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Updated: Jul 14, 2026
11:44
Synthesis and Structure Determination of µ-Conotoxin PIIIA Isomers with Different Disulfide Connectivities
Published on: October 2, 2018
Excited-state dynamics of a methyl-substituted cyclic disulfide
James Merrick1, Claire Vallance1, Adam Kirrander1
1Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, UK. adam.kirrander@chem.ox.ac.uk.
Physical Chemistry Chemical Physics : PCCP
|July 13, 2026
Summary
Methyl substitution in cyclic disulfides like 1,2-dithiane delays ring-closing and enhances thiyl radical recombination. This theoretical study uses simulations to explore these photodynamic effects.
Area of Science:
- Physical Chemistry
- Computational Chemistry
- Photochemistry
Background:
- Cyclic disulfides are important in biological systems and materials science.
- Understanding their photodynamics is crucial for controlling chemical reactions.
- Methyl substitution can significantly alter molecular properties and reactivity.
Purpose of the Study:
- To investigate the theoretical effects of methyl substitution on the photodynamics of 1,2-dithiane.
- To compare the excited-state dynamics of 1,2-dithiane and its dimethylated analogue.
- To predict observable experimental consequences of these dynamic changes.
Main Methods:
- Trajectory surface-hopping simulations initiated on the first excited state (S1).
- Comparison of electronic state populations and nuclear geometries over 1 picosecond.
- Disentanglement of steric and inertial effects in the substituted molecule.
- Computation of time-resolved valence photoelectron spectra using the Dyson norm approximation.
Main Results:
- A delayed ring-closing event was predicted for the dimethylated 1,2-dithiane after S-S bond homolysis.
- An enhanced quantum yield of thiyl radical recombination on the ground state was observed for the dimethylated system.
- Steric and inertial effects were analyzed to understand their influence on the dynamics.
Conclusions:
- Methyl substitution significantly impacts the photodynamics of 1,2-dithiane.
- The study provides theoretical insights into how structural modifications affect excited-state reaction pathways.
- Predicted spectral data can guide future experimental investigations of cyclic disulfide photochemistry.
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