Substrate templated synthesis of single-phase and uniform Zr-porphyrin-based metal-organic frameworks

Abstract

In the synthesis of highly applicable metal-organic frameworks (MOFs), obtaining pure phases poses a great challenge since some MOFs have diverse phases with the same metal sources and ligands. Among such MOFs, PCN-223 and PCN-221 can easily be formed together in a one-pot reaction, making it hard to separate them in a single phase. It is known that some PCN series have a kinetic relationship in the early stages of their formation mechanisms. Thus, we have dedicated our efforts to finding the kinetic relationship between PCN-223 and PCN-221 by utilizing the chemical bath deposition (CBD) method to establish reaction parameters for their pure phases. We found that one out of the two phases can be transformed into the other phase by varying the Zr precursors, water amount, modulators, substrates, and reaction time. Furthermore, the pure phase of PCN-221 with a distinct open-pore channel of 100 nm, which has not been obtained previously, can be synthesized through the CBD method. In this work, we successfully demonstrate that the CBD method is a versatile method for synthesizing phase-pure and uniform MOFs by controlling their nucleation stage and pore structures.