Skip to content

Femtosecond to Microsecond Observation of the Photochemical Reaction of 1,2-di(quinolin-2-yl)disulfide with Methyl Methacrylate

Research output: Contribution to journalArticle

Original languageEnglish
Pages (from-to)12981-12991
Number of pages11
JournalPhysical Chemistry Chemical Physics
Issue number20
Early online date3 May 2017
DateAccepted/In press - 3 May 2017
DateE-pub ahead of print - 3 May 2017
DatePublished (current) - 28 May 2017


The mechanism of the thiol-ene reaction induced by 330-nm ultraviolet excitation of 1,2-di(quinolin-2-yl)disulfide (QSSQ) in the presence of methyl methacrylate (MMA) is investigated by sub-picosecond to microsecond transient absorption spectroscopy. The measurements, spanning more than seven orders of magnitude of time, directly reveal multiple radical reaction steps. The ground state quinoliene-2-thiyl radical (QS) is formed with a time constant of ~200 fs by photolysis of QSSQ, followed by (64 ± 1)% decay of the initially formed QS radical because of solvent cage induced geminate recombination and QS dimer formation with a rate coefficient of (3.4 ± 0.2) × 1010 M-1 s-1 in methanol solution. In MMA solution, the carbon centered radical QS-MMA forms with a bimolecular reaction rate coefficient of (2.8 ± 0.2) × 107 M-1 s-1. The distinct infrared band at 1653 cm-1 assigned to the C=O stretch mode of the QS-MMA radical decays rapidly in aerated solution, in contrast to observations in a solution purged of O2 by N2 bubbling. This decay is attributed to reaction of the QS-MMA radicals with molecular oxygen, producing peroxy radicals. Kinetic analysis of the intensity of the band at 1653 cm-1 reveals a bimolecular reaction rate coefficient of (3.3 ± 0.3) × 109 M-1 s-1 for the reaction of the QS-MMA radicals with molecular oxygen, and indicates that this reaction step is reversible.

Download statistics

No data available



  • Full-text PDF (accepted author manuscript)

    Rights statement: This is the author accepted manuscript (AAM). The final published version (version of record) is available online via RSC at!divAbstract. Please refer to any applicable terms of use of the publisher

    Accepted author manuscript, 1 MB, PDF document


View research connections

Related faculties, schools or groups