Polycyclic aromatic hydrocarbons (polyacenes) are benchmark materials for organic opto-electronic applications. However, these compounds have poor stability and low charger-carrier mobilities to implement them in electronic devices for commercial applications.  One method of tuning the properties of the organic acenes can be the incorporation of a redox-active metal center on them as an integral part of the molecule. Our research is directed to develop methodologies to synthesize π-extended metallocenes to take the organic acene chemistry to the organometallic arena. Instead of using ready-made organic ligand precursors, our approach is to synthesize metallocene-fused carbocyclic ligands - starting from metallocenes and then and their subsequent reductive-aromatization. For this purpose, we react ferrocene with organic anhydrides under Friedel-Crafts conditions to give keto-carboxylic acids. The keto group is reduced to methylene under Clemmensen conditions to facilitate ring-closing in the presence of trifluoroacetic anhydride to give ketones with 2 to 4 carbocyclic rings. We are currently working on aromatization of these carbocyclic ligand so that pi conjugation of the cyclopentadienyl ring can be extended to aromatic backbone. Synthesis, characterization, and redox properties of various complexes will be discussed.

Synthetic methodologies of metallocene-fused polyacenes

2019 Spring National Meeting

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