Gerhard F. Swiegers

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Special CCB seminar presentation by Dr. Gerhard F. Swiegers, Intelligent Polymer Research Institute and ARC Centre of Excellence for Electromaterials Science, University of Wollongong, Wollongong, New South Wales, Australia.

See below for updated seminar title/abstract.

Seminar Title: "Catalytic solar water splitting inspired by photosynthesis: Homogeneous catalysts with a Mechanical ("Machine-like") action"

Abstract: Chemical reactions may be controlled by either: (1) the minimum threshold energy that must be overcome during collisions between reactant molecules/atoms (the Activation Energy, E_a), or: (2) the rate at which reactant collisions occur (the Collision Frequency, A) (for reactions with low E_a).  Reactions of type (2) are governed by the physical, mechanical interaction of the reactants.  Such mechanical processes are unusual, but not unknown in molecular catalysts.  We examine the catalytic action and macroscopic properties of several abiological mechanical catalysts and show that they display distinct similarities to machines - molecular machines in this case. They also display properties that are common with enzymes in general.  An abiological model of the Photosystem II Water Oxidizing Complex that appears to employ a mechanical action has now been found to be a remarkably active and sustained molecular catalyst of water oxidation when illuminated by sunlight. A free-standing water-splitting dye-sensitized solar cell has been built using this catalyst.  This cell is a functional and conceptual equivalent of the photosystem II water-oxidizing center in photosynthesis.