Tailoring Functional organic materials through supramolecular chemistry

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Our research encompasses the design, synthesis and study of functional organic materials. These efforts can be broadly categorized into two major avenues of inquiry: (a) determining how molecular structure relates to the self-assembly of ordered materials, and (b) the design of new materials whose properties can be altered using external stimuli such as light. An overarching goal of our research is to establish general methods whereby supramolecular interactions can be rationally exploited in the creation of new materials. To this end, we strive to understand how molecules interact with each other and how these interactions can be manipulated using light. *** Our first broad research theme focuses on the formation of columnar liquid crystal phases by disc-shaped molecules. These phases have been widely targeted as organic semiconducting materials for LEDs, photovoltaics and field effect transistors. Much of their promise stems from their high charge carrier mobilities, their ease of alignment and their ability to self-heal. Our aim is to elucidate the rules that govern the formation of these liquid crystals. We developed a highly modular synthetic approach that facilitates the preparation of families of disc-shaped targets, which allowed us to probe the effects of functional groups, size, and symmetry on phase behavior. Whereas our previous efforts focused on isolating these effects, future studies will tackle the more challenging problem of unraveling how different structural features can either work with or against each other during self-assembly. Understanding this subtle interplay is critical for designing multifunctional materials.***We will also examine what happens when the molecular building blocks are flexible rather than rigid. Discotic dimers, composed disc-shaped groups linked by a flexible spacer, can adopt a wide variety of conformations, making it difficult to predict how they will self-assemble. By studying their conformational dynamics in solution, we hope to gain insights into their ability to organize into liquid crystalline materials. Ultimately, these flexible molecules will open new avenues towards creating highly structured materials at the nanoscale. ****Another major research theme is the use of anthracene photochromism in the design of new materials. We have recently created an efficient photoswitch based on two anthracene groups linked by a flexible spacer; this molecule can be reversibly switched between an open and closed form using different wavelengths of light. In our future studies, we will prepare analogs of this system in order to better understand its photochemical properties, which will also facilitate the creation of new derivatives with improved performance. We will also examine how the large changes in shape and rigidity that accompany this photoswitching can be exploited in the design of photoresponsive materials.********