FTIR spectra and conformations of 2′-deoxyuridine in Kr matrices

Abstract

The Fourier transform infrared spectra in the range 4000–200cm−1 of pyrimidine nucleoside 2′-deoxyuridine (dU) are obtained in low-temperature inert Kr matrices. For the first time, instead of a usual flat mirror, a low-temperature, one-coordinate retroreflector is used as the matrix substrate. Owing to this, the matrix setup is insensitive to dip angle vibrations of the cryostat and is favorable to work with thinner matrix layers. Of two syn-conformers with dU_s1 and dU_s2 (stabilized by the intramolecular hydrogen bond O5′H…O2), only the dT_s2 conformer with C2′-endo structure of the ribose ring is uniquely quenched. The height of the interconversion barrier of the minor syn-conformer dU_s1 was estimated to be below 0.7kcal∕mole. It is shown that the energy relaxation of impurities in Kr is slower than in Ar matrices.