(183d) In Situ Bottom-up Synthesis of Porphyrin-Based Covalent Organic Frameworks

Porphyrins and metalloporphyrins are functional molecules that offer a variety of applications, such as those in optoelectronic, luminescent, molecular logic devices, solar energy harvesting systems, photonic materials, and therapeutics.¹ It has been shown that porphyrins and metal-porphyrins can be employed as electrocatalyst for oxygen reduction reaction (ORR) in fuel cells and metal-air batteries.^2,3 Here, the focus is given to the unique feature of electropolymerization of tetrakis(4-aminophenyl)porphyrin (TAPP) and cobalt- tetrakis(4-aminophenyl)porphyrin (Co-TAPP) in organic media through phenazine linkers formation. The results have shown that the polymer structure and organization is highly dependent on the experimental conditions such as temperature, electropolymerization rate, electrode surface, and the monomer concentration. The appearance of crystalline domains and heterostructure of pTAPP and p(Co-TAPP) with the basal plane of the TAPP molecules parallel to the surface and an extended, micron length scale, p-p stabilized superstructure perpendicular to the surface where confirmed. By adjusting the synthetic parameters, we demonstrated the possibility of bottom-up synthesis of these COF dendrites. We observed a structure-to-function relationship between the ordering of the covalent organic polymers and their electrocatalytic activities in reducing oxygen in an alkaline media.

References

1. Lian, Wenhui, et al. "Synthesis and properties of 5, 10, 15, 20-tetra [4-(3, 5-dioctoxybenzamidephenyl] porphyrin and its metal complexes." Journal of the Serbian Chemical Society3 (2012): 335-348.
2. Day, Nicholas U., and Carl C. Wamser. "Poly-tetrakis-5, 10, 15, 20-(4-aminophenyl) porphyrin Films as Two-Electron Oxygen Reduction Photoelectrocatalysts for the Production of H₂O₂." The Journal of Physical Chemistry C21 (2017): 11076-11082.
3. Walter, Michael G., and Carl C. Wamser. "Synthesis and characterization of electropolymerized nanostructured aminophenylporphyrin films." The Journal of Physical Chemistry C17 (2010): 7563-7574.