AbstractsChemistry

Self-assembly is crucial to numerous systems that occur in nature; researchers have often attempted to mimic these natural systems by utilizing non-covalent interactions of amphiphilic systems to form self-assembled structures in solution for useful applications. The Parquette group has discovered a self assembling 1,4,5,8-naphthalenediimide (NDI) diacetylene system with a lysine unit that assembles into a robust one-dimensional nanotube, capable of acting as a surfactant for gold nanoparticle growth. The diacetylene unit is capable of polymerization, as well as changing its conformation to sheets after heating; regardless of the shape or polymerization status of the nanostructures, they were able to act as a stabilized surface for gold nanoparticle growth. Other groups have discovered that gold nanoparticles are attracted to amine functionality electrostatically, decorating the surface of a surfactant. However, there are few examples of self-assembled systems forming nanostructures that can withstand the slightly acidic Turkevich method of reducing gold (III) into gold (0) using citric acid or citrate.Stimuli-responsive materials have been of interest in recent years, due to the interest in mimicking various types of biological systems for different applications. Self-assembling systems are an interesting approach to this research due to its ability to create highly ordered systems quickly. Stimuli-responsive materials react to their chemical and physical environments; therefore, by manipulation of a molecular structure, it is possible to develop a unique set of compounds that react to their environments for applications in optoelectronics, drug delivery, or bio-mimics. In this work, two tetrapeptides with the sequence Phe-Lys-Lys(TPP-Zn)-Lys were developed using a tetraphenylporphyrin ring on the third lysine tail. The difference in the peptides was that one had a free amine on the lysine adjacent to the phenylalanine amino acid, while the other peptide had an acyl-protecting group on the lysine adjacent to the phenylalanine. Due to the Zn-TPP chromophore on the assembly, nitrogen-containing ligands were used to make the structure more defined. With the addition of DABCO or pyridine, the observed structures based on microscopy methods changed depending on the conditions. The tetrapeptides formed ß-sheet structures based on IR data; since anti-parallel and parallel ß-sheets are possible, an isotopic equivalent of each tetrapeptide was synthesized and analyzed by IR. A splitting of the amide I band demonstrates the formation of anti-parallel ß-sheets when the isotope is used; in this case, the amide I band split for both isotopic equivalents indicating anti-parallel ß-sheet formation. Advisors/Committee Members: Parquette, Jonathan (Advisor).