Conformational structures and vibrational spectra of isolated pyrimidine nucleosides: Fourier transform infrared matrix isolation study of 2-deoxyuridine.

The conformational structures of 2-deoxyuridine (dU) were investigated using Fourier transform infrared (FTIR) matrix isolation spectroscopy. For the first time the FTIR spectra of dU in Ar matrices were obtained in the range 4000-200 cm(-1). The stabilities of conformers were estimated by the methods HF/3-21G (p), HF/6-31G (d,p) and MP2/6-31G (d,p).

[Conformational analysis of 5-substituted uracil].

The high-resolution IR-spectra of 5-nitrouracil and 5-bromouracil isolated in Ar matrices at 11 K were obtained for the first time. The conformational structure of uracil 5-substituents--thymine, 5-bromouracil, 5-nitrouracil--is calculated by the molecular mechanics and quantum--chemical MINDO/3 methods. The possibility of thymine transition to nonplanar conformations is observed.

[Infrared spectra of associated and hydrated pyrimidine bases of nucleic acids in argon matrix].

The spectral characteristics of interacting pyrimidine bases of nucleic acids--cytosine, 1-methylcytosine, uracil in autoassociates and hydrates--are investigated using the high-resolution infrared spectroscopy in argon matrices. Shifts of vibration frequencies in simple complexes are stated to be from 10 to 30 cm-1 in the 4000-400 cm-1 region observed. The isolated state-solid phase transition is followed by the absorption maximum shift, the latter being some hundreds of cm-1 in the 4000-2000 cm-1 region and some tens of cm-1 in the 1800-400 cm-1 region.

[Structure and physicochemical properties of isolated molecules of reumycin].

IR and electron spectra of an uracil derivative (antitumor antibiotic reumycin) were studied by low temperature spectroscopy. The experimental data corresponded to the quantum chemistry calculations of electron transmission. On the basis of the spectra interpretation the molecular structure of the reumycin isolated molecules was suggested.