In Situ Bottom-up Synthesis of Porphyrin-Based Covalent Organic Frameworks

Synthesis and processing of two- or three-dimensional
covalent
organic frameworks (COFs) have been limited by solvent intractability
and sluggish condensation kinetics. Here, we report on the electrochemical
deposition of poly­(5,10,15,20-tetrakis­(4-aminophenyl)­porphyrin)-covalent
organic frameworks (POR-COFs) via formation of phenazine linkages.
By adjusting the synthetic parameters, we demonstrate the rapid and
bottom-up synthesis of COF dendrites. Both experiment and density
functional theory underline the prominent role of pyridine, not only
as a polymerization promoter but as a stabilizing sublattice, cocrystallizing
with the framework. The crucial role of pyridine in dictating the
structural properties of such a cocrystal (Py-POR-COF) is discussed.
Also, a structure-to-function relationship for this class of materials,
governing their electrocatalytic activity for the oxygen reduction
reaction in alkaline media, is reported.