CAS: Near-Infrared Light Control of Metal Catalyzed Reactions and Polymerizations

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With the support of the Chemical Catalysis program in the Division of Chemistry, Professor Tomislav Rovis of Columbia University is studying the use of near-infrared (NIR) light to control catalysts that mediate a number of fundamental chemical reactions. Catalysis is a technology of prime importance and has deep implications in many fields, ranging from synthetic chemistry to the production and manufacturing of pharmaceuticals, fine and commodity materials, as well as new well-defined materials. Indeed, it is estimated that 85% of all products made involve catalysis at some point in their production. Most work on the development of new catalytic systems focus on aspects related to efficiency and selectivity. The notion of spatial and temporal control has been largely under-studied and remains elusive. Of all possible stimuli to achieve control, light is the most attractive since it is noninvasive, it can be easily manipulated thanks to modern optics techniques. NIR light is particularly suitable as it can penetrate materials and induce reactions through barriers. This can be attractive to the plastics industry, as it allows the shaping of highly controllable yet robust materials through molds. The project will establish the use of NIR light to control polymerizations through material barriers with an eye towards achieving new technological breakthroughs to enable, enhance, and drive plastics and material science. The project will also create the opportunity to synthesize a set of industrially recyclable, environmentally benign polymers from which the monomer can be regenerated and reused. Additionally, educational opportunities will be provided for underrepresented students, from elementary school students to undergraduates, to broaden interest and educate them in photochemistry and polymerization. With the support of the Chemical Catalysis program in the Division of Chemistry, Professor Tomislav Rovis of Columbia University is studying the use of near-infrared (NIR) light to activate various catalysts to effect catalyzed polymerizations through barriers. The project will establish NIR control of ruthenium-catalyzed olefin metathesis reactions for the spatiotemporal controlled synthesis of polyolefin-like structures. Inherent to the approach is the propensity of low-energy NIR light to penetrate material barriers such as silicone, paper, plastic and even tissue. The project aims to take maximum advantage of the energy of NIR light to induce chemical change at the catalyst of interest. This research has he potential to greatly enhance fundamental understanding of the mechanism of NIR-initiated olefin metathesis. Extensions of this work will include orthogonal light and heat polymerization and depolymerization along with in situ studies for bioimaging. With this approach, the project will also extend into other NIR-controlled polymerizations, including N-heterocyclic carbene activation to induce polymerization en route to polyurethanes and polyesters, two crucial families of organic materials. Finally, the project will establish a visible demonstration of NIR-enabled polymerizations that will be used to teach catalysis, central to so many facets of everyday life, to broaden awareness of fundamental science.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.