Abstract:

This thesis defense is composed of two main parts. The first half discusses my efforts to investigate the selectivity and motion of individual molecular catalysts in polymer networks through the use of single-molecule fluorescence microscopy. The second half discusses my chemical education research for the transition of existing curriculum to Argument-Driven Inquiry.

Superresolution fluorescence microscopy provides a powerful tool to investigate mechanistic questions and reaction dynamics that would otherwise be resolution- or diffraction-limited, providing insight at the nanometer level. The first half of this thesis defense focuses on the motion of single molecular ruthenium catalysts during and after single turnover events of ring-opening metathesis polymerization as imaged through single-molecule superresolution tracking with positional accuracy of ±32 nm. This tracking is achieved through real-time incorporation of spectrally tagged monomer units into active polymer chains ends during living polymerization; thus, by design, only active-catalyst motion is detected and imaged, without convolution by inactive catalysts. The catalysts show diverse individualistic diffusive behaviors with respect to time that persist for up to 20 s. Such differential motion indicates widely different local catalyst microenvironments during catalytic turnover. These mobility differences are uniquely observable through single-catalyst microscopy and are not measurable through traditional ensemble analytical techniques for characterizing the behavior of molecular catalysts, such as NMR spectroscopy.

Traditional laboratory classes are often administered through “cookbook” style curriculum that does not accurately reflect the scientific inquiry and debate. To reflect this more realistic picture of the scientific process, the traditional curriculum of confirmation labs for the lower division undergraduate labs at University of California, Irvine has been adapted to Argument-Driven Inquiry, a guided inquiry curriculum that allows for debate and revision. In the second half of this thesis defense, I will describe the creation of a second quarter of a two-quarter sequence of argument-driven-inquiry general chemistry laboratories and outlines the ongoing effort to design a series of Organic Chemistry experiments to be used in an ADI course, with a focus on designing intentional variation to lead to robust argumentation.