Collaborative Research: Photocatalytic Ketyl and Amino Radicals-Initiated C-C Bond Formation via Semiconductor-Based Photocatalysts

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The development of economic and efficient methods to form carbon-carbon bonds is an important role in the chemical industry. Many traditional strategies have been invented based on sophisticated molecules known as catalysts. A common and persisting limitation of known catalysts is that they are expensive, inefficient, and generate unwanted byproducts as waste. Following the principles of green chemistry Dr. Yujie Sun from University of Cincinnati and Dr. Peilin Liao from Purdue University, with funding from the Chemical Catalysis Program, are collaborating to design and develop improved catalysts for these important transformations. Their synergistic experimental and computational project is addressing the fundamental science needed to use light as the energy source to drive carbon-carbon bond forming reactions using photocatalysts. Dr. Sun is developing a new course in Green Chemistry to undergraduates a broad background of sustainability in the context of chemistry. The Sun group is also actively involved in many outreach programs at University of Cincinnati, including UC Community Day Open House, UC-Chem Summer Camp at Cincinnati Museum Center, Science Day at the UC Center for Field Studies for K-12 grade students and the general public. Dr. Liao’s group is involved in outreach programs at Purdue University, such as Purdue NanoDays and the Purdue Summer Undergraduate Research Fellowship Program.With funding from the Chemical Catalysis Program of the Division of Chemistry, Dr. Yujie Sun of the University of Cincinnati and Dr. Peilin Liao of Purdue University are developing a novel synthetic approach to C-C coupling reactions on semiconductor-based photocatalysts. Ultrathin semiconductor-based photocatalytic systems, including CdS, ZnIn2S4, and CNx nanosheets, are synthesized, characterized, and systematically investigated for the C-C coupling reactions of carbonyls, alcohols, amines, and imines under visible light irradiation. By modulating the morphology and band structures of targeted semiconductors and matching the redox potentials of organic substrates, ketyl and amino radicals are produced in proximity on the semiconductor surface, which readily couple to accomplish the desired C-C bond formation. It should be emphasized that this strategy utilizes both excited electrons and holes, maximizing the energy efficiency of photocatalysis and circumventing the necessity of sacrificial reagents. Assisted by DFT computations, this project encompasses solid-state synthesis, materials characterization, photolysis investigation, isotope and electronic effects study, and kinetic analysis, starting from model systems for homo-coupling to complex cross-coupling of a broad scope of substrates. Both Dr. Sun and Dr. Liao are actively engaged in STEM outreach programs focused on underrepresented students and the general public, in support of the broader impacts of this project.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.