The conformational structure of adenosine molecules, isolated in low-temperature Ar matrices

Abstract

FTIR spectra of adenosine (Ado) molecules, isolated in low-temperature matrices, are obtained in the infrared range of 3800–400 cm−1, with a resolution of 0.3. MP2 and DT/B3LYP quantum-mechanical methods are used to calculate the population of major structural Ado isomers. It is shown that Ado can withstand prolonged evaporation at a temperature of 465 K without thermal decomposition. The structure five major conformers that are fixed in Ar matrices at 6 K, are established. Ado anti-conformers with intramolecular hydrogen bonds O2′H-N3, are found. The population of these anti-conformers is more than one and a half times less than the syn-conformer population having the intramolecular hydrogen bond O5′H-N3. In low-temperature matrices, the majority of the dominant conformers are fixed with a C2′-endo ribose ring structure. Similar to 2′-deoxyadenosine (dA), Ado conformers with intramolecular hydrogen bonds O3′H-O5 or O5′H-O3 were not found.