![]() Around this time, our lab began a collaboration with Dr. The above work opened many questions about why C8S3 organizes into highly-ordered superradiant J-aggregates while other cyanine dyes fall short. To better understand those changes in superradiance, we employed a computational screening that unraveled a correlation between tube radius and disorder. While the new aggregates were considerably redshifted, they displayed different kinetics of aggregation, ultimately leading to stabilization of a morphology with decreased superradiance. ![]() This work begins with synthesis of penta- and heptamethine derivatives of C8S3, followed by a careful screening of their J-aggregation via absorbance and cryo-electron microscopy (cryo-EM), and lastly a thorough spectroscopic characterization of each aggregate’s emissive properties. By elongating the polymethine chain of a well-studied cyanine dye (colloquially known as C8S3), I demonstrate the formation of tubular aggregates in the near-infrared regime. Chapter one contains a historical perspective on cyanine dyes and aggregates as colorants, as well as a short literature survey of how a dye’s structure determines the optical properties of its resulting J-aggregates.In chapter two, I explore the design of superradiant J-aggregates in different spectral windows. In this dissertation, I unpack how changes to a dye’s molecular structure can affect its ability to undergo J-aggregation, with regard to the design and improvement of the resulting aggregate’s optical properties. Yet, while the optical properties of J-aggregates are unparalleled, one of the greatest challenges preventing their widespread use remains controlling their self-assembly into highly ordered nanostructures. Namely, they boast superradiant emission from their excitonic states, leading to extraordinarily fast energy transfer and amplified radiative rates. In this form, not only do their absorption and emission redshift due to dipolar coupling, but many exciting properties emerge from the coherent coupling of their excitations over long distances. J-aggregates are comprised of conjugated organic molecules that, when given the correct solvation conditions, self-assemble into a slip-stacked arrangement. ![]()
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