Crystallizing covalent organic frameworks from metal organic framework through chemical induced-phase engineering

Area of Science:

• Materials Science
• Chemistry
• Nanotechnology

Background:

• Ordered porous frameworks like metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) are typically built from monomers using metal-coordinated or covalent linkages.
• The transformation between different classes of porous materials, such as MOFs and COFs, is an underexplored area with potential for novel properties.

Purpose of the Study:

• To demonstrate a chemical-induction phase-engineering strategy for transforming a 2D conjugated copper-based SA-MOF (Cu-Tp) into a 2D-COF (Cu-TpCOFs).
• To investigate the resulting changes in pore size, metal distribution, crystallinity, porosity, and stability.

Main Methods:

• A chemical-induction strategy was employed to induce a phase transition from a 2D Cu-based SA-MOF (Cu-Tp) to a 2D-COF (Cu-TpCOFs).
• Characterization techniques were used to analyze the structural and property changes, including pore size, metal distribution, crystallinity, porosity, and stability.

Main Results:

• The phase transition successfully transformed Cu-Tp MOF into Cu-TpCOFs, enabling in-situ pore size engineering from 1.1 nm to 1.5-2.0 nm.
• The resulting Cu-TpCOFs exhibited uniform and low metal doping (1-1.5%), along with enhanced crystallinity, porosity, and stability compared to the parent Cu-Tp MOF.
• The successful construction of a new framework from an existing one highlights the potential of phase-engineering strategies.

Conclusions:

• Chemical-induction phase engineering is an effective strategy to transform MOFs into COFs with tailored properties.
• This approach allows for precise control over pore size and improves material characteristics like crystallinity, porosity, and stability.
• The framework-to-framework construction opens new avenues for designing advanced porous materials with tunable functionalities.