In a previous detailed study of all the steps of water oxidation in photosystem II, it was surprisingly found that O2 release is as critical for the rate as O-O bond formation. A new mechanism for O2 release has now been found, which can be described as an opening followed by a closing of the interior of the oxygen evolving complex. A transition state for peroxide rotation forming a superoxide ...

Oxovanadium(IV), manganese(II) and copper(II) complexes of a Schiff base ligand derived from 2,4-dihydroxyacetophenone and 1,2-diaminocyclohexane have been encapsulated in the nanocavity of zeolite-Y by flexible ligand method and characterized by metal analysis, IR spectroscopic studies and X-ray diffraction patterns. The encapsulated complexes abbreviated here as CuL-Y, MnL-Y and VOL-Y catalyz...

The removal of Mn(II) from coal mine drainage (CMD) by chemical addition/active treatment can significantly increase treatment costs. Passive treatment for Mn removal involves promotion of biological oxidative precipitation of manganese oxides (MnOx). Manganese(II) removal was studied in three passive treatment systems in western Pennsylvania that differed based on their influent Mn(II) concent...

Structurally well-defined hetero-pentanuclear manganese-oxide clusters {MMn4} were successfully synthesized in TBA7Hn[MMn4(OH)2(A-α-SiW9O34)2]·2H2O·C2H4Cl2 (, M = Fe(iii), Co(ii), Ni(ii), Cu(ii), Ga(iii)) by sequential introduction of metal cations into the trivacant lacunary polyoxometalates (POMs). The pentanuclear manganese-oxide cluster {Mn5} showed a small spin ground state and a low energ...

A six-coordinate manganese (II) complex with the tripod ligand tris(2-benzimidazolylmethyl)amine (ntb), with composition [Mn(ntb) (4-hydroxycinnamate)](4-hydroxycinnamate) · (DMF)0.5 · (H2O)3, was synthesized and characterized by elemental and thermal analyses, electrical conductivity, IR, and UV/vis spectral measurements. The crystal structure of the complex has been determined by the single-c...

Visible-light-derived O(2) production was yielded by conjugating water oxidation catalysis by [(OH(2))(terpy)Mn(μ-O)(2)Mn(terpy)(OH(2))](3+) as an oxygen evolving center model and photo-sensitization of [Ru(bpy)(3)](2+) as a photoexcitation center model at an interlayer of mica.

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...