Research areas
MOFs and COFs
Our research focuses on metal–organic frameworks (MOFs) and covalent organic frameworks (COFs), which are porous crystals assembled from molecular building blocks. MOFs are constructed using metal–ligand coordination bonds, while COFs are built with dynamic covalent bonds between organic molecules. Their high porosity, crystallinity, and designability enable us to create molecularly defined solid surface structures, effective for applications such as molecular storage, separation, transport, catalysis, and sensing. While these are relatively new types of substances developed in the 1990s, their potentials are now well recognized not only in fundamental research but also for industrial applications, marked with the Nobel Prize in Chemistry 2025.
Image: (c) Kenichi Endo
Synthesis
Synthesis of MOFs and COFs is usually simple, especially compared to organic synthesis: just mix some chemicals, heat the mixture, wait, and filter the product crystals out. However, it is not trivial to produce a new MOF/COF or to obtain a MOF/COF in high yield and purity with a desired particle size. We master the use of various reagents and conditions to guide the reactions to the desired outcome, while carefully characterizing the products with various analytical techniques to confirm their structure and purity.
Image: (c) Kenichi Endo
Catalysis
As an application of MOFs and COFs, we are especially interested in catalysis. MOFs and COFs can embrace catalytic reactions in their well-defined pores, facilitating the control of the secondary coordination sphere functionalities, substrate conformation, and mass transport. The catalytically active sites can be embedded either by designing metal–ligand nodes, functionalizing organic linkers, grafting molecular catalysts, or encapsulating nanoparticles. The aforementioned pore features can either create new types of catalytic sites or enhance the performance of catalytic sites for higher activity, selectivity, and stability.
Image: (c) ChatGPT
Data
In recent decades, data science has made significant progress so that insights can be efficiently extracted from large data. Such data-driven approaches, as opposed to the conventional intuition-based approach, can accelerate chemical research. For example, the condition optimization of MOF/COF synthesis involves a lot of parameters that can be effectively analyzed by machine learning. However, the effectiveness of such data analysis depends on the data formats and quality. We develop well-standardized, machine-readable data formats using JSON Schema and data processing workflows based on Python, together with an electronic lab notebook (ELN), Chemotion. These tools assist our MOF/COF synthesis and catalysis research.
Image: (c) Kenichi Endo
Specific topics
Porous crystals are materials with a regular atomic network structure that contain nanometer-sized voids capable of selectively adsorbing other molecules. The first of these is zeolites, which have revolutionized catalysis, separation, and storage technologies. In recent decades, metal–organic frameworks (MOFs) and covalent organic frameworks (COFs) have emerged as highly designable porous crystals. MOFs, formed through bonding between metal ions and organic molecules, received the Nobel Prize in Chemistry 2025 for their widespread use and impact across various fields, such as gas storage and separation. COFs, developed later, are constructed similarly but with bonding between organic molecules and are showing promise for applications such as catalysis and energy storage.
However, MOFs and COFs each face limitations in their structural design that restrict the development of their functionalities. MOFs often struggle with chemical stability against water, acid, base, or redox, which limits their options for metal and ligand motifs. Meanwhile, COFs generally have lower porosity and crystallinity, making it more difficult to precisely tune their pore structures. These limitations originate from their synthetic processes. MOFs are constructed through metal–ligand coordination reactions, which are highly reversible, directional, and three-dimensional, resulting in highly porous, crystalline structures but with limited chemical stability. Conversely, COFs are primarily formed through organic condensation reactions, such as imine condensation, which creates stronger bonds and leads to high chemical stability. However, the lower reversibility, reduced directionality, and two-dimensional structure of these connections result in lower porosity and crystallinity compared to typical MOFs.
Considering the complementary properties of MOFs and COFs, I envision that hybridizing their chemistry can create a new class of porous crystalline materials, "MOCOFs," which combines high porosity, crystallinity, and chemical stability. Specifically, I aim to assemble molecular building blocks using both metal–ligand coordination and organic condensation reactions simultaneously, allowing the coordination to guide crystallization and form highly porous structures while the condensation strengthens the formed network.
Recently, we have synthesized the first examples of MOCOFs from CoIII-aminoporphyrins and aldehydes, which self-assembled into porous crystals by Co–amine coordination and imine condensation reactions (Figure below). These porphyrin-based MOCOFs showed high porosity (BET surface area of 2800 m2 g−1) and crystallinity (crystal size of 100 µm in 5 days), as well as high chemical stability against water and base. This result supports my hypothesis that reversible coordination can guide the crystallization and porous structure formation, while polymeric organic condensation helps stabilize the entire framework.
Now we are trying to generalize this concept using more versatile building blocks to create various functional porous crystalline materials.
MOCOFs shown above exhibit a unique combination of porosity, crystallinity, stability, and structural complexity. We are trying to leverage these properties for conducting catalysis within their pores to achieve unusual activity and selectivity in aerobic oxidation of organic molecules.
In collaboration with the Estes Group, we are working on the immobilization of molecular catalysts inside Lewis-acidic MOFs to achieve higher activity, selectivity, and stability in thermocatalytic hydrogenation of CO2 into methanol, a future process for green methanol production.
CO2 + 3H2 → CH3OH + H2O
In collaboration with the Pleiss Group, Hansen Group, Uekermann Group, and NFDI4Chem, we are working on the digital infrastructure for efficient data management in MOF/COF synthesis and catalysis research. We use Chemotion as the electronic lab notebook (ELN) and develop JSON schemas and Python tools to assist data handling. The data analysis can be done by AI and machine-learning (ML) tools.
Collaborations
CRC1333
We are a member of DFG Collaborative Research Center 1333 "Molecular Heterogeneous Catalysis in Confined Geometries," where we work together with many other research groups at our and other universities to identify and utilize "confinement effects" in molecular heterogeneous catalysis. MOFs and COFs provide an excellent handle for the confinement of catalysts and reactants within their designed pores.
NFDI4Chem
We are a participant in the consortium of the German national research data infrastructure for chemistry (NFDI4Chem). Here we work together on the electronic lab notebook Chemotion ELN and data standards.
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