Molecular simulation, vibrational spectroscopy and global reactivity descriptors of pseudoephedrine molecule in different phases and states

Abstract

The ground state molecular energy, vibrational frequencies and HOMO-LUMO analysis of the title compound have been calculated with density functional theory in the B3LYP/6-311 + G (d,p) basis set using Gaussian 09 W software. The FT-IR spectrum of pseudoephedrine has been computed in the gas phase and in the presence of solvent water both in neutral and anionic structures. The TED assignments of the vibrational spectra have been assigned in the selected intense region. On isotopic substitution of carbon atoms, the shifting of frequencies is distinctly observed. The reported values and HOMO-LUMO mappings reveal the possibility of different charge transfers occurring within the molecule. A MEP map is depicted and the Mulliken atomic charge is also calculated. The UV–Vis spectra have been illustrated and explained from the frontier molecular orbitals using a TD-DFT approach.

Keywords

• Vibrational frequencies
• HOMO-LUMO
• UV–Vis
• TD-DFT
• TED assignment
• MEP