From natural photosynthesis to artificial photosynthesis

Mimicking the Catalytic Center for the Water-Splitting Reaction in Photosystem II

“…The whole structure of the OEC is an asymmetric Mn 4 CaO 5 -cluster. In this structure, the key component, Ca 2+ , is located in the middle of the OEC and connected to the four manganese ions through three oxide bridges and two carboxylate groups, which is consistent with our previous proposal ( Figure 2A) published in 1999 [37,38].…”

“…Different structural models were suggested to explain different experimental observations of the OEC in PSII [33][34][35][36][37]. Figure 2A shows the structural model proposed by Zhang et al in 1999 [37,38] in which, apart from all other models [33][34][35][36], the key component of calcium was suggested to be located in the middle of the OEC and connected with four manganese ions through three oxide bridges and two carboxylate groups [37]. Figure 2.…”

“…Surprisingly, the oxidation valences of the four manganese ions of all Figure 2. Scheme for the structural model [37,38] (A) and structure of the OEC [39] (B).…”

“…In order to better understand the structure and properties of the OEC as well as to develop highly efficient and cheap man-made catalysts for the water-splitting reaction to overcome the bottleneck of the artificial photosynthesis, many groups have tried to synthesize the OEC in the laboratory since the 1990s. However, it was a great challenge for chemists to synthesize the whole structure of the OEC due to several reasons [38,91] including: i) It is very difficult to incorporate Ca 2+ into the Mn 4 -cluster through µ-oxo bridges because the affinity of Ca 2+ to µ-oxo is significantly weaker than that of the Mn ion. In general, only a homometallic cluster, instead of the heterometallic manganese-calcium cluster, can be isolated.…”

Artificial Mn4-oxido complexes mimic the oxygen-evolving center in photosynthesis

“…The water-splitting reaction catalyzed by the oxygen-evolving center (OEC) in photosystem II (PSII) of higher plants, alga and cyanobacteria forming oxygen, electrons and protons is one of the most important reactions on the earth [1][2][3]. Due to its significantly fundamental interests and potential applications, the investigation of the OEC has attracted extensive attention during the last two decades.…”