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Related Concept Videos

Colors and Magnetism03:02

Colors and Magnetism

11.5K
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...
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Valence Bond Theory02:42

Valence Bond Theory

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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...
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Crystal Field Theory - Octahedral Complexes02:58

Crystal Field Theory - Octahedral Complexes

26.1K
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
26.1K
Crystal Field Theory - Tetrahedral and Square Planar Complexes02:46

Crystal Field Theory - Tetrahedral and Square Planar Complexes

41.4K
Tetrahedral Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
41.4K
Complexation Equilibria: The Chelate Effect01:19

Complexation Equilibria: The Chelate Effect

435
In complexation reactions, metal atoms or cations interact with ligands to form donor-acceptor adducts called metal complexes. Ligands that bind through one donor site are monodentate, ligands with two donor sites are bidentate, and those with more than two donor sites are polydentate ligands. For example, ethylene diamine is a bidentate ligand that binds through two nitrogen donor atoms, forming a five-membered ring. EDTA is a polydentate ligand that binds through four oxygen and two nitrogen...
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Coordination Number and Geometry02:57

Coordination Number and Geometry

15.5K
For transition metal complexes, the coordination number determines the geometry around the central metal ion. Table 1 compares coordination numbers to molecular geometry. The most common structures of the complexes in coordination compounds are octahedral, tetrahedral, and square planar.
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Related Experiment Video

Updated: Jun 3, 2025

Radio Frequency Magnetron Sputtering of GdBa2Cu3O7âˆ'ÃŽ ´/ La0.67Sr0.33MnO3 Quasi-bilayer Films on SrTiO3 STO Single-crystal Substrates
06:49

Radio Frequency Magnetron Sputtering of GdBa2Cu3O7âˆ'ÃŽ ´/ La0.67Sr0.33MnO3 Quasi-bilayer Films on SrTiO3 STO Single-crystal Substrates

Published on: April 12, 2019

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Magnetocaloric Effect in 3D Gd(III)-Oxalate Coordination Framework.

Fang-Wen Lv1, Mei-Xin Hong1, Xue-Ting Wang1

  • 1Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of Education, School of Materials Science and Engineering, Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, China.

Nanomaterials (Basel, Switzerland)
|January 10, 2025
PubMed
Summary

New metal-organic frameworks (MOFs) show promise as cryogenic magnetic refrigerants. Gd-3D exhibits superior magnetocaloric effect performance compared to commercial gadolinium gallium garnet, making it ideal for low-temperature cooling applications.

Keywords:
3D frameworkGd(III)-based complexmagnetic refrigerationmagnetocaloric effectoxalate

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An Aptamer-based Sensor for Unchelated GadoliniumIII
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An Aptamer-based Sensor for Unchelated GadoliniumIII

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Preparation, Purification, and Characterization of Lanthanide Complexes for Use as Contrast Agents for Magnetic Resonance Imaging
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Preparation, Purification, and Characterization of Lanthanide Complexes for Use as Contrast Agents for Magnetic Resonance Imaging

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Last Updated: Jun 3, 2025

Radio Frequency Magnetron Sputtering of GdBa2Cu3O7âˆ'ÃŽ ´/ La0.67Sr0.33MnO3 Quasi-bilayer Films on SrTiO3 STO Single-crystal Substrates
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Radio Frequency Magnetron Sputtering of GdBa2Cu3O7âˆ'ÃŽ ´/ La0.67Sr0.33MnO3 Quasi-bilayer Films on SrTiO3 STO Single-crystal Substrates

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An Aptamer-based Sensor for Unchelated GadoliniumIII
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Preparation, Purification, and Characterization of Lanthanide Complexes for Use as Contrast Agents for Magnetic Resonance Imaging
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Preparation, Purification, and Characterization of Lanthanide Complexes for Use as Contrast Agents for Magnetic Resonance Imaging

Published on: July 21, 2011

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Area of Science:

  • Materials Science
  • Magnetism
  • Low-Temperature Physics

Background:

  • Magnetocaloric effect (MCE) refrigerants are potential replacements for Helium-3.
  • Gadolinium (Gd)-based complexes are effective low-temperature magnetic refrigerants.

Purpose of the Study:

  • To synthesize and characterize novel Ln(III)-based metal-organic frameworks (MOFs) for cryogenic magnetic refrigeration.
  • To evaluate the magnetocaloric properties of the synthesized MOFs.

Main Methods:

  • Synthesis of Ln-3D MOFs (Ln = Gd/Dy) using in situ oxalate release from organic ligands.
  • Structural analysis of the 3D framework.
  • Magnetic measurements to determine the magnetocaloric effect (-ΔSm).

Main Results:

  • The synthesized Ln-3D MOF features a neutral 3D framework with 1D channels.
  • Gd-3D demonstrated a maximum magnetic entropy change (-ΔSm) of 36.6 J kg⁻¹ K⁻¹ at 2 K and 7 T.
  • At 2 K and 3 T, Gd-3D showed a -ΔSm of 28.4 J kg⁻¹ K⁻¹ which is significantly higher than Gd₃Ga₅O₁₂ (GGG).

Conclusions:

  • The synthesized Gd-3D MOF exhibits excellent low-temperature magnetocaloric properties.
  • Gd-3D is a promising candidate for efficient cryogenic magnetic refrigeration applications.
  • This research contributes to the development of advanced cooling technologies.