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Aggregation Induced Emission of Cycloheptatrienylidene Fluorophores

  • Goal: The goal of this project is to use hypervalent iodonium alkynyl triflates to synthesize molecules that fluoresce upon aggregation. This is the group's flagship project and incorporates target synthesis, methodology development, computational chemistry, fluorescence, solid-state chemistry, and metal coordination chemistry.
  • Summary: Typically, luminescence of a fluorophore is decreased as the solution is concentrated thereby rendering many solid state applications impractical. Increasing luminescence upon concentration of a solution can occur in certain cases where there is a restriction of intramolecular rotation in the aggregate. The core structure of the molecules used to accomplish aggregation induced emission will consist of an asymmetrically substituted cycloheptatrienylidene. A new method of synthesizing cycloheptatrienylidenes from hypervalent iodonium alkynyl triflates will be developed for the purpose of exploring how different structural changes can have effects on aggregation. To induce fluorescence, metal salts will be added to the cycloheptatrienylidenes to aromatize the 7-membered ring, cause an aggregation, and produce an emission. The project will also use ab-intio calculations to probe the electronic structure of the synthesized molecules. To translate these complexes into applicable materials, the nature of the excitation will be investigated. Current theories suggest that the emission can come from a charge transfer and/or a d-d transition but this has not been investigated in the literature. A long-term goal for the project is to create non-toxic fluorophores that aggregate and “turn-on” fluorescence by using endogenous metals in the body.