the complexes of mn(oac)3 and/or mn(acac)3 with nucleic bases and nucleosides (adenine, guanine, xanthine, adenosine and guanosine) have been synthesized in nonaqueous solution. polarographic and spectroscopic (ir and visible) methods have been used to establish the active site(s) on the imidazole and pyrimidine rings in the nucleic bases and nucleosides for the interaction with the mn(iii) com...

Oxygen conversion process between O₂ and H₂O by means of electrochemistry or photochemistry has lately received a great deal of attention. Cobalt-phosphate (Co-Pi) catalyst is a new type of cost-effective artificial oxygen-evolving complex (OEC) with amorphous features during photosynthesis. However, can such Co-Pi OEC also act as oxygen reduction reaction (ORR) catalyst in electrochemical proc...

Photosynthesis uses light energy to drive the oxidation of water at an oxygen-evolving catalytic site within photosystem II (PSII). We report the structure of PSII of the cyanobacterium Thermosynechococcus elongatus at 3.5 angstrom resolution. We have assigned most of the amino acid residues of this 650-kilodalton dimeric multisubunit complex and refined the structure to reveal its molecular ar...

The Cover Feature shows the synthesizing mechanism of artificial Mn4Ca-cluster, a close mimic photosynthetic oxygen-evolving center (OEC). It is great challenge and long-standing issue to reveal Mn4Ca-cluster in both natural photosynthesis. New results shed light on OEC rational design water-splitting catalysts. More information can be found Research Article by C. Chen, B. Xu, et al.

In photosynthesis, photosystem II evolves oxygen from water by the accumulation of photooxidizing equivalents at the oxygen-evolving complex (OEC). The OEC is a Mn4CaO5 cluster, and its sequentially oxidized states are termed the Sn states. The dark-stable state is S1, and oxygen is released during the transition from S3 to S0. In this study, a laser flash induces the S1 to S2 transition, which...

The S1 → S2 transition of the oxygen-evolving complex (OEC) of photosystem II does not involve the transfer of a proton to the lumen and occurs at cryogenic temperatures. Therefore, it is commonly thought to involve only Mn oxidation without any significant change in the structure of the OEC. Here, we analyze structural changes upon the S1 → S2 transition, as revealed by quantum mechanics/molec...

T o convert the energy of sunlight into chemical energy, the leaf splits water via the photosynthetic process to produce molecular oxygen and hydrogen, which is in a form of separated protons and electrons. The primary steps of natural photosynthesis involve the absorption of sunlight and its conversion into spatially separated electron hole pairs. The holes of this wireless current are capture...

The complexes of Mn(OAc)3 and/or Mn(acac)3 with nucleic bases and nucleosides (adenine, guanine, xanthine, adenosine and guanosine) have been synthesized in nonaqueous solution. Polarographic and spectroscopic (IR and Visible) methods have been used to establish the active site(s) on the imidazole and pyrimidine rings in the nucleic bases and nucleosides for the intera...

Ammonia binds to two sites in the oxygen-evolving complex (OEC) of Photosystem II (PSII). The first is as a terminal ligand to Mn in the S2 state, and the second is at a site outside the OEC that is competitive with chloride. Binding of ammonia in this latter secondary site results in the S2 state S = (5)/2 spin isomer being favored over the S = (1)/2 spin isomer. Using electron paramagnetic re...

Synthetic access has been achieved into high oxidation state Mn/Ca chemistry with the 4 : 1 Mn : Ca stoichiometry of the oxygen-evolving complex (OEC) of plants and cyanobacteria; the anion of (Et(3)NH)(2)[Mn(III)(4)Ca(O(2)CPh)(4)(shi)(4)] has a square pyramidal metal topology and an S = 0 ground state.