RUI: Self-Assembling Porphyrins and Porphyrin-Modified Peptides and Studies of Their Photoelectronic Properties

Haverford College, Haverford PA

Investigators

Abstract

Supramolecular directed self-assembly (DSA) has the potential for realizing well-defined and well-regulated macromolecular structures with self-limiting dimensions and designed functionality. This project seeks to develop an understanding of the basic science governing DSA of functional monomers, and the photonic and electronic properties of the resulting structures. The research plan is based on close interplay between molecular modeling and design, synthesis of building blocks and scaffolds, spectroscopic characterization of self-assembly under varying conditions, and structural and physical characterization of the resulting assemblies using a variety of scanned probe and electron microscopies, and electrical measurements under controlled illumination and temperature. The focus of these studies will be materials made from the assembly of porphyrins into one-dimensional structures. Related to the chlorophylls found in photosynthetic organisms, porphyrins can form structures that are photophysically and photochemically active. Studies will focus on the self-organization of porphyrins, and their self-assembly with the aid of peptide scaffolds to give control over the geometry and photoelectronic properties of the final assemblies. The underlying mechanisms of the photoelectronic properties will also be explored, to evaluate possible use of the building blocks for devices, such as conducting nanowires, solar cells, and chemical sensors. With this RUI award, the Office of Multidisciplinary Activities and the Organic and Macromolecular Chemistry Program are supporting the research of Professors Karin S. Akerfeldt, Robert Fairman, and Walter Fox Smith, of the Departments of Chemistry, Biology, and Physics (respectively) at Haverford College. This collaborative team is studying the phenomenon of molecular self-assembly, by which smaller molecules spontaneously assemble into structurally-defined aggregates. Mastery of the rules for designing molecular assemblies, by controlling the structure and chemical properties of the basic building blocks, would permit the creation of nanometer- to micron-size assemblies with desired shapes, reactivity, and photonic or electronic properties. Such control would represent a powerful approach to the design and manufacture of devices big and small, with atomic-scale precision in the relative placement of components. Postdoctoral fellows will be given the opportunity to co-teach courses with experienced faculty at Haverford, providing excellent training for careers that involve teaching and research. Aspects of the collaborative research efforts will be exported to workshops for high school teachers, and high school students will be hosted for six-week summer research experiences.