Quantum chemical and spectroscopic investigations of 5-aminoquinoline

The Fourier transform infrared (FTIR) and FT-Raman spectra of 5-aminoquinoline (5AQ) have been recorded in the range 4000–400 and 3500–100 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. 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by using the gauge independent atomic orbital (GIAO) method. UV–vis 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, chemical shifts and absorption wavelengths were compared with the experimental data of the molecule. The vibrational frequencies which were determined experimentally are compared with those obtained theoretically from ab initio HF and DFT-B3LYP gradient calculations employing the 6-31G** and 6-311++G** basis sets for optimized geometries of the compound. The interactions of NH–π and the influence of amino group on the skeletal modes are investigated.