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The molecular oxygen produced in photosynthesis is generated via water oxidation at a manganese–calcium cluster called the oxygen-evolving complex (OEC). While studies in biophysics, biochemistry, and structural and molecular biology are well known to provide deeper insight into the structure and workings of this system, it is often less appreciated that biomimetic modelling provides the foundation for interpreting photosynthetic reactions. The synthesis and characterization of small model complexes, which either mimic structural features of the OEC or are capable of providing insight into the mechanism of O2 evolution, have become a vital contributor to this scientific field. Our group has contributed to these findings in recent years through synthesis of model complexes, spectroscopic characterization of these systems and probing the reactivity in the context of water oxidation. In this article we describe how models have made significant contributions ranging from understanding the structure of the water-oxidation centre (e.g. contributions to defining a tetrameric Mn3Ca-cluster with a dangler Mn) to the ability to discriminate between different mechanistic proposals (e.g. showing that the Babcock scheme for water oxidation is unlikely). [ABSTRACT FROM AUTHOR]

The use of di-2-pyridyl ketone oxime (Hpko)/X−“blends” (X− = OH−, Cl−, ClO4−) in copper chemistry has yielded neutral binuclear and cationic trinuclear, pentanuclear or hexanuclear complexes. Various synthetic procedures have led to the synthesis of compounds [Cu5(pko)7]·[ClO4]3·2CH3OH·2H2O (1), [Cu3(pko)3(OH)(Cl)]2[Ph4B]2·4DMF·2H2O (2), [Cu2(pko)4] (3), {[Cu6(pko)6ClO4(CH3CN)6][Cu6(pko)6(ClO4)3(CH3CN)4]}·8ClO4·14CH3CN·H2O (4). The structures of the complexes have been determined by single-crystal X-ray crystallography. [ABSTRACT FROM AUTHOR]