Microfluidic synthesis of MOFs, COFs, and HOFs: Insights and advances

Metal-Organic Frameworks (MOFs), Covalent Organic Frameworks (COFs), and Hydrogen-bonded Organic Frameworks (HOFs) (collectively MCHOFs) are increasingly recognized for their diverse applications in catalysis, drug delivery, separation, sensing, adsorption etc. However, their large-scale production using conventional methods faces significant challenges such as slow kinetics, insufficient control over reaction conditions, wide particle size distribution, and poor reproducibility. Microfluidic synthesis has emerged as a promising and greener solution, offering precise control over reaction conditions and product properties with high reproducibility, while significantly reducing waste generation and cutting synthesis time to minutes. Consequently, it has established itself as one of the most promising and sustainable approaches for industrial production of MCHOFs. This work provides a comprehensive overview of microfluidic synthesis of MCHOFs, covering key topics such as the fundamentals of microfluidics, materials for microfluidic fabrication, and microfluidic reactor configuration. It further covers chemistry underlying MCHOFs synthesis, conventional synthesis methods and their limitations, advances in MCHOFs synthesis enabled by microfluidics, synthesis variables, and techno-economic-environmental implications of microfluidic synthesis. Lastly, it identifies key gaps in the microfluidic synthesis of these materials, highlighting feasible future research directions to enhance the sustainability of microfluidic synthesis. By addressing these, it significantly contributes towards greener, efficient, and sustainable industrial-scale production of these materials. • Microfluidic synthesis significantly improves MCHOFs synthesis efficiency hence sustainability. • Less than 1 % MCHOFs microfluidically, hence sustainably, synthesized to date. • MCHOFs properties improved by microfluidic synthesis.