Issue 42, 2018

Identification and composition of conformational isomers and their cations in crotonaldehyde by VUV-MATI spectroscopy

Abstract

Crotonaldehyde is a simple α,β-unsaturated aldehyde that reacts stereochemically with nucleophilic reagents according to its conformational structure. Identifiable vibrational spectra of the cationic crotonaldehyde conformers were measured using one-photon vacuum ultraviolet mass-analysed threshold ionization (VUV-MATI) spectroscopy. From the 0–0 bands for the individual conformers confirmed by Franck–Condon (FC) simulations, the precise adiabatic ionization energies were determined to be 9.7501 ± 0.0004 eV (78 640 ± 3 cm−1), 9.7620 ± 0.0004 eV (78 736 ± 3 cm−1), 9.7122 ± 0.0004 eV (78 334 ± 3 cm−1), and 9.6480 ± 0.0004 eV (77 816 ± 3 cm−1) for the trans-s-trans (tt)-, trans-s-cis (tc)-, cis-s-trans (ct)-, and cis-s-cis (cc)-crotonaldehyde, respectively. The complete vibrational assignments were accomplished for the peaks observed in the VUV-MATI spectrum from the calculated vibrational frequencies and the FC factors according to the dipole selection rules for one-photon absorption. In addition, the composition at ambient temperature was determined to be 1.000 (93.0%): 0.037 (3.4%): 0.036 (3.4%): 0.002 (0.2%) for the tt-/tc-/ct-/cc-conformers from the relative intensities of the 0–0 bands in the MATI spectrum normalized with the calculated dipole transition probabilities as proven by the NMR data for the trans- and cis-stereoisomers. This study ascertained the existence of the s-cis conformers of crotonaldehyde for the first time.

Graphical abstract: Identification and composition of conformational isomers and their cations in crotonaldehyde by VUV-MATI spectroscopy

Supplementary files

Article information

Article type
Paper
Submitted
03 Sep 2018
Accepted
10 Oct 2018
First published
10 Oct 2018

Phys. Chem. Chem. Phys., 2018,20, 27162-27168

Identification and composition of conformational isomers and their cations in crotonaldehyde by VUV-MATI spectroscopy

S. M. Park, H. L. Kim and C. H. Kwon, Phys. Chem. Chem. Phys., 2018, 20, 27162 DOI: 10.1039/C8CP05577G

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements