Professor Dolphin's research into bioorganic and bioinorganic chemistry revolves around macrocyclic systems such as porphyrins and vitamin B12. In these areas Professor Dolphin's group was the first to show that the redox chemistry of the porphyrin ring as well as the redox chemistry of the metal coordinated by porphyrin is important in biochemical processes. They have shown that in both photosynthesis and in a number of enzymatic reactions mediated by heme proteins, oxidation of the macrocyclic rings to a pi-cation radical is the critical step in the enzymatic functioning of these systems. Current studies include a determination of the mechanisms of action of cytochrome P-450 and the syntheses of numerous covalent ly linked dimeric porphyrins. For the future these dimeric porphyrins, when appropriately metallated, will be used to generate robust and inexpensive electrodes for fuel cells, catalysts for the reduction (electro-chemical) of nitrogen to ammonia and a system for the conversion of photonic energy into hydrogen and oxygen via the splitting of water.
Ligninase, the enzyme(s) that degrade lignin (which constitutes 25% of the world's total biomass), have recently been isolated and found to be heme proteins. Dr. Dolphin's research group has recently prepared simple chemical mimics of these enzymes, which show considerable promise in various aspects of the pulp and paper industry and that also have potential for the chemical degradation of environmental pollutants such as chlorinated hydrocarbons and phenols.
Porphyrin derivatives are being prepared which either by themselves or conjugated to antibodies can be used to kill cancer cells, in which they accumulate, by shining visible light on the tumor, whereu pon the porphyrin generates toxic singlet oxygen and kills the cell. These and many other aspects of photodynamic therapies are being studied.