Laser Raman and infra-red spectra of biomolecule: 5-aminouracil

摘要

Laser Raman (200-4000 cm~(-1)) and IR (200-4000 cm~(-1)) spectra of 5-aminouracil were recorded in the region 200-4000 cm~(-1). Assuming a planar geometry and C_s point group symmetry, it has been possible to assign all the 36 (25a' +11a") normal modes of vibration for the first time. The two NH bonds of the NH_2 group appear to be equivalent as the NH_2 stretching frequencies satisfy the empirical relation proposed for the two equivalent NH bonds of the NH_2 group. The two NH_2 stretching frequencies are distinctly separated from the CH/NH ring stretching frequencies. A strong and sharp IR band at 3360 cm~(-1) could be identified as the anti-symmetric NH_2 mode whereas the band at 3290 cm~(-1) with smaller density could be identified as the symmetric NH_2 stretching mode. All other bands have also been assigned different fundamentals/overtones/combinations.