AN EXPERIMENTAL AND THEORETICAL HF and DFT INVESTIGATION OF CERTAIN BIOMEDICALLY ACTIVE COMPOUNDS

Abstract

In the present work, the complete molecular dynamics and properties of the six industrially newlineand biologically significant organic compounds, were carried out experimentally using the newlineobserved Fourier Transform Infrared (FT-IR), Fourier Transform Raman, and Fourier newlineTransform Nuclear Magnetic Resonance (FT NMR) spectral data and theoretically using newlineGaussian package based on quantum principle. All the parameters and data evolved newlineexperimentally were compared with the theoretically determined. The optimized structural newlineparameter such as bond lengths and bond angles were calculated. Vibrational analysis, newlineInterpretation of atomic, natural charges and Nonlinear Optical (NLO) property and Natural newlinebond orbital (NBO) analysis were performed. The calculated Highest Occupied Molecular newlineOrbital( HOMO), Lowest Unoccupied Molecular Orbital (LUMO) and frontier orbital energy newlinegap values along with their 3D plot were presented so as to enable better understanding of newlinecharge transfer occur within the molecule. The molecular electrostatic potentials of the newlinemolecules were constructed and the electrophilic and nucleophilic attacking sites of the newlinemolecules were determined. Ultra Violet-Visible (UV-VIS) spectral analyses on some newlinecomplicated molecules of pentane, benzene and pyridine derivatives have been researched by newlinetheoretical calculations. Also, In order to understand electronic transitions of the compound, newlineTime-dependent self-consistent field (TD-SCF) calculations on the calculated frontier orbital newlineenergies, absorption wavelengths (and#955;), oscillator strengths ( f) and excitation energies (E) for newlinegas phase and solvent (dimethyl sulfoxide (DMSO) and Chloroform) are also illustrated for newlinebenzene, pentane and pyridine derivatives. The 1H and 13C Nuclear Magnetic Resonance newline(NMR) chemical shifts of the molecule were calculated by gauge independent atomic orbital newline(GIAO) method and compared with experimental chemical shift.