Synthesis of Cu-Trimesic Acid/Cu-1,4-Benzenedioic Acid via Microdroplets: Role of Component Compositions

Mixed-linker metal-organic frameworks (MOFs) offer great tunability in both pore structures and surface chemistry. This study reports the synthesis and characterization of model mixed-linker MOFs (i.e., Cu-TMA/Cu-BDC; BDC = 1,4-benzenedioic acid, TMA = trimesic acid) via a microdroplet-based spray process, to unravel the relationship between the properties of mixed-linker MOFs and the component compositions. The as-prepared mixed-linker MOFs exhibited distinct properties in terms of morphology, crystalline phase, surface chemistry, and pore structure. In particular, two-dimensional correlation spectroscopy (2D-COS) analysis was conducted to analyze the correlational features among surface functional groups, which are unattainable from traditional infrared and Raman spectra. The results from the 2D-COS analysis also suggest that the surface chemistry of the mixed-linker MOFs is adjustable by controlling the precursor conditions. Measurements of CO2 adsorption on the mixed-linker MOFs demonstrated the tunability of the preferential adsorption sites and adsorption kinetics. All the above-mentioned information implies that synthetic parameters can be varied to optimize the performance of the mixed-linker MOFs. The outcome of this study offers new insights into the synthetic chemistry of mixed-linker MOFs in a microdroplet-based spray process.