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

π Electron Effects on Chemical Shift: Overview01:27

π Electron Effects on Chemical Shift: Overview

1.6K
An applied magnetic field causes loosely bound π-electrons in organic molecules to circulate, producing a local or induced diamagnetic field over a large spatial volume. As the molecules tumble in solution, the field generated by π-electrons in spherical substituents results in a zero net field. However, the net field generated by π-electrons in non-spherical substituents is not zero. The effect of this induced field depends on the orientation of the molecule with respect to B0,...
1.6K
Electron Paramagnetic Resonance (EPR) Spectroscopy: Organic Radicals01:17

Electron Paramagnetic Resonance (EPR) Spectroscopy: Organic Radicals

3.3K
Ideally, an unpaired electron shows a single peak in the EPR spectrum due to the transition between the two spin energy states. However, coupling interactions can occur between the spins of the unpaired electron and any neighboring spin-active nuclei. This hyperfine coupling results in hyperfine splitting, where the EPR signal is split into multiplets. The signals split into 2nI + 1 peaks, where n is the number of equivalent nuclei and I is the nuclear spin. These splitting patterns provide...
3.3K
Energy Diagrams, Transition States, and Intermediates02:13

Energy Diagrams, Transition States, and Intermediates

20.0K
Free-energy diagrams, or reaction coordinate diagrams, are graphs showing the energy changes that occur during a chemical reaction. The reaction coordinate represented on the horizontal axis shows how far the reaction has progressed structurally. Positions along the x-axis close to the reactants have structures resembling the reactants, while positions close to the products resemble the products.  Peaks on the energy diagram represent stable structures with measurable lifetimes, while...
20.0K
Energy Associated With a Charge Distribution01:21

Energy Associated With a Charge Distribution

1.9K
The work done to bring a charge through a distance r is given by the potential difference between the initial and the final position. To assemble a collection of point charges, the total work done can be expressed in terms of the product of each pair of charges divided by their separation distance, defined with respect to a suitable origin. Solving this expression gives the energy stored in a point charge distribution.
1.9K
The Energies of Atomic Orbitals03:21

The Energies of Atomic Orbitals

29.9K
In an atom, the negatively charged electrons are attracted to the positively charged nucleus. In a multielectron atom, electron-electron repulsions are also observed. The attractive and repulsive forces are dependent on the distance between the particles, as well as the sign and magnitude of the charges on the individual particles. When the charges on the particles are opposite, they attract each other. If both particles have the same charge, they repel each other.
29.9K
Resonance and Hybrid Structures02:16

Resonance and Hybrid Structures

25.2K
According to the theory of resonance, if two or more Lewis structures with the same arrangement of atoms can be written for a molecule, ion, or radical, the actual distribution of electrons is an average of that shown by the various Lewis structures.
Resonance Structures and Resonance Hybrids
The Lewis structure of a nitrite anion (NO2−) may actually be drawn in two different ways, distinguished by the locations of the N–O and N=O bonds.
25.2K

You might also read

Related Articles

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

Sort by
Same author

Targeting Bothrops asper venom enzymes: Steroidal derivatives as potential inhibitors of phospholipase A<sub>2</sub> and serine proteinases.

Bioorganic chemistry·2026
Same author

A simple definition of the number of excited electrons.

Physical chemistry chemical physics : PCCP·2026
Same author

Photochemical Rearrangements of Pyridine N-Oxides: Pathways to Oxaziridine Derivatives.

Molecules (Basel, Switzerland)·2025
Same author

From BN-Dewar benzene to BN-benzvalene: a computational exploration of photoisomerization mechanisms.

Organic & biomolecular chemistry·2025
Same author

Mechanistic insights on the Lewis acid-catalyzed three-component cationic Povarov reaction: synthesis of <i>N</i>-propargyl 1,2,3,4-tetrahydroquinolines.

RSC advances·2025

Related Experiment Video

Updated: Jan 16, 2026

Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids
08:04

Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids

Published on: May 27, 2020

8.9K

Electron Density Redistribution as a Descriptor for Excited-State Reactivity.

Cristian J Guerra1

  • 1Facultad de Ciencias Exactas, Departamento de Ciencias Químicas, Laboratorio de Síntesis y Reactividad de Compuestos Orgánicos, Universidad Andrés Bello, República 275, Santiago 8370146, Chile.

The Journal of Physical Chemistry. A
|September 25, 2025
PubMed
Summary

This study introduces the electronic redistribution function to analyze excited-state reactivity in photochemical reactions. This method identifies reactive sites by quantifying electron density changes, aiding in understanding photoproduct formation.

More Related Videos

Author Spotlight: Magnetometric Characterization of Intermediates in the Solid-State Electrochemistry of Redox-Active Metal-Organic Frameworks
06:53

Author Spotlight: Magnetometric Characterization of Intermediates in the Solid-State Electrochemistry of Redox-Active Metal-Organic Frameworks

Published on: June 9, 2023

2.6K
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

Related Experiment Videos

Last Updated: Jan 16, 2026

Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids
08:04

Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids

Published on: May 27, 2020

8.9K
Author Spotlight: Magnetometric Characterization of Intermediates in the Solid-State Electrochemistry of Redox-Active Metal-Organic Frameworks
06:53

Author Spotlight: Magnetometric Characterization of Intermediates in the Solid-State Electrochemistry of Redox-Active Metal-Organic Frameworks

Published on: June 9, 2023

2.6K
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

Area of Science:

  • Computational Chemistry
  • Photochemistry
  • Quantum Chemistry

Background:

  • Understanding excited-state reactivity is crucial for photochemical processes.
  • Existing methods may not fully capture dynamic electron density changes.
  • The Quantum Theory of Atoms in Molecules (QTAIM) provides a framework for analyzing molecular properties.

Purpose of the Study:

  • To introduce and validate the electronic redistribution function, Δρij(r), as a descriptor for excited-state reactivity.
  • To quantify electron density changes between electronic states and identify reactive sites.
  • To apply the descriptor to various photochemical reactions and analyze conical intersection regions.

Main Methods:

  • Utilizing the Quantum Theory of Atoms in Molecules (QTAIM).
  • Employing state-specific density partitioning.
  • Calculating the electronic redistribution function, Δρij(r), with state weights (ci^2, cj^2).
  • Applying the method to diverse photochemical systems including cycloadditions and photocyclizations.

Main Results:

  • The Δρij(r) descriptor effectively quantifies electron density redistribution between electronic states.
  • It successfully identifies charge depletion (δ+) and accumulation (δ-) sites, predicting reaction pathways.
  • Distinct reactivity patterns were observed in systems like ethylene [2+2] cycloaddition and Paternò-Büchi reactions.
  • Analysis of conical intersection regions provided insights into bond-forming mechanisms.

Conclusions:

  • The electronic redistribution function, Δρij(r), is a valuable tool for analyzing excited-state reactivity in photochemistry.
  • This method offers a physically meaningful interpretation of density differences and reactive site identification.
  • The framework provides new insights into reaction mechanisms, particularly at conical intersections.