Metal-Catalyzed Diradical Reactivity: From Fundamental Thermal- and Photo-Chemistry to Novel Nanomaterials

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This award in the Chemical Synthesis (SYN) program supports work by Professor Jeffrey M. Zaleski at Indiana University to probe the geometric and electronic factors that control metal-catalyzed and photochemical diradical generation by Bergman cyclization. The unusual diyne-ene chemical functionality undergoes cyclization to form a highly reactive diradical intermediate that can trigger and participate in polymerization reactions, as well as undergo radical reactions with chemical substrates. The reactions can be controlled by choice of metal catalyst and structure of the bound enediyne motif, or by the nature of the chromophore used to trigger the reaction with light. Four chemical systems that span different architectural classes of molecules from large porphyrin chromophores to small inorganic molecules and coated nanoparticles will be prepared and their reactivities examined. The structures of complexes and their electronic properties will be correlated with the activation energy required to generate potent diradicals. Parameters from the most facile systems will then be used to screen their reactivities against chemical substrates.The results may ultimately contribute to applications of radicals in synthetic chemistry as well as advanced chemical reagents for magneto- or phototherapy in hypoxic environments. The project is also multifaceted in synthesis and spectroscopy, and thus develops undergraduate and graduate students on both preparative and mechanistic chemical foundations.