6-Aminouracil: Geometries and spectra in the isolated state and in the solid state simulation. A comparison with 5-aminouracil

•The FT-IR and laser-Raman spectra of 6-aminouracil in the solid state was analyzed.•The crystal unit cell of the solid state was simulated through a tetramer form.•Linear scaling equations at the B3LYP and M062X DFT levels were presented.•The differences between 5-aminouracil and 6-aminouracil were established.

FT-IR and FT-Raman spectra of 6-aminouracil were recorded in the solid state in the regions 3500-0 cm−1 and 4000–400 cm−1, respectively. The unit cell reported by X-ray in the crystal was reproduced theoretically by density functional theoretical calculations as a tetramer form. To correct the overestimation of the theoretical wavenumbers of 6-aminouracil were used specific scaling equations determined from the molecule of uracil. These scaled frequencies obtained were employed in the reassignment of several Raman and Infrared experimental bands. In the comparison of these experimental values the percentage of error is very small in most of the wavenumbers. A correlation between the geometric parameters, charge distribution and vibrational spectra of 6-aminouracil and 5-aminouracil molecules was shown.

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