems. A series of DNA templates composed of Zn^II-protoporphyrin IX (Zn^IIPPIX)-functionalized G-quadruplex conjugated to the 3′- or 5′-end of the tyrosinamide (TA) aptamer and Zn^IIPPIX/G-quadruplex linked to the 3′- and 5′-ends of the TA aptamer through a four-thymidine bridge. Effective photoinduced electron transfer (ET) from Zn^IIPPIX/G-quadruplex to bipyridinium-functionalized tyrosinamide, TA-MV²⁺, bound to the TA aptamer units is demonstrated. The effectiveness of the primary ET quenching of Zn^IIPPIX/G-quadruplex by TA-MV²⁺ controls the efficiency of the generation of TA-MV^+.. The photosystem-controlled formation of TA-MV^+. by the different photosystems dictates the secondary activation of the ET cascade corresponding to the ferredoxin-NADP⁺ reductase (FNR)-catalysed reduction of NADP⁺ to NADPH by TA-MV^+., and the sequestered alcohol dehydrogenase catalysed reduction of acetophenone to 1-phenylethanol by NADPH.