[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.

[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.