Ortho-Phenylenes have been found to take on conformations similar to those found in biological secondary structures, classifying them as a type of molecule known as foldamers. The goal of studying this class of molecules is to eventually use this simple structure in 3D molecules that mimic biological systems. Past studies have been done to investigate folding behavior in different substituent and solvent environments. This study expanded upon this knowledge by computationally studying the physical properties, as well as the proton and fluorine NMR shielding constants, for ortho-phenylene oligomers with fluorine atoms attached. Computations were done using Gaussian 16, and the computed shielding constants were compared with experimental data to perform conformational analysis. Overall, the tri- and hexa-fluorinated ortho-phenylenes displayed good folding behavior, with 88% and 97% of the respective mixtures containing the desired perfectly helical conformation. Comparing the computational results to the experimental results also revealed that proton and fluorine NMR are both effective methods for performing conformational analysis, allowing researchers to use more simple fluorine NMR spectra when the proton NMR spectra may be unclear. Overall, the information we learned about the folding behavior of fluorinated ortho-phenylenes, and the utility of fluorine NMR that was displayed by these results can be used to influence future studies to expand our knowledge of this class of foldamer molecules.
Author: Kaitlyn Flynn
Faculty Advisor: Scott Hartley, Chemistry and Biochemistry
Graduate Student Advisor: Viraj Kirinda, Chemistry and Biochemistry
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