Issue 39, 2014

Transient UV pump–IR probe investigation of heterocyclic ring-opening dynamics in the solution phase: the role played by nσ* states in the photoinduced reactions of thiophenone and furanone

Abstract

The heterocyclic ring-opening dynamics of thiophenone and furanone dissolved in CH3CN have been probed by ultrafast transient infrared spectroscopy. Following irradiation at 267 nm (thiophenone) or 225 nm (furanone), prompt (τ < 1 ps) ring-opening is confirmed by the appearance of a characteristic antisymmetric ketene stretching feature around 2150 cm−1. The ring-opened product molecules are formed highly vibrationally excited, and cool subsequently on a ∼6.7 ps timescale. By monitoring the recovery of the parent (S0) bleach, it is found that ∼60% of the initially photoexcited thiophenone molecules reform the parent molecule, in stark contrast with the case in furanone where there is less than 10% parent bleach recovery. Complementary ab initio calculations of potential energy cuts along the S–C([double bond, length as m-dash]O) and O–C([double bond, length as m-dash]O) ring-opening coordinate reveals insights into the reaction mechanism, and the important role played by dissociative (n/π)σ* states in the UV-induced photochemistry of such heterocyclic systems.

Graphical abstract: Transient UV pump–IR probe investigation of heterocyclic ring-opening dynamics in the solution phase: the role played by nσ* states in the photoinduced reactions of thiophenone and furanone

Supplementary files

Article information

Article type
Paper
Submitted
15 Aug 2014
Accepted
20 Aug 2014
First published
20 Aug 2014
This article is Open Access
Creative Commons BY license

Phys. Chem. Chem. Phys., 2014,16, 21271-21279

Transient UV pump–IR probe investigation of heterocyclic ring-opening dynamics in the solution phase: the role played by nσ* states in the photoinduced reactions of thiophenone and furanone

D. Murdock, S. J. Harris, J. Luke, M. P. Grubb, A. J. Orr-Ewing and M. N. R. Ashfold, Phys. Chem. Chem. Phys., 2014, 16, 21271 DOI: 10.1039/C4CP03653K

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