Related Experiment Video
Updated: Aug 8, 2026
06:53
Magnetometric Characterization of Intermediates in the Solid-State Electrochemistry of Redox-Active Metal-Organic Frameworks
Published on: June 9, 2023
The [Fe(III)[Fe(III)(L1)2]3] star-type single-molecule magnet
Rolf W Saalfrank1, Andreas Scheurer, Ingo Bernt
1Institut für Organische Chemie, Universität Erlangen-Nürnberg, Henkestr. 42, 91054, Erlangen, Germany. saalfrank@chemie.uni-erlangen.de
Dalton Transactions (Cambridge, England : 2003)
|June 6, 2006
Summary
This study synthesized a star-shaped iron(III) complex, revealing its single-molecule magnet properties and electronic structure. The complex exhibits easy-axis anisotropy and hysteretic magnetization below 1.2 K.
Area of Science:
- Coordination Chemistry
- Magnetochemistry
- Supramolecular Chemistry
- Materials Science
Background:
- Development of single-molecule magnets (SMMs) is crucial for advancing high-density data storage and quantum computing.
- Iron(III) complexes offer a promising platform for SMM development due to their accessible electronic configurations and magnetic properties.
- Understanding structure-property relationships in polynuclear iron complexes is key to designing efficient SMMs.
Purpose of the Study:
- To synthesize and characterize a novel star-shaped tetranuclear iron(III) complex.
- To investigate the magnetic properties, including spin state, magnetic coupling, and SMM behavior.
- To determine the structural and electronic properties at the molecular level using advanced surface science techniques.
Main Methods:
- Synthesis of the star-shaped complex [Fe(III)[Fe(III)(L1)2]3] from N-methyldiethanolamine and ferric chloride.
- Characterization using Mössbauer spectroscopy, single-crystal X-ray diffraction, SQUID magnetometry, and EPR spectroscopy.
- Surface analysis via Scanning Tunneling Microscopy (STM) and Scanning Tunneling Spectroscopy (STS) on highly ordered pyrolytic graphite (HOPG), complemented by DFT calculations.
Main Results:
- The star-shaped iron(III) complex was successfully synthesized and characterized, exhibiting two distinct high-spin iron(III) sites.
- Single-crystal X-ray diffraction revealed crystallographic details, including the presence of enantiomers and solvent molecules.
- Magnetic studies confirmed antiferromagnetic intramolecular coupling, leading to a S = 10/2 ground state and easy-axis anisotropy, classifying it as an SMM with a blocking temperature of ~1.2 K.
- STM/STS measurements on HOPG demonstrated the formation of molecular clusters, monolayers, and individual molecules, with spectroscopy revealing contrast at metal centers, supported by DFT.
Conclusions:
- The synthesized star-shaped iron(III) complex functions as a single-molecule magnet with tunable magnetic properties.
- Intermolecular couplings, influenced by solvent molecules, play a significant role in the overall magnetic behavior.
- STM/STS provides direct visualization and electronic characterization of individual molecules and their assemblies, validating theoretical predictions.
Related Concept Videos
03:02Colors and Magnetism
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
01:31Ferromagnetism
Materials like iron, nickel, and cobalt consist of magnetic domains, within which the magnetic dipoles are arranged parallel to each other. The magnetic dipoles are rigidly aligned in the same direction within a domain by quantum mechanical coupling among the atoms. This coupling is so strong that even thermal agitation at room temperature cannot break it. The result is that each domain has a net dipole moment. However, some materials have weaker coupling, and are ferromagnetic at lower...
01:26Diamagnetism
Materials consisting of paired electrons have zero net magnetic moments. However, when these materials are placed under an external magnetic field, the moments opposite to the field are induced. Such materials are called diamagnets. Diamagnetism is the response of the diamagnets when placed in an external magnetic field.
Diamagnetism was discovered by Anton Brugmans in 1778 when he observed that bismuth gets repelled by magnetic fields, thus theorizing that diamagnets get repelled by magnets.
Diamagnetism was discovered by Anton Brugmans in 1778 when he observed that bismuth gets repelled by magnetic fields, thus theorizing that diamagnets get repelled by magnets.
02:42Valence Bond Theory
Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...
01:30Paramagnetism
Paramagnets are materials with unpaired electrons that possess a finite magnetic moment. In the absence of a magnetic field, these moments are randomly oriented, and thus the net moment is zero. Under an external field, a torque acting on the moments tends to align them along the field's direction. However, the random thermal motion of electrons produces a torque opposite to the external field and tries to disorient the moments. These two competing effects align only a few moments along the...
01:28Types Of Superconductors
A superconductor is a substance that offers zero resistance to the electric current when it drops below a critical temperature. Zero resistance is not the only interesting phenomenon as materials reach their transition temperatures. A second effect is the exclusion of magnetic fields. This is known as the Meissner effect. A light, permanent magnet placed over a superconducting sample will levitate in a stable position above the superconductor. High-speed trains that levitate on strong...