Nucleoside conformers in low-temperature argon matrices: Fourier transform IR spectroscopy of isolated thymidine and deuterothymidine molecules and quantum-mechanical calculations

The conformational equilibrium of thymidine and deuterothymidine molecules in low-temperature Ar matrices has been studied using low-temperature matrix-isolation Fourier IR spectroscopy and quantum-chemical calculations by the DFT/B3LYP and MP2 methods. It has been found that two anti-conformers ta2_0 and ta3_0 with different structures of the sugar ring, C2 '-endo and C3 '-endo, predominate in low-temperature matrices. In isolated state, each of these conformers has a few low-barrier satellites that can fully pass into more stable structures when a molecule enters the matrix. The main syn conformer ts2_0 is stabilized by an intramolecular hydrogen bond between the O5 ' H group of the sugar and the C2O group of the base (O5 ' HO2), while C2 '-endo is the predominant conformation of the deoxyribose ring. The considerably lower population of ts2_0 compared to the anti-conformers ta2_0, ta3_0 can be explained by the smaller population of satellite conformations. It has been shown that the absorption band of nu N3D stretching vibration is split by the Fermi resonance.National Academy of Sciences of Ukraine12 month embargo; published online: 27 September 2019This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu