FTIR, FT-Raman, FT-NMR, ab initio and DFT electronic structure investigation on 8-chloroquinoline and 8-nitroquinoline

The Fourier transform infrared (FTIR) and FT-Raman spectra of 8-chloroquinoline (8CQ) and 8-nitroquinoline (8NQ) have been recorded in the range 4000-400 and 4000-100 cm−1, respectively. The complete vibrational assignment and analysis of the fundamental modes of the compounds were carried out using the observed FTIR and FT-Raman data. Ab initio and DFT calculations have been performed and the structural parameters of the compounds are determined from the optimized geometries with 6-31G∗∗, 6-311++G∗∗ and cc-pVTZ basis sets. 1H and 13C nuclear magnetic resonance chemical shifts of the molecule were calculated using the gauge independent atomic orbital (GIAO) method. Uv-visible spectrum of the compound was recorded and the electronic properties, such as HOMO and LUMO energies, were performed by time-dependent DFT (TD-DFT) approach. The geometric parameters, energies, harmonic vibrational frequencies, IR intensities, Raman activities chemical shifts and absorption wavelengths were compared with the experimental data of the molecule. The influence of chloro and nitro groups on the skeletal modes and on the proton chemical shifts have been investigated.