Growth Process of Two-Dimensional Metal–Organic Framework Cu-BDC: A Particle Attachment Crystallization Mechanism Revealed by Microdroplet Flow Reaction

Abstract

Two-dimensional (2D) metal−organic frameworks (MOFs) have attracted significant attention because of their exotic physicochemical properties. However, the whole picture of the reaction-crystallization process of 2D MOFs remains ambiguous. Unlike common batch-scale reactors, the microdroplet flow (MF) reaction allows for accurate controlling of reaction time, temperature, and reactant concentration, rendering it a technique that is especially well-suited for studying the crystallization processing of MOFs. Here, different statuses of Cu-BDC during the crystal growth process were successfully captured and the nonclassical crystallization mechanism of 2D MOFs was revealed through the MF reaction technique. Benefiting from more accessible exposed active site on the surface, the intermediate state product of Cu-BDC nanosheets exhibited better catalysis performance in the oxidative cyclization reaction. This mechanism of the 2D Cu-BDC growth process is promising for the rational design of various 2D MOFs with special structures.

Inversely Finding Peculiar Reaction Conditions toward Microfluidic Droplet Synthesis

“…The metal-organic frameworks (MOFs), which play an important role in the field of metal coordination chemistry, often produce products in which metal ion/organic ligand units repeat infinitely three-dimensionally in crystals due to the self-assembly process according to conventional synthetic methods. As well as manipulating interfacial reactions to obtain two-dimensionality, microdroplets have been reported to be useful for constraining repetition to dimensionality and finite size [22][23][24][25].…”