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Abstract
This thesis outlines the synthesis and characterization of new asymmetrically substituted thiazolo[5,4-d]thiazole (TTz) compounds. This class of compounds contains a central bicyclic heteroaromatic system that is electron-deficient, and when substituted asymmetrically with both electron-donating and withdrawing groups, shows strong solvatofluorochromism. These asymmetric TTz compounds typically have very strong excited-state dipole moments and exhibit a "push-pull" electronic effect when photoexcited. These compounds also demonstrate sensitivity to their chemical environments and are interesting target compounds for various molecular sensing applications for this reason. A variety of synthetic routes have been pursued to access addition push-pull compounds containing amino, nitro, and acetamido functional groups. In particular, introducing primary amine functionality to asymmetrically substituted TTz compounds was a major synthetic focus of the research described in this thesis. These new TTz compounds show new and interesting photophysical properties. One of these synthetic routes has also provided a significantly more efficient way of yielding an asymmetric TTz compounds with these functionalities. The synthetic efforts as well as the optoelectronic properties of these new TTz materials will be presented. In particular, this class of compounds was being investigated for use as a fluorescent probe to study the antibacterial target enzyme undecaprenyl pyrophosphate synthase (UppS). Similar fluorophores have been used in the past, but the push-pull electronic nature of these compounds typically results in solvatofluorochromism, and the shift in fluorescence is often quite sensitive to the chemical environment of the TTz. For these reasons, this class of compounds is being investigated not only for the UppS application, but for general use as molecular sensors as well. The synthetic efforts toward developing, and photophysical properties of, TTz derivatives with amine, nitro, and acetamido functionalities will be described in this thesis.