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 α-diimine-based Ni(II) and Pd(II) complexes that show excellent catalytic properties. Using these catalysts we have developed a one-pot synthesis of globular dendritic macromolecules from abundant olefins. Other molecular architectures, including core-shell unimolecular micelles and organic nanoparticles, are explored as nano-carriers for drug delivery and as nano-scaffolds for multivalent bioconjugation.

Recently our catalysis project has been focused on the investigation and development of new ruthenium-based complexes for materials synthesis. In one project, we have developed novel ruthenium complexes that are active for ethylene insertion polymerization. In another project, we developed the first direct polyamidation by catalytic dehydrogenation of diols and diamines. This method avoids the need of stoichiometric pre-activation or in situ activation reagents required for conventional polycondensation method and provides a greener process with high atom economy for polyamide synthesis. A number of novel ruthenium complexes are currently under investigation as potential catalysts for the efficient synthesis of both functional polyolefins and polyamides. Some of the functional materials can be used as biomaterials for gene delivery and tissue regeneration applications.

 
Representative publications:
1.
From Racemic Alcohols to Enantiopure Amines: Ru-Catalyzed Diastereoselective Amination. Oldenhuis, N. J.; Dong, V. M.; Guan, Z. J. Am. Chem. Soc. 2014, 136, 1254812551.
2.
Ruthenium(IV) Complexes for Ethylene Insertion Polymerization. Friedberger, T.; Ziller, J. W.; Guan, Z. Organometallics 2014, 33, 1913-1916.
3.
Direct Observation of a Cationic Ruthenium Complex For Ethylene Insertion Polymerization. Camacho-Fernandez, M. A.; Yen, M.; Ziller, J. W.; Guan, Z. Chem. Sci. 2013, 4, 2902-2906.
4.
Direct Synthesis of Polyamides via Catalytic Dehydrogenation of Diols and Diamine. Zeng, H.; Guan, Z. J. Am. Chem. Soc. 2011, 133, 1159-1161.
5.
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.
6.
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.
7.
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.
8.
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.