Related Experiment Video
Updated: Jun 25, 2026
08:42
Microfluidic-based Synthesis of Covalent Organic Frameworks (COFs): A Tool for Continuous Production of COF Fibers and Direct Printing on a Surface
Published on: July 10, 2017
Direct Construction of Magnetic and Electrical Two-Dimensional Radical Covalent Organic Frameworks
Rajendra Prasad Paitandi1, Madhurima Giri2, Ryosuke Koyae2
1Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Kyoto, Japan. r.paitandi@gmail.com.
Nature Communications
|June 23, 2026
Summary
Researchers synthesized hexagonal 2D radical covalent organic frameworks (RCOFs) using a novel bottom-up approach. These RCOFs exhibit tunable spin density and antiferromagnetic properties, showing potential for advanced electronics.
Area of Science:
- Materials Science
- Organic Chemistry
- Condensed Matter Physics
Background:
- Two-dimensional (2D) hexagonal networks of radicals offer unique magnetic and electronic properties for spintronics.
- Direct synthesis of such materials is hindered by a lack of stable, symmetry-matched radical building blocks.
Purpose of the Study:
- To develop a bottom-up synthesis strategy for hexagonal 2D radical covalent organic frameworks (RCOFs).
- To investigate the magnetic, electronic, and optical properties of the synthesized RCOFs.
Main Methods:
- Schiff-base condensation of a planar verdazyl radical amine (V-NH2) with aldehydes to form RCOFs (VTPT and VPMT).
- Electron Paramagnetic Resonance (EPR) and Superconducting Quantum Interference Device (SQUID) measurements to confirm spin concentration and magnetic interactions.
- Fabrication and characterization of thin films to assess electronic properties like photoconductivity.
Main Results:
- Successfully synthesized highly crystalline hexagonal 2D RCOFs with unpaired electrons at the framework nodes.
- Demonstrated precise control over spin density by modulating spin-spin distances between building blocks.
- Confirmed high spin concentration and antiferromagnetic interactions at low temperatures, tunable via interlayer coupling.
- Observed enhanced photoconductivity in VTPT thin films with preferential in-plane orientation due to improved π-conjugation.
Conclusions:
- Established a direct synthetic route to hexagonal 2D RCOFs.
- Highlighted the potential of these RCOFs as pseudo 1-dimensional antiferromagnetic materials for electronic applications.
Related Concept Videos
01:07Radicals: Electronic Structure and Geometry
This lesson delves into the geometry of a radical, which is influenced by the electronic structure of the molecule. The principle is similar to that of a lone pair, where the unpaired electron influences the geometry at the radical center.
Accordingly, the structure of a trivalent radical lies between the geometries of carbocations and carbanions. An sp2-hybridized carbocation is trigonal planar, while an sp3-hybridized carbanion is trigonal pyramidal. Here, the difference in geometry is...
Accordingly, the structure of a trivalent radical lies between the geometries of carbocations and carbanions. An sp2-hybridized carbocation is trigonal planar, while an sp3-hybridized carbanion is trigonal pyramidal. Here, the difference in geometry is...
01:03Radical Formation: Overview
A bond can be broken either by heterolytic bond cleavage to form ions or homolytic bond cleavage to yield radicals. A fishhook arrow is used to represent the motion of a single electron in homolytic bond cleavage. There are two main sources from which radicals can be formed:
Radicals from spin-paired molecules:
Radicals can be obtained from spin-paired molecules either by homolysis or electron transfer. While two radicals are formed in the former, an electron is added in the latter, also known...
Radicals from spin-paired molecules:
Radicals can be obtained from spin-paired molecules either by homolysis or electron transfer. While two radicals are formed in the former, an electron is added in the latter, also known...
00:47Radical Formation: Addition
Radicals can be formed by adding a radical to a spin-paired molecule. This is typically observed with unsaturated species, where the addition of a radical across the π bond leads to the production of a new radical by dissolving the π bond. For example, the addition of a Br radical to an alkene yields a carbon-centered radical.
Similar to charge conservation in chemical reactions, spin conservation is implicit for radical reactions. Accordingly, the product formed must possess an unpaired...
Similar to charge conservation in chemical reactions, spin conservation is implicit for radical reactions. Accordingly, the product formed must possess an unpaired...
01:27π Molecular Orbitals of the Allyl Radical
Allyl radicals are three-carbon conjugated systems. They are readily formed as intermediates in halogenation reactions of alkenes involving the addition of halogen to the allylic carbon instead of the double bond. As seen in allyl cations and anions, each of the three sp2-hybridized carbon atoms in allyl radicals has an unhybridized p orbital. These orbitals combine to give three π molecular orbitals.
The allyl systems have identical molecular orbitals but differ in the number of π electrons.
The allyl systems have identical molecular orbitals but differ in the number of π electrons.
01:11Radical Reactivity: Overview
Radicals, the highly reactive species, gain stability by undergoing three different reactions. The first reaction involves a radical-radical coupling, in which a radical combines with another radical, forming a spin‐paired molecule. The second reaction is between a radical and a spin‐paired molecule, generating a new radical and a new spin‐paired molecule. The third reaction is radical decomposition in a unimolecular reaction, forming a new radical and a spin‐paired molecule. These three...
02:06Newman Projections
Different notations are used to represent the three-dimensional structure of molecules on two-dimensional surfaces. One of the most commonly used representations is the dash-wedge formula. The dashed wedges, solid wedges, and the plane lines indicate the groups situated behind the plane, coming out of the plane, and in the plane, respectively.
The organic molecules rotate across the single bonds leading to numerous temporary three-dimensional structures of varying energy known as conformers.
The organic molecules rotate across the single bonds leading to numerous temporary three-dimensional structures of varying energy known as conformers.