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The four‐electron oxidation of water to form O2in photosynthesis is a light‐driven process that occurs in the multi‐subunit membrane protein Photosystem II (PSII). The reaction is catalyzed by an inorganic cluster known as the Oxygen Evolving Complex (OEC), which has a composition of Mn4OxCaCly.[1]A preliminary X‐ray crystal structure of PSII has recently been determined,[2]but the nature of the ligands bound to the manganese ions and the internal structure of the core were not fully revealed. Insight into the structure of the OEC has been gained primarily through X‐ray absorption spectroscopy (XAS) and spin resonance techniques (EPR/ENDOR) (reviewed in [3]). Based on these data, a number of candidate structures for the Mn4Oxsubcore were described, of which the two leading candidates are the Mn4O4‐funnel and the Mn4O4/Mn4O2‐butterfly subcores (Figure 1).

Neutral manganese(III) complexes have been prepared, with high yield and purity, by a modification of the Boucher synthesis, using asymmetrical Schiff base ligands. These ligands [H3-amsal = 3-aza-4-(2-hydroxyphenyl)-N-(2-hydroxyphenyl)but-3-enamide], mcorpo-rating hard donor atoms, are derived from the condensation of an amine precursor containing an amide group and substituted salicylaldehydes. The complexes are found to be of the form MnIII (amsal-R)(H2O)n (n=0.5,3) and have been characterised by various methods. Data point to octahedral geometry at the manganese atom.

Four samples of SO2 adducts in ethanol or toluene solutions, CuCl2(2,6-MepyO)2-(SO2)0.5(H2O)2, CuBr2(3-HOH2CpyO)2(SO2)0.5, MnI2(4-MepyO)2(SO2)0.75(H2O)4 and CoI2(4-CNpyO)2(SO2)0.75(H2O)2, were exposed to air at room temperature by simply exposing them to air for about a month or by bubbling air into the solution for 4h and subsequent stirring for 12h. After this procedure, oxidation products and ligand derivatives, obtained from adducts where S02 bridged between two metal centres, were isolated and characterised. Thus, the aerobic oxidation of MnI2(4-MepyO)2(S02)0.75(H20)4 and CoI2(4-CNpyO)2(S02)0.75(H20)2, respectively, yield the decomposition products [(4-MepyO)2H](I3) and [Co(4-EtO2CpyO)6](I8), which have been crystallographically characterised. Furthermore, we have isolated and clearly identified blue crystals of CuS04 5H20 from solutions of both CuCl2(2,6-MepyO)2-(SO2)0.5(H2O)2 and CuBr2(3-HO2HCpyO)2(SO2)0.5.

AbstractAdducts of accurate formula MX2(2,6-MepyO)2(H2O)n (M = Mn, Cu; 2,6-MepyO = 2,6-dimethylpyridine N-oxide; X = CI, Br, I and NO3; n = 0, 2, 3, 6) react with SO2in the solid state and in toluene slurries at room temperature to yield SO2adducts of different stoichiometry The medium of the reaction influences the ability of the adducts to bind sulphur dioxide and which usually can retain a greater quantity of SO2in toluene slurries than in the solid state. An increase in the temperature disfavours the reaction in the solid state. Desorption studies were performed in order to postulate a coordination mode for the bound sulphur dioxide. This study, as well as analytical and spectroscopic data, allow us to suggest that the SO2is bridging between metal centres andor is bound to the neutral ligand (mean) in most of the SO2adducts.

AbstractA series of unsymmetrical tridentate dianionic Schiff bases derived from substituted salicylaldehyde and ethanol and propanolamine were prepared and characterised by elemental analyses, IR and 1H NMR spectroscopy. The interaction of these bases with Mn(ClO4)2.6H2O has been studied, leading to the preparation of manganese(III) perchlorate complexes. All the Schiff base ligands H2L yield 1:1 compounds [MnL(H2O)2]CIO4.nH2O (n = 1–3). The resultant complexes were characterised by elemental analyses, IR spectroscopy and magnetic measurements.Referee I: L. T. BoucherReferee II: J. H. Worrell

El artículo proporciona información sobre un caso de degeneración walleriana. La degeneración walleriana se caracteriza por una degeneración secundaria de las fibras descendentes, posiblemente debido a lesiones corticales o subcorticales producidas por infartos, hemorragias o neoplasias. En este caso, los cambios de degeneracion eran visibles en la DW y en T2 y FLAIR.

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Competing Interests: The authors declare the following competing financial interest(s): EWT is a Director and shareholder of Myricx Pharma Ltd.