Synthesis and characterization of self-assembling peptides bearing pi-conjugated subunits to study pi-pi interactions

Inspired by complex natural systems that are derived from molecular components such as lipids and enzymes which have evolved specific function due to their 3-D architecture, the goal of creating function through the assembly of simple precursors is an attractive pursuit. Supramolecular systems derived from monomeric units that develop function as a result of their assembly are beginning to transition into neighboring fields spanning molecular devices and materials. In conjugated polymers, intramolecular electronic delocalization is typically limited by the effective conjugation length of the material, and intermolecular interactions become increasingly important when considering bulk electronic transport processes. The molecular approach of supramolecular chemistry can aid in the design and understanding of specific intermolecular interactions of pi-conjugated subunits by studying subtle perturbations in aggregate geometry and its effects on the resulting photophysics. This dissertation will explore the ability for short oligopeptides to be used as a functional scaffold for the development of materials that span the emerging fields of nanobiotechnology as well as the ability to study intermolecular interactions of pi-conjugated materials.;Discussed will be the synthetic efforts to create oligopeptide constructs that contain an embedded pi-conjugated subunit within the peptide backbone. New methodology will be presenting that incorporate conjugated diacids into oligopeptides via an on-resin dimerization to create an overall symmetric peptide capable of forming parallel beta-sheet networks.;We then move into the realm of the potential applications. Answering the question of whether these self-assembled systems with their intermolecular stacking in an aqueous environment can facilitate charge transport. We utilized a new technologically simple processing technique and adapted it for use with our system to develop aligned domains on the macroscale that gave rise to unique anisotropic properties and enhanced charge migration along the axis of alignment. These properties arose due to the order of the system and the effect it had on the pi-conjugated subunits.;Next we take a more fundamental approach to understanding the role that order and orientation play on the optoelectronic properties of the aggregates. By synthesizing structural analogs of these peptide-pi-peptide constructs we developed a structure/property relationship that allowed us to determine the important factors in the design of the peptides. Initial structural analogs showed the ability to tune the electronic coupling between adjacent subunits, possibly creating a tunable scaffold for studying intermolecular interactions.