Experimental spectroscopic (FTIR, FT-Raman, FT-NMR, UV–Visible) and DFT studies of 1-ethyl-1,4-dihydro-7-methyl-4oxo-1,8 napthyridine-3-carboxylic acids

Abstract

The solid phase FTIR and FT-Raman spectra of 1-ethyl-1,4-dihydro-7-methyl-4oxo-1,8 napthyridine-3-carboxylic acid (EDMONCA) have been recorded in the regions 4000–500 and 4000–400cm−1 respectively. The equilibrium geometry, harmonic vibrational frequencies have been investigated by DFT/B3LYP and B3PW91 methods with 6-311G (d,p) basis set. The different between the observed and scaled wave number values of most of the fundamental is very small. The assignments of the vibrational spectra have been carried out with the aid of normal coordinate analysis (NCA) following the scaled quantum mechanical force field methodology (SQMFFM). Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. UV–Visible spectrum of the compound was recorded and the electronic properties HOMO and LOMO energies were measured. The electric dipole moment (μD) and first hyperpolarizability (βtot) values of the investigated molecule were computed using ab initio quantum mechanical calculations. The calculated results also show that the EDMONCA molecule may have microscopic nonlinear optics (NLO) behavior with non-zero values. 1H and 13C NMR spectra were recorded and 1H and 13C nuclear magnetic resonance chemical shift of the molecule were calculated using the gauge independent atomic orbital (GIAO) method. Thermal stability of EDMONCA was studied by thermogravimetric analysis (TGA). Next Fukui function was calculated to explain the chemical selectivity or reactivity site in EDMONCA. Finally molecular electrostatic potential (MEP) and other molecular properties were performed.