Oxidation Chemistry: Chemistry of Reactive Oxygen Species with Organometallic Compounds and some Heteroatoms

The Selke group uses a variety of methods (time-resolved spectroscopy, steady-state kinetics, as well as preparative methods) to study the chemistry of reactive oxygen species (especially singlet dioxygen). This area is of interest in biology as well as catalyses.

 Light and oxygen can be toxic. Cell constituents or certain chemicals found in the environment (some plant pigments, flavins etc.) absorb light and subsequently interact with oxygen molecules causing the latter to become more reactive. This process is called sensitization. The oxygen may then react with DNA constituents, amino acids, and, probably, with some amino acids coordinated to metals found in enzymes. This process may damage or destroy the enzyme. On the other hand, the same process is used in tumor phototherapy, where tumor cells are killed as described above. Understanding the chemistry of this process may therefore be of medicinal importance. One of the oxygen species produced during the sensitization process is singlet oxygen. Reactions of singlet oxygen with biomolecules have been studied for several decades, but its chemistry with organometallic compounds and heteroatoms has received far less attention.

The major research focus of our group is the exploration of the chemistry of singlet oxygen with organometallic compounds and compounds containing heteroatoms such as phosphorus and sulfur. The basic aims are threefold: (i) To solve a number of fundamental mechanistic questions in oxidation chemistry, (ii) to find new oxidants derived from the most benign oxidant, i.e. dioxygen, and (iii) to develop new photosensitizers for the production of singlet oxygen with potential biomedical applications. 

Reactive intermediates in oxygen chemistry are often difficult to detect because they themselves are powerful oxidants. We are trying to find new methods (using singlet dioxygen) to observe and possibly isolate such species and, where applicable, to investigate their potential as oxidants. We are also exploring the susceptibility of metal-bound amino acids (especially cysteine) toward oxidation by singlet oxygen.