Heterometallic Titanium-Organic Frameworks by Metal-Induced Dynamic Topological Transformations

Area of Science:

• Reticular chemistry and materials science.
• Synthesis and characterization of porous materials.
• Coordination chemistry and solid-state chemistry.

Background:

• Reticular chemistry enables the design of diverse metal-organic frameworks (MOFs) with tunable porosity.
• Synthesizing titanium-based MOFs is challenging due to titanium's high reactivity.
• Existing methods limit the controlled assembly of titanium molecular clusters.

Purpose of the Study:

• To develop a novel methodology for synthesizing heterometallic titanium-organic frameworks.
• To overcome limitations in controlled titanium cluster assembly.
• To explore metal-exchange reactions for MOF synthesis.

Main Methods:

• Metal-exchange reactions on pre-formed MUV-10(Ca) MOF crystals at low temperatures.
• Utilizing the reactivity difference between hard (titanium) and soft (calcium) metals.
• Employing computational simulations to understand thermodynamic control and surface effects.

Main Results:

• Successful synthesis of heterometallic titanium MOFs via metal-exchange, generating variable nuclearity secondary building units (SBUs).
• MOF-to-MOF conversion into bipartite nets driven by SBU formation and thermodynamic control.
• Production of MUV-101(Fe,Co,Ni,Zn) and MUV-102(Cu) MOFs, isostructural with known frameworks, under mild conditions.
• Hierarchical pore structures were controlled by reaction time.

Conclusions:

• A new, low-temperature metal-exchange strategy enables controlled synthesis of heterometallic titanium MOFs.
• This method allows access to titanium MOFs not achievable through conventional solvothermal synthesis.
• The approach offers precise control over MOF topology and porosity, expanding the scope of titanium-based materials.