Chemistry Department Seminar

The rapid consumption of fossil fuel has caused unacceptable environmental problems such as green house effects, which would lead to disastrous climatic consequences. Thus, renewable and clean energy resources are definitely required in order to solve global energy and environmental issues: Since nature harnesses solar energy for its production by photosynthesis, why not imitate nature to create artificial photocatalytic electron-transfer systems that exploit the basic chemistry of photosynthesis in order to produce hydrogen or other fuels? The specific objective of this lecture is therefore to describe recent development of bioinspired electron-transfer systems including artificial photosynthesis and respiration together with their applications.
First, multi-step electron-transfer systems composed of electron donor-acceptor ensembles have been developed, mimicking functions of the photosynthetic reaction center.2'3 However, a significant amount of energy is lost during the multi-step electron-transfer processes. Then, as an alternative to conventional charge-separation functional molecular models based on multi-step long-range electron transfer within redox cascades, simple donor-acceptor dyads have been developed to attain a long-lived and high energy charge-separated state without significant loss of excitation energy.4-7 Such simple molecular dyads, capable of fast charge separation but extremely slow charge recombination, have significant advantages with regard to synthetic feasibility, providing a variety of applications including construction of organic solar cells and development of efficient photocatalytic systems for the, solar energy conversion.8-11
On the other hand, the four-electron reduction of 02 is not only of great biological interest, but also of technological significance such as fuel cells. Thus, recent development of efficient electron-transfer catalytic systems for four-electron reduction of 02 is also presented and the catalytic mechan