o-Phenylenes: Controlled Folding and Directed Oxidative Planarization

Miami University, Oxford OH

Investigators

Abstract

Professor C. Scott Hartley of the Department of Chemistry & Biochemistry at Miami University (Ohio) is supported in an award from the Macromolecular, Supramolecular, and Nanochemistry Program for research focusing on the ortho-phenylenes (o-phenylenes). These form a simple class of conjugated polymers that have recently been shown to spontaneously fold into conformations similar to alpha-helices, with aromatic stacking interactions in place of hydrogen bonding. Methods are being developed in this work to control and exploit this folding to give molecules with complex, functional three-dimensional structures. Further, the o-phenylenes are being used as substrates for the synthesis of graphene fragments. Synthetic methods developed as part of this goal should be of broad interest in the bottom-up preparation of graphene nanostructures, and the specific target compounds have been identified as a new class of liquid crystals with board-like structures. The o-phenylenes, as investigated in this project, link disparate but important areas of organic materials chemistry and nanotechnology. First, non-biological molecules that fold analogously to protein subunits have long been sought because of their potential in areas such as catalysis and energy conversion. Because of their structural simplicity, o-phenylenes may be an important platform to address the challenge of deriving complex, functional structures by assembling smaller folded pieces. Second, graphene is arguably the most important single material under development for future applications in nanoelectronics. Structurally well-defined graphene pieces are important to understanding the basic properties of graphene and have their own applications; in this project, the targets are members of an unusual class of liquid crystals with potential in organic electronics and high performance light valves. Broader impacts of this project include the training students in organic synthesis, liquid crystals characterization, computational chemistry, and various forms of spectroscopy, as well as fundamental concepts in molecular design, conformational analysis, self-assembly, and electronic structure. Some experiments have been designed to have significant pedagogical value for less-experienced researchers; the project includes an outreach effort to get high school teachers involved in the research experience.