Rolling two-dimensional covalent organic framework (COF) sheets into one-dimensional electronic and proton-conductive
Zhuowei Li1, Rajendra Prasad Paitandi1, Yusuke Tsutsui1
1Department of Molecular Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan.
Summary
Researchers transformed 2D covalent organic framework (COF) sheets into 1D nanotubes. These nitrogen-containing diazapyrene-based COF nanotubes show excellent electronic and proton conductivity.
Area of Science:
- Materials Science
- Nanotechnology
- Organic Chemistry
Background:
- Carbon allotropes like graphene (2D) and carbon nanotubes (1D) exhibit unique properties.
- Covalent Organic Frameworks (COFs) are versatile 2D materials with tunable electronic properties.
- Controlling the dimensionality of COFs is crucial for developing advanced functional materials.
Purpose of the Study:
- To develop a method for transforming 2D COF sheets into 1D nanotubular structures.
- To investigate the influence of nitrogen incorporation on the properties of COF nanotubes.
- To explore the potential of these 1D COF nanostructures for electronic and proton conduction.
Main Methods:
- In situ self-assembly of 2D π-conjugated COF sheets at solvent interfaces to form 1D nanotubes.
- Synthesis of diazapyrene-based COFs and pyrene COFs for comparative studies.
- Characterization of the structural, optical, electronic, and proton-conducting properties of the resulting nanotubes.
Main Results:
- Facile "roll-sheets" self-assembly successfully produced coaxial nanotubes with uniform diameters from diazapyrene-based COFs.
- Nitrogen incorporation in the pyrene core significantly altered optical and electronic properties compared to pyrene COFs.
- The diazapyrene-based 1D nanotubular COFs demonstrated simultaneous electronic and proton conductivity.
- Record proton conductivity (σ = 1.98 S cm⁻¹) was achieved, with nitrogen centers acting as doping and proton acceptor sites.
- The nanotubes exhibited stable conducting pathways under ambient conditions.
Conclusions:
- A novel method for creating 1D nanotubular COFs from 2D sheets via self-assembly was established.
- Diazapyrene-based COFs are suitable for forming 1D nanotubes with distinct properties compared to pyrene COFs.
- The synthesized 1D nanotubular COFs possess excellent electronic and proton conductivity, making them promising for energy applications.
- These materials offer a unique platform with segregated electronic and proton conduction pathways (wall and core, respectively).
