Density functional theory and vibrational studies of mianserin and its hydrochloride and hydrobromide salts

The molecular structure, linear and non-linear optical properties, and electronic properties of the anti-depressant drug mianserin (MIA) and its salts (MIA HCl and MIA HBr) have been investigated using the density functional theory (DFT/B3LYP) method with a 6-311G(d,p) basis set. The calculated first hyperpolarizability values are comparable with the reported values and are attractive objects for future studies of non-linear optics. FT-IR (4000–400 cm−1) and FT-Raman (3500–50 cm−1) spectra of mianserin HCl have been measured and analyzed. The assignment of bands observed in vibrational spectra have been made by comparison of their theoretical vibrational frequencies obtained using a B3LYP/6-311G(d,p) basis set. The scaled frequencies resulted in good agreement with the observed spectral patterns.