Measuring the Time-Varying Charge on a Single Catalyst Molecule via Electrometry

University Of Wisconsin-Madison, Madison WI

Investigators

Abstract

With the support of the Chemical Measurement and Imaging Program in the Division of Chemistry, Professor Randall Goldsmith of the University of Wisconsin-Madison will develop a chemical measurement system capable of measuring the time-varying charge on a dynamic single organometallic molecule. The new system will be able to reveal nuances in charge and coordination environment, an unprecedented new single-molecule measurement capacity, and an exciting result that paves the way to monitoring the shifting structure of a single catalyst molecule. This research will provide new insights into catalyst mechanisms by providing a molecular movie, revealing mechanistic details leading to the discovery of future catalysts and ultimately contributing to the development of new materials, cheaper fuels, and more accessible pharmaceuticals. Graduate and undergraduate students will gain highly interdisciplinary experience by blending reaction mechanism with cutting-edge instrumentation science. Outreach activities will involve K-12 students, teachers, and the general public in observing fluorescence from plants, microplastics, and even smaller items like single molecules using a portable microscope system. This research effort will develop a radically new way to encode information into the fluorescence of a single catalyst molecule. The proposed work will use single-molecule electrometry in which arrays of patterned nanowells create shallow electrostatic traps for solution-phase molecules. The rate at which the molecules leave these traps will be a sensitive function of their total charge, allowing a snapshot determination of the complex’s charge. This snapshot determination will allow a new perspective on catalyst charge dynamics of unprecedented detail, with measured effective charges reporting on catalyst oxidation state, ligand environment, and solvation. Most importantly, the measurement technique can be applied to chemically dynamic operational catalysts, allowing the observation of changes to the effective charge throughout the catalytic cycle, a unique measurement capability. 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.