Conformations of ribonucleoside uridine in the low temperature Ar matrices

The conformational equilibrium of the ribonucleoside uridine molecules in low-temperature Ar matrices was investigated by the FTIR matrix isolation spectroscopy and quantum-chemical calculations at the DFT and MP2 levels of theory. It was established that conformers with a carbonyl group C2O, which takes part in the intramolecular hydrogen bonds, dominate in the low temperature matrices. Populations of syn- and anti- conformers with intramolecular hydrogen bonds O5′H–O2 and O2′–O2, respectively, are equal practically. Unlike 2′-deoxyuridine, the syn- conformers of Ur with C3′-endo structure of the ribose ring (South) have been found in Ar matrices. At the same time the conformations of C2′-endo (North) ribose ring prevail both in anti- and syn- conformers.