Tuning the Thermodynamics and Kinetics of H+ and e- Transfer in Nanoconfined Environments

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With the support of the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry, Dr. Mark Lipke of Rutgers, The State University of New Jersey will design and study the chemical properties of hollow molecular cages. This project aims to provide detailed insights into how the acidity and electron-transfer properties of chemical species are altered when confined in nanometer-sized cavities. This fundamental knowledge is important for the development of chemical processes and catalytic materials for applications in advanced manufacturing. Alongside these efforts, the PI and his students will give talks at local high schools to illustrate how high school level chemical concepts are useful in cutting edge research. Dr. Lipke will also provide research internships for high school students and will develop new teaching materials for undergraduate courses.This research will be carried out using modular porphyrin nanocages that provide control over solvation and noncovalent interactions in nanoconfined environments to probe how these variables influence the thermodynamics and kinetics of H+ and e− transfer processes, including proton-coupled electron transfer (PCET) processes that are essential to many electrochemical transformations. This work has three aims. Aim I will develop robust, redox-active nanocages of different sizes, shapes, and H-bonding abilities that are well-suited to systematic chemical and electrochemical studies. Aim II will systematically measure how the pKa values and reduction potentials of encapsulated guests are affected by low relative permittivity nanocavities. Aim III will examine how the kinetics of H+ and e– transport to guest molecules bound in the nanocages can be controlled. The nanocages that will be employed in these studies can be characterized in both solution and the solid state, enabling detailed solution-phase mechanistic experiments to be performed on nanoporous structures that can be characterized with atomic resolution in the solid state. This research will make significant contributions to the mechanistic understanding of H+ and e− transfer processes in nanoconfined spaces, which in turn, will be useful for informing the rational design of porous structures with tunable properties for these important chemical processes.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.