Overview   |   Catalytic Synthesis   |   Biomimetic Design   |   Functional Biomaterial
Catalytic Synthesis of Macromolecules

We are developing atom economic synthetic methods for constructing complex and functional macromolecules from simple building blocks. A key aspect of this project is the discovery of new transition metal catalysts, which involves design and synthesis of novel organic ligands and organometallic complexes, investigation of their reaction kinetics and mechanisms, and finally studies of their catalytic polymerization properties. For example, we have developed a series of cyclophane alfa-diimine-based Ni(II) and Pd(II) complexes that show excellent catalytic properties. Recently we have introduced a hemilabile donor group that can reversibly interact with the axial site of the metal center to modulate the catalytic behavior. A number of novel complexes are currently investigated as potential catalysts for efficient synthesis of functional polyolefins and polyamides.

Using these efficient catalytic methods, we are constructing complex and functional macromolecules from readily available monomers. For example, via chain walking polymerization using palladium catalysts, we have developed one-pot synthesis of globular dendritic macromolecules from simple and abundant olefins and functional olefins. These molecular architectures, including core-shell unimolecular micelles and organic nanoparticles, are explored as nanocarriers for drug delivery and as nano-scaffolds for multivalent bioconjugation. Recently, we are developing efficient catalytic synthesis of functional polyamides through direct polymerization of sustainable natural monomers such as amino acids and saccharides. These polyamides are currently investigated as biomaterials for gene delivery and tissue regeneration applications.
 
Representative publications:
1.
A Mechanistic Investigation of the Unusually Efficient Copolymerization Behavior with Polar Olefins for the Cyclophane-α-Diimine Based Pd (II) Catalys. Popeney, C.; Guan, Z. J. Am. Chem. Soc. 2009, 131, 12384-12389.
2.
Axial Coordinating Ligands: a New Strategy for Late Transition Metal Olefin Polymerization Catalysis. Leung, D.; Ziller, J. W.; Guan, Z. J. Am. Chem. Soc. 2008, 130, 7538-7539.
3.
Tandem Chain Walking Polymerization and ATRP for Efficient Synthesis of Dendritic Nanoparticles for Protein conjugation. Chen, G.; Huynh, D.; Felgner, P. L. and Guan, Z. J. Am. Chem. Soc. 2006, 128, 4298-4302.
4.
A General Strategy for Nanoparticle Dispersion. Mackay, M. E.; Tuteja, A.; Duxbury, P. M.; Hawker, C. J.; Van Horn, B.; Guan, Z.; Chen, G.; Krishnan, R.S. Science 2006, 311, 1740-1743.
5.
Cyclophane-Based Highly Active Late-Transition-Metal Catalysts for Ethylene Polymerization. Camacho, D.; Salo, E. V.; Ziller, J. W.; Guan, Z. Angew. Chem. Int. Ed. 2004, 43, 1821-1825.
 
This project is supported by :
National Science Foundation (Division of Chemistry, Division of Materials Research-Polymer)