Metalloporphyrin-Based Catalytic Systems and Functional Materials.
The primary research interests of our group are in the areas of organic and organometallic chemistry. The research program involves the design and synthesis of new organic and organometallic compounds, and the exploration of their applications in areas of catalysis, medicine, biomimics and materials. Current research projects center on the synthesis of functional porphyrins including chiral porphyrins and their applications in the following fields: 1) Development of catalytic systems for selective chemical reactions, especially for asymmetric organic synthesis; 2) Discovery of new diagnostic and therapeutic agents for diseases such as cancer and neurodegenerative diseases; 3) Construction of functional models for enzymatic systems that can mediate important chemical and energy transformations; and 4) Synthesis of novel functional materials such as metal-organic frameworks for hydrogen storage and solar energy conversion.
Biological systems are capable of mediating many important chemical and energy transformations that are challenging problems in non-biological systems. Our approach in developing new catalytic systems for asymmetric organic synthesis is inspired by the extraordinary versatility and capability of heme and related enzymes. We are interested in designing and constructing metalloporphyrin-based artificial enzymes to catalyze selective chemical transformations. Current efforts include the development of efficient catalytic systems for asymmetric atom/group transfer reactions, including epoxidation, aziridination and cyclopropanation of alkenes as well as hydroxylation, amination and carbene insertion of C–H bonds. These catalytic synthetic methods will allow us to selectively convert inexpensive and abundant hydrocarbons into value-added functional molecules such as chiral compounds that have potential applications in medicine and materials. One of other significant examples from Mother Nature is the photosynthetic organism that can efficiently convert solar energy into chemical energy. The first event of this vital process takes place in light-harvesting complexes, which are around the reaction center complex. The structures of the light-harvesting complexes have been determined by X-ray crystallography and revealed breathtakingly beautiful marcrorings that consist of multiple bacteriochlorophyll-a units in a well-organized fashion. We are interested in mimicking the light-harvesting antenna through construction of multiple porphyrin arrays for solar energy application, due to the close structural relationship between bacteriochlorophylls and porphyrins. Among several approaches, the non-covalent approach starts with the synthesis of porphyrins that contain metal coordination units in the periphery. These functionalized porphyrins are then self-assembled through metal coordination to form metal-porphyrin frameworks (MPFs). In addition to solar energy conversion, MPFs have been also targeted for application as hydrogen storage materials.