Post-Synthetic Modification of Macromolecules via Photoredox Catalysis

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With this award, the Chemical Synthesis Program of the NSF Division of Chemistry is supporting the research of Professor Gary A. Molander of the Department of Chemistry at the University of Pennsylvania to develop new ways to modify macromolecules. Macromolecules are made up of a large number of atoms that are organized into building block subunits. Biological examples include proteins and enzymes (made of amino acid subunits), and DNA (formed from nucleotide subunits). Non-natural examples of macromolecules include carbon-based nanostructures used in photovoltaics and transistor materials, as well as metal-organic frameworks used as catalysts and drug-delivery systems. To efficiently create macromolecular materials for a diverse range of applications, it is necessary to modify macromolecules without disturbing their core structure and to do so in a manner that places the added groups in precise locations along the macromolecular backbone. Professor Molander and his research group are designing ways to use light as the sole energy source to activate catalysts that can be used to modify biomolecules, carbon-based nanostructures, and metal organic frameworks selectively and efficiently. The projects impact economic growth and quality of life through collaboration with a cohort of pharmaceutical and agrochemical companies to speed innovation and bring goods to market under more sustainable and environmentally benign conditions. The students involved in the project are trained and provided with industry-relevant research experience through collaborations with industrial partners.New photoredox processes are being developed as enabling reactions to modify a variety of important macromolecules post-synthetically. The macromolecular targets for these transformations include biomolecules, metal-organic frameworks, and carbon-based nanostructures (graphene, carbon nanotubes, and fullerenes). The focus of these efforts centers on the use of photoredox catalysis and photoredox/transition metal dual catalysis to allow unprecedented transformations to be conducted under extremely mild conditions, providing access to modified materials in a straightforward manner. Thus, the research is unlocking a virtually unlimited range of modifications that can be made on these materials, allowing practitioners in diverse fields of science to custom-design structural variants of their target molecules for any applications that might be envisioned. The protocols being developed allow these transformations to be carried out at room temperature in a matter of minutes to hours, permitting them to be utilized in any laboratory setting. The implementation of this technology is providing a significant impact to diverse areas of science, including biotechnology, energy research, and material science. The translational nature of the synthetic project is also providing important training experiences to the next generation of synthetic chemists.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.