Source: Dissertation Abstracts International, Volume: 69-06, Section: B, page: 3575.

Advisers: Gary W. Brudvig; Robert H. Crabtree.

Green plants and cyanobacteria possess the four manganese single calcium cluster necessary to oxidize water to O2. The photosynthetic process by which four flashes of light and two water molecules are transformed into O2 and a proton gradient is one of the most interesting and challenging in nature. We, along with many others, work to better understand the first step in photosynthesis by mimicking it with small molecules.

We attempt to understand the mechanism for oxidizing water by single electron steps through the use of electrochemistry. This study has demonstrated the necessity of proton coupled electron transfer (PCET) in the mechanism of water oxidation as well as shown how the coordination of simple ligands can have a great effect upon the reduction potential of high valent intermediates. The electrochemical studies shown here will hopefully lead to the first catalytic oxidation of water with a manganese catalyst using one electron oxidants.

In this thesis, we also detail the development of TiO2 based photochemistry capable of oxidizing manganese complexes. Manganese model chemistry is very close to oxidizing water through discrete one electron steps, but to truly mimic the natural system, we must carry out oxidation with light. The new photochemical system shown in this thesis details the mechanism involved in oxidizing a manganese complex immobilized on a semiconductor surface using visible light.