Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

Valence Bond Theory02:42

Valence Bond Theory

11.1K
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...
11.1K
¹H NMR: Interpreting Distorted and Overlapping Signals01:02

¹H NMR: Interpreting Distorted and Overlapping Signals

1.4K
Spin systems where the difference in chemical shifts of the coupled nuclei is greater than ten times J are called first-order spin systems. These nuclei are weakly coupled, and their chemical shifts and coupling constant can generally be estimated from the well-separated signals in the spectrum.
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are...
1.4K
Spin–Spin Coupling: One-Bond Coupling01:17

Spin–Spin Coupling: One-Bond Coupling

1.4K
Coupling interactions are strongest between NMR-active nuclei bonded to each other, where spin information can be transmitted directly through the pair of bonding electrons. While nuclei polarize their electrons to the opposite spins, the bonding electron pair has opposite spins. Configurations with antiparallel nuclear spins are expected to be lower in energy. When coupling makes antiparallel states more favorable, J is considered to have a positive value. The one-bond coupling constant, 1J,...
1.4K
NMR Spectroscopy: Spin–Spin Coupling01:08

NMR Spectroscopy: Spin–Spin Coupling

2.9K
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...
2.9K
Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)01:20

Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)

1.6K
Two NMR-active nuclei bonded to a central atom can be involved in geminal or two-bond coupling. Geminal coupling is commonly seen between diastereotopic protons in chiral molecules and unsymmetrical alkenes, among others.
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...
1.6K
Spin–Spin Coupling Constant: Overview01:08

Spin–Spin Coupling Constant: Overview

1.4K
In bromoethane, the three methyl protons are coupled to the two methylene protons that are three bonds away. In accordance with the n+1 rule, the signal from the methyl protons is split into three peaks with 1:2:1 relative intensities. The methylene protons appear as a quartet, with the relative intensities of 1:3:3:1.
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must...
1.4K

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Carbon nitride monolayer nanosheets: astrochemical insights into the fate of interstellar hydrogen.

Physical chemistry chemical physics : PCCP·2026
Same author

Gaussian Basis Sets for All-Electron Excited-State Calculations of Large Molecules.

Journal of chemical theory and computation·2025
See all related articles

Related Experiment Video

Updated: Jan 8, 2026

Site Directed Spin Labeling and EPR Spectroscopic Studies of Pentameric Ligand-Gated Ion Channels
11:19

Site Directed Spin Labeling and EPR Spectroscopic Studies of Pentameric Ligand-Gated Ion Channels

Published on: July 4, 2016

11.0K

On entropy driven spin crossover in pristine and fluorinated Fe(phenanthroline)2(NCS)2: Insight from DFT.

R Pasquier1, M Alouani1

  • 1Université de Strasbourg, Institut de Physique et de Chimie des Matériaux de Strasbourg, CNRS-UNISTRA UMR 7504, 67034 Strasbourg, France.

The Journal of Chemical Physics
|December 24, 2025
PubMed
Summary

Fluorine substitution in spin-crossover iron(II) bis(phenanthroline) dithiocyanate (Fephen) molecules dramatically changes their magnetic properties. Pristine Fephen exhibits spin crossover near 167 K, while fluorinated Fephen shows no crossover.

More Related Videos

Measurements of Long-range Electronic Correlations During Femtosecond Diffraction Experiments Performed on Nanocrystals of Buckminsterfullerene
08:44

Measurements of Long-range Electronic Correlations During Femtosecond Diffraction Experiments Performed on Nanocrystals of Buckminsterfullerene

Published on: August 22, 2017

8.0K
Visualizing Uniaxial-strain Manipulation of Antiferromagnetic Domains in Fe1+YTe Using a Spin-polarized Scanning Tunneling Microscope
09:06

Visualizing Uniaxial-strain Manipulation of Antiferromagnetic Domains in Fe1+YTe Using a Spin-polarized Scanning Tunneling Microscope

Published on: March 24, 2019

8.5K

Related Experiment Videos

Last Updated: Jan 8, 2026

Site Directed Spin Labeling and EPR Spectroscopic Studies of Pentameric Ligand-Gated Ion Channels
11:19

Site Directed Spin Labeling and EPR Spectroscopic Studies of Pentameric Ligand-Gated Ion Channels

Published on: July 4, 2016

11.0K
Measurements of Long-range Electronic Correlations During Femtosecond Diffraction Experiments Performed on Nanocrystals of Buckminsterfullerene
08:44

Measurements of Long-range Electronic Correlations During Femtosecond Diffraction Experiments Performed on Nanocrystals of Buckminsterfullerene

Published on: August 22, 2017

8.0K
Visualizing Uniaxial-strain Manipulation of Antiferromagnetic Domains in Fe1+YTe Using a Spin-polarized Scanning Tunneling Microscope
09:06

Visualizing Uniaxial-strain Manipulation of Antiferromagnetic Domains in Fe1+YTe Using a Spin-polarized Scanning Tunneling Microscope

Published on: March 24, 2019

8.5K

Area of Science:

  • Computational materials science
  • Quantum chemistry
  • Solid-state physics

Background:

  • Spin crossover (SCO) materials exhibit distinct magnetic states.
  • Iron(II) complexes like Fephen are model systems for SCO studies.
  • Understanding SCO mechanisms is crucial for molecular electronics and sensors.

Purpose of the Study:

  • Investigate the impact of fluorine substitution on Fephen's electronic and magnetic properties.
  • Determine the temperature-dependent spin crossover behavior of pristine and fluorinated Fephen.
  • Validate computational methods against experimental SCO data.

Main Methods:

  • Ab initio total energy calculations for Fephen on a copper surface.
  • Quasi-harmonic approximation and finite-difference methods for vibrational mode analysis.
  • Free energy calculations to determine SCO transition temperatures.

Main Results:

  • Fluorine substitution in Fephen inverts its magnetic state and inhibits spin crossover.
  • Key vibrational frequencies (N-C-S, Fe-ligand) differ significantly between high-spin and low-spin states.
  • Pristine Fephen shows a calculated SCO at 167 K, close to the experimental 175 K.
  • Fluorinated Fephen remains in the high-spin state across all computed temperatures.

Conclusions:

  • Fluorine substitution is a powerful tool to tune SCO behavior in Fephen complexes.
  • Computational methods accurately predict SCO transition temperatures and vibrational modes.
  • The study provides insights into the molecular mechanisms governing spin crossover phenomena.