Grady, C. (2022). It’s Lit: Synthesis of Phenazine Tetraphenyl Ethylene. Retrieved from https://doi.org/10.14418/wes01.1.2537
Recent developments in organic semiconductors, such as organic light emitting diodes (OLEDs,) have enabled the potential for more synthetic organic contributions to optoelectronics. Previous work by the Northrop group suggested the potential for boronate ester semiconductive covalent organic frameworks, however their capacity for development was limited by their weak conjugation through the empty p orbital in boron and their sensitivity to water. Phenazine linkages however offered the possibility of improved conjugation which would enhance conductivity and stability under a broad range of experimental conditions. Eighty-five functionalized phenazines were studied computationally at the B3LYP-6/311G(d) and M06-2x/6-311G(2p,d) levels of theory to observe the effect of structure and functionality on the enthalpy and free energy of phenazine formation and their HOMO-LUMO gaps. The phenazine formations were predicted to be too favorable (∆Gº ≥ -8.0 kcal/mol) to synthesize COFs by dynamically reversible reactions, but their calculated HOMO-LUMO gaps ranged from 2.5 to 4 eV which qualified some to be semiconductors. These findings pivoted the synthetic project towards investigating the optical properties of phenazines, specifically how they might affect the aggregation induced emission (AIE) of tetraphenyl ethylene. Three methods were attempted in the synthesis of a phenazine tetraphenyl ethylene derivative. Ultimately mPhTPE3 was successfully synthesized via Suzuki coupling, and its AIE fluorescence was preliminarily measured using a Horiba Jobin Yvon FluoroMax-4 Spectrofluorometer.