FT-Raman and FTIR-ATR spectroscopies and DFT calculations of triterpene acetyl aleuritolic acid

Triterpenoids comprise an important class of compounds presenting a wide range of biologically important properties. Acetyl aleutitolic acid (AAA) is a triterpenoid isolated from Croton zehntneri, with molecular formula C32H50O4. Its structure has been characterized by NMR spectroscopy, however, there are no papers available regarding its vibrational properties. The Fourier-Transform Infrared with Attenuated Total Reflectance and Fourier-Transform Raman spectra, together with Density Functional Theory calculations of AAA are reported. Vibrational spectra were recorded at 300 K in the regions 600 cm−1 to 4000 cm−1 and 40 cm−1 to 4000 cm−1, for IR and Raman, respectively. Vibrational wavenumbers were predicted using Density Functional Theory calculations with the hybrid functional B3LYP and the basis set 6-31 G(d,p). A complete assignment of vibrational modes is given.