Characterization (FT-Raman, FT-IR Spectra) of 3.5-Dimethoxybenzaldehyde C9H10O3 and Compared with (DFT)

Abstract

In this work, both experimental and theoretical study on the FT-IR and Raman spectra of 3.5-dimethoxybenzaldehyde have been carried out. The FT-IR and FT-Raman spectra of the title compound have been recorded in the range of 4000–400 cm^-1 and 3500–50 cm^-1 respectively. The molecular geometry and vibrational frequencies in the ground state are calculated using the DFT method and assuming C_S symmetry. The infrared and Raman spectra were also predicted from the calculated intensities. Comparison of simulated spectra with the experimental spectra provides important information about the ability of the computational method to describe the vibrational modes. The agreement between the calculated and experimental frequencies is very good: always better than 97% for the observed skeletal vibrations. This compound is characterized by the presence of two methyl groups, which makes the attribution of their vibrational modes difficult because of the presence of the low frequency modes attributed to the torsion movements CH₃.