Related Experiment Video
Updated: Feb 28, 2026
05:51
Isotopic Effect in Double Proton Transfer Process of Porphycene Investigated by Enhanced QM/MM Method
Published on: July 19, 2019
6.7K
Knockout driven fragmentation of porphyrins
Linda Giacomozzi1, Michael Gatchell, Nathalie de Ruette
1Department of Physics, Stockholm University, Stockholm, SE-106 91, Sweden. linda.giacomozzi@fysik.su.se.
Physical Chemistry Chemical Physics : PCCP
|June 20, 2017
Summary
Collisions between tetraphenylporphyrin cations and helium or neon atoms reveal that prompt atom knockout is a key factor in molecular destruction. This impulse-driven process generates reactive fragments, important for understanding molecular responses in this energy range.
Area of Science:
- Chemical Physics
- Molecular Dynamics
- Computational Chemistry
Background:
- Tetraphenylporphyrin cations are complex organic molecules.
- Understanding molecular fragmentation in ion-molecule collisions is crucial.
- Previous studies faced challenges in isolating specific fragmentation mechanisms.
Purpose of the Study:
- To investigate collisions between tetraphenylporphyrin cations and He/Ne.
- To elucidate the role of prompt atom knockout in molecular destruction.
- To analyze molecular response to impact using theoretical and simulation methods.
Main Methods:
- Experimental study of ion-molecule collisions at 50-110 eV center-of-mass energies.
- Density functional theory (DFT) calculations for dissociation energies.
- Classical molecular dynamics (MD) simulations of molecular response to impact.
Main Results:
- Prompt atom knockout significantly contributes to total destruction cross sections.
- Impulse-driven processes were identified as a major fragmentation pathway.
- Highly reactive molecular fragments are produced through this mechanism.
Conclusions:
- Prompt atom knockout is a critical mechanism in tetraphenylporphyrin cation fragmentation by He/Ne.
- This process is likely important for various molecular systems in the studied energy range.
- The findings provide a method for isolating impulse-driven fragmentation in biomolecular collisions.
![Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F60786.jpg&w=3840&q=50)
Related Concept Videos
01:20Mass Spectrometry: Molecular Fragmentation Overview
5.9K
The ionization of a molecule into a molecular ion inside the mass spectrometer causes instability in the molecule's structure due to the loss of an electron. This eventually leads to the fragmentation or breaking of some bonds in the molecule. The fragmentation occurs predominantly at specific bonds to yield relatively stable fragments.
One type of fragmentation pattern is the cleavage of a single bond in the molecular ion. The cleavage leads to a radical and a cation. The cleavage can occur at...
One type of fragmentation pattern is the cleavage of a single bond in the molecular ion. The cleavage leads to a radical and a cation. The cleavage can occur at...
5.9K
00:54Radical Formation: Homolysis
4.5K
A bond is formed between two atoms by sharing two electrons. When this bond is broken by supplying sufficient energy, either two electrons can be taken up by one atom forming ions by the cleavage called heterolysis, or the two electrons are shared by two atoms, with one each creating radicals by the cleavage called homolysis.
4.5K
01:17Oxidation of Phenols to Quinones
5.0K
In the presence of oxidizing agents, phenols are oxidized to quinones. Quinones can be easily reduced back to phenols using mild reducing agents. The electron-donating hydroxyl group enhances the reactivity of the aromatic ring, enabling oxidation of the ring even in the absence of an α hydrogen.
o-hydroxy phenols are oxidized to o-quinones and p-hydroxy phenols to p-quinones. Such redox reactions involve the transfer of two electrons and two protons. The reversible redox...
o-hydroxy phenols are oxidized to o-quinones and p-hydroxy phenols to p-quinones. Such redox reactions involve the transfer of two electrons and two protons. The reversible redox...
5.0K
01:11Nucleophilic Aromatic Substitution: Elimination–Addition
5.2K
Simple aryl halides do not react with nucleophiles. However, nucleophilic aromatic substitutions can be forced under certain conditions, such as high temperatures or strong bases. The mechanism of substitution under such conditions involves the highly unstable and reactive benzyne intermediate. Benzyne contains equivalent carbon centers at both ends of the triple bond, each of which is equally susceptible to nucleophilic attack. This 50–50 distribution of products is...
5.2K
00:53Mass Spectrometry: Alkyne Fragmentation
2.2K
The fragmentation of alkynes preferentially occurs at the carbon–carbon bond between the α and β carbon of the alkyne bond to generate a 3-propynyl cation (or propargyl cation). In terminal alkynes, there is the only type of fragmentation that yields the 3-propynyl cation. The unsubstituted 3-propynyl cation exhibits a peak at a mass-to-charge ratio of 39. In internal alkynes, the 3-propynyl cation is substituted. For example, 2-pentyne fragments into methyl-substituted 3-propynyl cation,...
2.2K
01:03Mass Spectrometry: Alcohol Fragmentation
4.7K
Alcohols (R-OH) ionize to lose one non-bonded electron from the oxygen atom, forming molecular ions. Due to their tendency to fragment rapidly, the intensity of the molecular ion peak in the mass spectrum is weak or sometimes absent. The fragmentation patterns for alcohols occur in two ways, i.e. ⍺-cleavage and dehydration. During ⍺-cleavage, the bond at the ⍺-position adjacent to the hydroxyl group cleaves to give a resonance-stabilized cation and a radical. However, intramolecular...
4.7K