2D Conjugated Metal-Organic Frameworks: Defined Synthesis and Tailor-Made Functions

Area of Science:

• Materials Science
• Chemistry
• Nanotechnology

Background:

• 2D conjugated metal-organic frameworks (2D c-MOFs) are graphene-like materials with π-conjugated structures, offering unique properties like nanochannels, high conductivity, and tunable band gaps.
• Current limitations in 2D c-MOF exploration stem from the restricted availability of organic linkers and topologies, hindering the development of advanced materials.
• Designing novel ligands is crucial for constructing 2D c-MOFs with improved crystallinity, conductivity, and tailored functionalities.

Purpose of the Study:

• To summarize recent advancements in fine-tuning 2D c-MOF topology through precise ligand design.
• To introduce the concept of utilizing nonplanar ligands for simplified synthesis and enhanced properties of 2D c-MOFs.
• To explore the impact of ligand engineering on the structural diversity, conductivity, and functional applications of 2D c-MOFs.

Main Methods:

• Synthesis of 2D c-MOFs using nonplanar ligands, including in situ Scholl reactions for conjugate polycyclic aromatics.
• Ligand engineering by systematically modifying functional groups on a twisted hexabenzocoronene core to control topology and pore size.
• Incorporation of redox-active components (salphen, pyrazine) into nonplanar ligands via a coupling method.

Main Results:

• Direct synthesis of fully conjugated 2D c-MOFs from nonplanar ligands, simplifying preparation and expanding topological diversity (rhombus, kagome).
• Ligand engineering yielded three distinct hydroxyl ligands, leading to varied coordination node densities, electron transfer abilities, and electrical conductivity.
• Incorporation of redox components resulted in 2D c-MOFs with high catalytic and energy storage capacities, enabling structure-property relationship studies.

Conclusions:

• Nonplanar ligand design offers a versatile strategy for creating 2D c-MOFs with tailored structures, enhanced conductivity, and diverse functionalities.
• These materials show significant promise for applications in electrical, electrochemical, and spintronic devices.
• Further research is needed to address challenges in achieving tailor-made functions and practical applications for 2D c-MOFs.