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One of the main goals in the field of supramolecular polymer chemistry is to synthesize molecular architectures that aid in mimicking the complexity of living systems. Here, we studied symmetric 1,3,5-benzenetricarboxamide (BTA) that have the ability to self-assemble into fibers in water and exchange monomers. The complexity of their system was increased by adding a multivalent recruiter able to cluster BTAs based on electrostatic interactions. The goal of this research was to compare the clustering kinetics of BTA with eleven and twelve carbon aliphatic spacers and to identify the experimental conditions – monomer concentration, temperature – that creates a super selective monomer clustering. In order to monitor this exchange, the BTA fibers were labeled with separate Cyanine 3 and Cyanine 5 dyes, which were well suited for Förster resonance energy transfer (FRET). Fluorescence spectroscopy monitored the energy transfer from Cy3 to Cy5 dyes and the proximity of the dyes to each other. Single stranded DNA (ssDNA) was used as a multivalent tool to induce clustering of monomers due to its ability to bind the charged monomers. The electrostatic interactions are important because the super selective binding can only be observed with weak interactions. Super selective behavior was probed by varying DNA lengths and charge density of the BTA containing eleven carbon aliphatic spacers. The determination of clustering kinetics of dye-labeled BTAs provides more information on the role of multivalency in clustering in these supramolecular polymers and its ability to model biological systems.
Another project was the synthesis of symmetric azide-functionalized BTA consisting of a twelve-carbon hydrophobic spacer in order to dye-label a glucose BTA derivative for further kinetic exchange experiments. This was done first with a model sugar, mannose, to determine if it was possible to azide-functionalize the sugar through tosylation. The ability to attach an azide in place of the primary alcohol is significant because it allows for copper-catalyzed Huisgen Cycloaddition with an alkyne, allowing many molecules, such as dyes, to attach to these sugars. Once successfully functionalizing the model sugar, the procedure was repeated with an alkyne glucose in order to follow the same azide-alkyne cycloaddition with the BTA derivative.