Normal co-ordinate analysis, molecular structural, non-linear optical, second order perturbation studies of Tizanidine by density functional theory

•In this work, the experimental and theoretical spectra of 5CDIBTA are studied.•The complete assignments are performed on the basis of the potential energy distribution (PED).•Hyperpolarizabilities and HOMO–LUMO energies were performed by DFT approach.•Thermodynamic properties at different temperatures have been calculated in gas phase.

The spectroscopic techniques and semi-empirical molecular calculations have been utilized to analyze the drug Tizanidine (5CDIBTA). The solid phase Fourier Transform Infrared (FTIR) and Fourier Transform Raman (FTR) spectral analysis of 5CDIBTA is carried out along with density functional theory (DFT) calculations (B3LYP) with the 6-311++G(d,p) basis set. Detailed interpretation of the vibrational spectra of the compound has been made on the basis of the calculated potential energy distribution (PED). The individual atomic charges by NPA using B3LYP method is studied. A study on the Mulliken atomic charges, frontier molecular orbitals (HOMO–LUMO), molecular electrostatic potential (MEP) and thermodynamic properties were performed. The electric dipole moment (μ) and the first hyperpolarizability (α) values of the investigated molecule were also computed.

Graphical abstractThe Fourier Transform Infrared and Raman spectra of 5-chloro-N-(4,5-dihydro-1H-imidazol-2-yl)-2,1,3-benzothiadiazol-4-amine are recorded in solid phase, the harmonic vibrational frequencies, infrared intensities, Raman activities, bond length, bond angle are calculated by DFT methods using 6-311++G(d,p) basis set. To predict reactive sites for electrophilic and nucleophilic attack for the title molecule, molecular electrostatic potential (MEP) at the B3LYP/6-311++G(d,p) optimized geometry is calculated.Figure optionsDownload full-size imageDownload as PowerPoint slide