SusChEM: Metal Organic Nanoparticles (MONPs) for Supramolecularly Assisted Covalent Assembly

A wide range of important organic compounds, including pharmaceutical agents, are prepared from simpler, commercially available materials. The synthesis of these organic compounds often takes several steps, some of which involve metal-based catalysts. Developing catalysts that give higher yields and operate in water reduces both the amount of volatile organic solvents used and the heavy metal waste, thus, making these synthetic processes more sustainable. With the support from the Macromolecular, Supramolecular and Nanochemistry Program of the NSF Chemistry Division, Prof. Steven C. Zimmerman at the University of Illinois at Urbana-Champaign is developing nanoscale, polymer-based metal catalysts that can perform such reactions in water and, because of their low toxicity, even in human cells. Thus, a broader impact of the work is the creation of a nanoscale robot, a 'nanobot' that selectively enter certain types of cells and prepare bioactive agents from smaller, cell-permeable, but inactive small molecules. Another broader impact is the training of a diverse group of undergraduate and graduate students.

The research team at the University of Illinois is developing new polymeric catalysts, prepared by ring-opening metathesis polymerization, that expand the types of reactions performed. Optimized metal-organic polymeric nanoparticles (MONPs) are designed to catalyze the copper-assisted 'click' reaction, the palladium-catalyzed Suzuki-Miyaura coupling reaction, and the ruthenium-mediated ring-closing metathesis reaction. The hydrophobic interior of these MONPs is designed to allow the reactions to proceed in water at low concentrations of catalyst by taking advantage of the hydrophobic interior of the nanoparticles. Efforts are directed toward the preparation of MONPs that contain two different catalytic centers to allow sequential, orthogonal processes to occur, increasing the complexity and power of the MONP approach. Finally, an ONP that modularly binds metal catalysts using hydrophobic binding is being pursued as a more universal, plug-and-play strategy.