Molecular Structure, Vibrational Spectra, UV-Visible and NMR Spectral Analysis on Ranitidine Hydrochloride using AB Initio and DFT Methods

A systematic approach has been adopted for structural analysis of Ranitidine Hydrochloride by using FTIR, FT Raman and UV-Vis and NMR spectroscopic techniques. The vibrational analysis are aided by electronic structure calculations HF method and density functional methods (B3LYP) performed with 6-31G(d,p) basis set, with the observed FTIR and FT Raman data, complete vibrational band assignments and analysis of the fundamental modes of the compound are carried out. The UV absorption spectra of the title compound dissolved in methanol. Natural Bond Orbital analysis has been carried out to explain the charge transfer (or) delocalization of change due to the intra molecular interactions. The first order Hyperpolarizability ( o) of this novel molecular system and related properties ( , o , x) of Ranitidine hydrochloride are calculated using HF and DFT(B3LYP/61-31G(d,p)) methods . In addition the molecular electrostatic potential (MEP) have been investigated using theoretical calculations, the calculated HOMO, LUMO energies and max were determined by timedependent DFT (TD DFT) method. H and C NMR theoretical shifts of the molecule were calculated. The thermodynamic functions of the title molecule are also performed using DFT method. Thermodynamics properties and atomic charges were calculated using both Hartee Fock and density functional method using above the basis set and compared. KEYWORDS