Theoretical and spectroscopic studies of a tricyclic antidepressant, imipramine hydrochloride

Sagdinc S. , AZKESKİN C., EŞME A.

JOURNAL OF MOLECULAR STRUCTURE, vol.1161, pp.169-184, 2018 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 1161
  • Publication Date: 2018
  • Doi Number: 10.1016/j.molstruc.2018.02.056
  • Page Numbers: pp.169-184
  • Keywords: Imipramine hydrochloride ([H-IMI]Cl), NLO, UV-Vis, PED, Vibrational analysis, MOLECULAR-STRUCTURE, FT-IR, STABILITY, RAMAN, NBO


Imipramine hydrochloride ([H-IMI]Cl), C19H24N2.HCl, is the prototypic tricyclic antidepressant (TCA) inhibitor of norepinephrine and serotonin neuronal reuptake. The molecular structure, molecular electrostatic potential (MEP), natural bond orbital (NBO) analysis, linear and non-linear optical (NLO) properties of [H-IMI]Cl have been investigated using the density functional theory (DFT) calculations with the B3LYP level at the 6-311++G(d,p) basis set. The UV-Vis spectra for [H-IMI]Cl were experimentally studied in water and methanol. TD-DFT calculations in water and methanol were employed to investigate the absorption wavelengths (A), excitation energies (E), and oscillator strengths (j) for the UV-Vis analysis and the major contributions to the electronic transitions. From NBO analysis, the orbitals with the stabilization energy E(2) of 192.15 kcal/mol are pi*(C5-C18) as donor NBO and pi*(C19-C20) as acceptor NBO. The FT-IR (4000-400 cm(-1)) and FT-Raman (3500-50 cm-1) spectra have been measured and analyzed. The assignment of bands observed vibrational spectra have been made by comparison of its calculated theoretical vibrational frequencies obtained using the DFT/B3LYP/6-311++G(d,p) method. The detailed vibrational assignments were performed with the DFT calculation, and the potential energy distribution (PED) of [H-IMI]Cl was obtained by the Vibrational Energy Distribution Analysis 4 (VEDA4) program. The scaled frequencies resulted in good agreement with the observed spectral patterns. (C) 2018 Elsevier B.V. All rights reserved.