| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1405780 | Journal of Molecular Structure | 2014 | 7 Pages |
•Conformation of 3-chlorosalicylic acid in an argon matrix was investigated.•Stabilization due to intramolecular hydrogen bonding was examined.•Conformational changes to less stable isomers were caused by UV irradiation.•Isomerization between less stable isomers occurred upon higher-energy irradiation.
Conformations and photoreaction pathways of 3-chlorosalicylic acid have been investigated by low-temperature matrix-isolation infrared spectroscopy with an aid of the density-functional-theory calculation. It was found that only one conformer having an intramolecular hydrogen bond of PhOH⋯OC in COOH existed in argon matrices after deposition before UV irradiation. Two less stable conformers were produced upon UV irradiation (λ > 330 nm); one has an intramolecular hydrogen bond of PhOH⋯OH in COOH, and the other has two intramolecular hydrogen bonds of COOH⋯OHPh and PhOH⋯Cl. Another conformational change between the less stable conformers was observed when the matrix was exposed to the shorter-wavelength UV light (λ > 290 nm) for 1 min following the 300-min longer-wavelength UV irradiation (λ > 330 nm). The photoreaction pathways due to the conformational changes were supported by a kinetic analysis using the IR absorbance changes of the photoproducts against the irradiation time.
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