The conformational equilibrium of thymidine and deuterothymidine molecules in lowerature Ar matrices has been studied using lowerature 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 lowerature 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 νN3D stretching vibration is split by the Fermi resonance.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)