Self-assembly of Functional Organic Materials

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The aim of our research is to design dynamic materials that meet the urgent demands for clean air, clean water and clean energy. Our work encompasses the synthesis and detailed investigation of functional organic materials and can be broadly categorized into two major themes: (a) understanding how molecular structure relates to the self-assembly of organic molecules into ordered nanostructures, and (b) creating materials whose properties can be controlled via external stimuli such as light, heat or chemical species. An overarching goal of our work is to establish general methods by which supramolecular interactions can be rationally exploited in the creation of new materials. Our first research theme focuses on the assembly of aromatic molecules into discotic liquid crystals (DLCs). These phases have been widely studied as materials for light emitting devices, photovoltaics and field effect transistors. Our primary objective is to uncover the rules that govern the assembly of these molecules into the nanostructures that ultimately determine their performance as semiconductors. To this end, we have successfully developed highly modular synthetic approaches that facilitate the preparation of a wide array of target molecules, which has enabled us to study the effects of functional groups, size, symmetry and shape on phase behavior. Our future research will be directed towards hydrophilic DLCs for ion-conductive materials in lithium-ion batteries and fuel cells, and for membranes to facilitate the separation of CO2 from mixtures of gases. We will also examine the self-assembly of flexible molecules, whose behaviour is complicated by their unpredictable shapes. An important new direction is the study of the complex conformational dynamics of these systems in solution and the liquid crystal phase. To answer these questions, we bring to bear a wide range of synthetic, analytical and theoretical tools.   A second major research theme is the development molecular photoswitches based on anthracene. These molecules undergo a bimolecular photochemical reactions to yield covalent dimers, which in turn can be converted to their original form either thermally or by exposure to shorter wavelengths. Our work focuses on designing anthracene-based chromophores that show improved photochemical and photophysical performance, and on exploiting these systems in liquid crystalline optoelectronic devices and chemical sensors.   Materials properties, ranging from the efficiency of solar cells to the bioavailability of pharmaceuticals, depend on the manner in which molecules assemble in the bulk. As such, our program, which pursues fundamental questions regarding the supramolecular chemistry of soft materials, has broad implications across many areas of research and technology.