(649g) Electrochemical Polymerization of Polyfunctional Macrocyclic Monomers: Bottom-up Synthesis of Porphyrinic Covalent Organic Frameworks

Due to their promising characteristics, such as intrinsic porosity and tunable electronic and optical properties, covalent organic frameworks (COFs) have attracted widespread attention. Porphyrins are one of the building blocks of COF. They can coordinate with transition metal atoms, forming organic-inorganic complexes resembling that of heme and the active center of carbonic anhydrase. These complexes are thought to be active in the electrocatalytic reduction of oxygen and have shown to be promising precursors for the synthesis of platinum group metal (PGM)-free catalysts. Here, we demonstrate the feasibility of assembling van der Waals heterostructures, based on the porphyrin derivatives, using electrochemical deposition, and create porphyrin-based COF materials.¹ We unravel the importance of a set of parameters that strongly control the electropolymerization of tetrakis(4-aminophenyl)porphyrin (TAPP) i.e., temperature, electropolymerization rate, electrode surface, and most importantly additives. Rational adjustment of these parameters enables us to actively control the growth of the crystalline domains of the polymerized-TAPP. Moreover, our results reveal the importance of co-crystallization of porphyrinic frameworks with additives (e.g., pyridine) and a structure-to-function relationship between the ordering of the covalent organic polymers and their ORR activity in alkaline media.

1. Tavakoli, E., Kakekhani, A., Kaviani, S., Tan, P., Mohammadi Ghaleni, M., Asle Zaeem, M., Rappe, A.M. and Nejati, S., 2019. In Situ Bottom-up Synthesis of Porphyrin-based Covalent Organic Frameworks. Journal of the American Chemical Society 2019, 141, 50, 19560-19564