Office: Ekeley Science M343
Lab: Ekeley Science M376, M386
Lab Phone: 303-492-8954
Ph.D.: University of Illinois at Urbana-Champaign, 2005
Postdoctorate: Massachusetts Institute of Technology, 2006-2008
Organic, Nanotechnology/Materials, Renewable Energy
The research in my group is focused on the design and synthesis of novel organic functional materials targeting a broad range of environmental, energy and biological applications, such as gas separation/storage (e.g., carbon capture), hybrid nanocomposite fabrication, light harvesting, and nanomedicine. Our efforts in developing novel materials frequently lead us to explore new synthetic tools, particularly in the area of dynamic covalent chemistry (DCC) (e.g., metathesis reactions), which enable efficient materials synthesis.
In recent years, there has been intense interest in organic shape-persistent molecular architectures, including 2D macrocycles and 3D cages, which have been playing important roles in nanomaterials and nanotechnology development. Conventionally, these rigid molecules are mainly prepared via irreversible cross-coupling reactions, which are under kinetic control and usually provide very low yields of target compounds. Our group has successfully applied thermodynamically controlled, dynamic covalent chemistry (DCC) to the synthesis of various 2-D and 3-D molecules. In our approach, provided a large energy gap between the target species and other possible products, DCC is capable of generating the desired molecular architecture in high yield from readily available simple building blocks. DCC is one of the main synthetic tools in my group, and we are developing novel dynamic covalent reactions and catalysts that would enable fast reversible covalent bond formation.
Recently, organic porous materials have rapidly emerged as promising materials for gas storage/separation. These new materials are composed of only relatively light elements (e.g. C, H, B, N, O) that are connected by strong covalent bonds, offering great thermal and chemical stability. To date, preparation of these porous materials has generally focused on synthesizing amorphous organic polymers with non-ordered structures or densely packed polymers having crystalline structures. However, these approaches usually yield insoluble polymers, and solution-processable porous materials for certain applications (e.g., membrane fabrication for gas separation) have not yet been realized. In this project, we have explored well-defined, shape-persistent, 3-D organic molecules (prepared through highly efficient DCC) as soluble organic porous materials for gas adsorption and separation. Our group also developed "cage-to-framewok" strategy to construct novel organic porous materials using well-defined 3-D cages as building blocks. Our "cage-to-framework" strategy would enable efficient encoding of both dimensional (pore size/distribution) and functional information (guest recognition, sensing, catalysis, etc.) within the individual cage molecule into the final frameworks, enabling control over their pore size/distribution and chemical nature of the surface area.
Nanomedicine has been emerging as an active and promising research area with emphasis on exploiting the unique properties of nanomaterials for therapeutics and targeted drug delivery. In searching for nanocages that are compatible with biological systems, we discovered a subset of COPs that are fluorescent and enter mammalian cells efficiently. In this project, we aim to develop novel nanohybrid materials using 3D shape-persistent organic molecular cages that can potentially be translated clinically for non-invasive delivery of therapeutic agents, diagnostics imaging and testing the efficacy of targeted therapeutic agents in vitro and in vivo.
As the energy demand continues to grow and current existing fuel sources are non-renewable, efficiently converting solar energy into electricity and chemical fuels (e.g. H2) is highly desired. Tremendous research efforts have been devoted to the development of high-efficiency solar cells and artificial photosynthetic systems. We are interested in the following two areas in solar energy research: Developing organic or organometallic dye molecules with novel structural motifs for high-efficiency dye-sensitized solar cells (DSSCs); Utilizing carbon nanotubes (CNTs) and 3-D cages as the platform for modular construction of nanohybrid light harvesting systems. In both cases, the system efficiency will be optimized by varying the structure of each component through rational molecular design. The modular approach we are using would greatly facilitate the structure-activity relationship study and can provide critical knowledge for rational design of CNT-based photoactive composite materials.