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

Radicals: Electronic Structure and Geometry01:07

Radicals: Electronic Structure and Geometry

5.3K
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...
5.3K
Woodward–Hoffmann Selection Rules and Microscopic Reversibility01:34

Woodward–Hoffmann Selection Rules and Microscopic Reversibility

4.1K
Electrocyclic reactions, cycloadditions, and sigmatropic rearrangements are concerted pericyclic reactions that proceed via a cyclic transition state. These reactions are stereospecific and regioselective. The stereochemistry of the products depends on the symmetry characteristics of the interacting orbitals and the reaction conditions. Accordingly, pericyclic reactions are classified as either symmetry-allowed or symmetry-forbidden. Woodward and Hoffmann presented the selection criteria for...
4.1K
Structure of Porins01:21

Structure of Porins

4.0K
Mitochondria, chloroplasts, and gram-negative bacteria have transmembrane, beta-barrel proteins called porins to mediate the free diffusion of ions and metabolites across the membrane. Mitochondrial porin precursors contain conserved amino acid sequences called beta signals at their C-terminal. Beta signals have a  motif of PoXGXXHyXHy (Po-Polar, X-Any amino acid, G-Glycine, Hy-LargeHydrophobic), which are crucial for precursor recognition to initiate precursor assembly. Beta-barrel...
4.0K
Aromatic Hydrocarbon Cations: Structural Overview01:18

Aromatic Hydrocarbon Cations: Structural Overview

4.0K
Cycloheptatriene is a neutral monocyclic unsaturated hydrocarbon that consists of an odd number of carbon atoms and an intervening sp3 carbon in the ring. The three double bonds in the ring correspond to 6 π electrons, which is a Huckel number, and therefore satisfies the criteria of 4n + 2 π electrons. However, the intervening sp3 carbon disrupts the continuous overlap of p orbitals. As a result, cycloheptatriene is not aromatic.
Removing one hydrogen from the intervening CH2 group...
4.0K
¹H NMR of Conformationally Flexible Molecules: Temporal Resolution00:52

¹H NMR of Conformationally Flexible Molecules: Temporal Resolution

1.3K
At room temperature, the chair conformer of cyclohexane undergoes rapid ring flipping between two equivalent chair conformers at a rate of approximately 105 times per second. These two chair conformers are in equilibrium. The rapid ring flipping results in the interconversion of the axial proton to an equatorial proton and an equatorial to the axial proton. Such interconversions are too rapid and cannot be detected on the NMR timescale. Hence, the NMR spectrometer cannot distinguish between the...
1.3K
[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction01:16

[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction

12.7K
The Diels–Alder reaction is an example of a thermal pericyclic reaction between a conjugated diene and an alkene or alkyne, commonly referred to as a dienophile. The reaction involves a concerted movement of six π electrons, four from the diene and two from the dienophile, forming an unsaturated six-membered ring. As a result, these reactions are classified as [4+2] cycloadditions.
12.7K

You might also read

Related Articles

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

Sort by
Same author

4,4'- and 2,4'-Bis(olympicenyl)s: Antiferromagnetically Coupled Diradicals with Twisted Conformations.

Organic letters·2026
Same author

Aethrene: A Stable Polycyclic Aromatic Hydrocarbon With a Triplet Ground State.

Angewandte Chemie (International ed. in English)·2026
Same author

Molecular Nanocarbons with Diverse Connectivity and Topologies Enabled by Bismuth(III) Triflate-Mediated Benzannulation Reaction.

Accounts of chemical research·2026
Same author

π-Aggregation-free, fused perylene pentamers: synthesis, narrowband far-red to near-infrared emission, and chiroptical properties.

Chemical science·2026
Same author

DeepCodon: A deep learning codon-optimization model to enhance protein expression.

Biodesign research·2026
Same author

Rapid establishment of KRAS-driven bladder cancer initiation and immune escape models using genetically engineered mice and organoid approaches.

Frontiers in immunology·2026

Related Experiment Video

Updated: Feb 24, 2026

Synthesis of pH Dependent Pyrazole, Imidazole, and Isoindolone Dipyrrinone Fluorophores using a Claisen-Schmidt Condensation Approach
14:11

Synthesis of pH Dependent Pyrazole, Imidazole, and Isoindolone Dipyrrinone Fluorophores using a Claisen-Schmidt Condensation Approach

Published on: June 10, 2021

6.8K

Conformationally Flexible Bis(9-fluorenylidene)porphyrin Diradicaloids.

Hejian Zhang1, Hoa Phan1, Tun Seng Herng2

  • 1Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore, Singapore.

Angewandte Chemie (International Ed. in English)
|August 13, 2017
PubMed
Summary

A novel diradicaloid molecule (Por-Fl) exhibits a triplet diradical state upon heating. Metal coordination and protonation alter its geometry and electronic properties, revealing insights into flexible open-shell systems.

Keywords:
conformational changediradicaloidsmagnetic propertiesnickelporphyrinoids

More Related Videos

Line Shape Analysis of Dynamic NMR Spectra for Characterizing Coordination Sphere Rearrangements at a Chiral Rhenium Polyhydride Complex
10:52

Line Shape Analysis of Dynamic NMR Spectra for Characterizing Coordination Sphere Rearrangements at a Chiral Rhenium Polyhydride Complex

Published on: July 27, 2022

3.4K
Conventional BODIPY Conjugates for Live-Cell Super-Resolution Microscopy and Single-Molecule Tracking
07:49

Conventional BODIPY Conjugates for Live-Cell Super-Resolution Microscopy and Single-Molecule Tracking

Published on: June 8, 2020

8.8K

Related Experiment Videos

Last Updated: Feb 24, 2026

Synthesis of pH Dependent Pyrazole, Imidazole, and Isoindolone Dipyrrinone Fluorophores using a Claisen-Schmidt Condensation Approach
14:11

Synthesis of pH Dependent Pyrazole, Imidazole, and Isoindolone Dipyrrinone Fluorophores using a Claisen-Schmidt Condensation Approach

Published on: June 10, 2021

6.8K
Line Shape Analysis of Dynamic NMR Spectra for Characterizing Coordination Sphere Rearrangements at a Chiral Rhenium Polyhydride Complex
10:52

Line Shape Analysis of Dynamic NMR Spectra for Characterizing Coordination Sphere Rearrangements at a Chiral Rhenium Polyhydride Complex

Published on: July 27, 2022

3.4K
Conventional BODIPY Conjugates for Live-Cell Super-Resolution Microscopy and Single-Molecule Tracking
07:49

Conventional BODIPY Conjugates for Live-Cell Super-Resolution Microscopy and Single-Molecule Tracking

Published on: June 8, 2020

8.8K

Area of Science:

  • Materials Chemistry
  • Supramolecular Chemistry
  • Organic Electronics

Background:

  • Diradicaloids are molecules with significant diradical character, exhibiting unique electronic and magnetic properties.
  • Conformationally flexible porphyrin derivatives offer tunable properties for advanced applications.
  • Understanding the influence of external stimuli on diradicaloid systems is crucial for their design and utilization.

Purpose of the Study:

  • To synthesize and characterize a stable 5,10-bis(9-fluorenylidene)porphyrin (Por-Fl) diradicaloid.
  • To investigate the effects of thermal population, Ni(II) coordination, and protonation on the geometry and electronic structure of Por-Fl.
  • To elucidate the relationship between structural changes and observed physical properties, including magnetic behavior.

Main Methods:

  • Synthesis of the 5,10-bis(9-fluorenylidene)porphyrin (Por-Fl) diradicaloid.
  • Single crystal X-ray diffraction to determine molecular geometry.
  • Spectroscopic and magnetic measurements (e.g., SQUID) to probe electronic structure and paramagnetic properties.
  • Computational studies to analyze singlet-triplet gaps and conformational changes.

Main Results:

  • The synthesized Por-Fl diradicaloid possesses a quinoidal, saddle-shaped geometry in the solid state.
  • Thermal excitation induces a triplet diradical state in both solution and solid states, explaining paramagnetic properties and hysteresis.
  • Ni(II) coordination slightly reduces the singlet-triplet gap without significant conformational change.
  • Protonation dramatically alters the conformation while preserving a closed-shell electronic structure.

Conclusions:

  • The study demonstrates the significant impact of heat, metal coordination, and protonation on the geometry and diradical character of flexible diradicaloids.
  • Conformational flexibility plays a key role in tuning the electronic and magnetic properties of these open-shell singlet systems.
  • These findings provide valuable insights for the rational design of novel functional materials based on diradicaloid structures.