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Related Concept Videos

Colors and Magnetism03:02

Colors 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.
Valence Bond Theory02:42

Valence 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...
Paramagnetism01:30

Paramagnetism

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...
NMR Spectroscopy: Spin–Spin Coupling01:08

NMR Spectroscopy: Spin–Spin Coupling

The spin state of an NMR-active nucleus can have a slight effect on its immediate electronic environment. This effect propagates through the intervening bonds and affects the electronic environments of NMR-active nuclei up to three bonds away; occasionally, even farther. This phenomenon is called spin–spin coupling or J-coupling. Coupling interactions are mutual and result in small changes in the absorption frequencies of both nuclei involved. While nuclei of the same element are involved in...
Ferromagnetism01:31

Ferromagnetism

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...
Diamagnetism01:26

Diamagnetism

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.

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Bio-inspired Polydopamine Surface Modification of Nanodiamonds and Its Reduction of Silver Nanoparticles
07:58

Bio-inspired Polydopamine Surface Modification of Nanodiamonds and Its Reduction of Silver Nanoparticles

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Cobalt - poly(amido amine) superparamagnetic nanocomposites.

James E Atwater1, James R Akse, John T Holtsnider

  • 1UMPQUA Research Company, 125 Volunteer Way - P.O. Box 609, Myrtle Creek, Oregon 97457, USA.

Materials Letters
|March 31, 2010
PubMed
Summary

Metallic cobalt-dendrimer nanocomposites exhibit superparamagnetism. These novel materials, synthesized using Poly(amido amine) dendrimers, show potential for magnetic applications with a blocking temperature around 50 K.

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Published on: December 6, 2021

Area of Science:

  • Materials Science
  • Nanotechnology
  • Magnetism

Background:

  • Dendrimers are highly branched macromolecules with tunable properties.
  • Metallic nanoparticles offer unique magnetic and catalytic functionalities.
  • Combining dendrimers with magnetic nanoparticles creates advanced nanocomposites.

Purpose of the Study:

  • To synthesize and characterize metallic cobalt-dendrimer nanocomposites.
  • To investigate the magnetic properties of these novel nanocomposites.
  • To determine the superparamagnetic behavior and blocking temperature.

Main Methods:

  • Synthesis of cobalt-dendrimer nanocomposites using generation 5 Poly(amido amine) dendrimers.
  • Cobalt loading quantification via atomic absorption spectrophotometry.
  • Magnetic property investigation using SQUID magnetometry from 2-300 K.

Main Results:

  • Successfully prepared cobalt-dendrimer nanocomposites with approximately 38 cobalt atoms per dendrimer.
  • Observed superparamagnetic behavior in the nanocomposites.
  • Determined a characteristic blocking temperature of approximately 50 K.

Conclusions:

  • Cobalt-dendrimer nanocomposites display superparamagnetism.
  • The blocking temperature suggests potential applications in areas like magnetic data storage or biomedical imaging.
  • These findings highlight the promise of dendrimer-templated magnetic nanomaterials.