Ultrafast Time-Resolved Spectroscopy Probes Carboxylate Metal Binding and Proton Transfer Kinetics in Condensed PhaseMitra, Sunayana (2021) Ultrafast Time-Resolved Spectroscopy Probes Carboxylate Metal Binding and Proton Transfer Kinetics in Condensed Phase. Doctoral Dissertation, University of Pittsburgh. (Unpublished) This is the latest version of this item.
AbstractThis dissertation describes two scientific experimental techniques, namely two-dimensional infrared (2D-IR) spectroscopy and time–resolved multiprobe spectroscopy. These methods probe metal coordination geometry in multi-carboxylates and proton transfer kinetics in protic ionic liquids, respectively. Another aspect of this dissertation discusses making the scientific literature accessible to students early in their undergraduate careers. For the metal–carboxylate structural investigation, symmetric stretch vibrational peaks were probed using the EDTA molecule and divalent Ca2+ and Mg2+ ions. Multi–carboxylates are components of proteins. The carboxylate symmetric stretching vibration is sensitive to metal–induced structural changes. In EDTA’s carboxylate stretching region, the symmetric stretch mixes with the CH bending modes. With 2D-IR spectroscopy, density functional theory, participation coefficient analysis, and energy decomposition analysis calculations, the different vibrational contributions were disentangled and associated with the ion binding geometry. Hence, the ion–binding information from EDTA’s symmetric stretch region can be utilized in protein–ion binding research. In the second investigation, time-resolved multiprobe spectroscopy probed a photoacid dissolved in a protic ionic liquid to unravel the proton transfer kinetics in an ionic liquid environment. Our investigation with this system suggests that proton transport has fast kinetics falling within the Grotthuss mechanism and slow rates that match vehicular transport. The time-resolved multiprobe spectroscopy data, ranging from a few hundred femtoseconds to several nanoseconds, reflect the complicated kinetic pathway of the proton in such a system. This work indicates that protic ionic liquids have complex reaction kinetics that must be modeled using the proton conduction models for water. Thirdly, this document describes a curriculum that helps undergraduates assess the research presented in scientific literature. The first semester of this curriculum teaches students to read and comprehend existing original research literature. With worksheet assignments, workshops, and office hours, the students interpret hypotheses, experimental methods, conclusions, and future directions in research. This curriculum provides undergraduates a starting Share
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