کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1404495 | 1501911 | 2006 | 8 صفحه PDF | دانلود رایگان |

Three structural isomers of pyridinecarboxaldehydes (2-, 3- and 4-pyridinecarboxaldehyde) have been investigated in detail with matrix-isolation infrared spectroscopy in the 3000–600 cm−1 region, combined with the UV photo-excitation and density-functional theory (DFT) calculations. Two rotamers (anti and syn) for 2- and 3-pyridinecarboxaldehyde (2- and 3-PCA, respectively) and one rotamer for 4-pyridinecarboxaldehyde (4-PCA) were identified upon photo-excitation. Most of the observed bands of each rotamer have been assigned. Both the infrared data and the results of the DFT calculations agree that the syn rotamer is a less stable isomer for 2- and 3-PCA. Formation of an intramolecular CH⋯N hydrogen bond in the anti rotamer of 2-PCA results in a shortening of the aldehyde CH bond length. The CO bond length is shortened in the syn rotamer due to the repulsion between the N and aldehyde O atoms. With 2-PCA, both photoinduced rotational isomerism and photolysis were observed upon UV irradiation.
Journal: Journal of Molecular Structure - Volume 825, Issues 1–3, 15 December 2006, Pages 143–150