Discovery of Molecular Properties of a Quinoline Derivative via Benchmarking DFT Methods with Respect to Functional and Basis Set

The energetic, reactivity and spectroscopic characteristics of 2-choloro-6,8-dimethylquinoline-3-carboxaldehyde (2C68DMQCALD) molecule have been performed using experimental and theoretical methodologies. The discovery of molecular properties of the molecule has been tested via benchmarking the performance of density functional theory with regard to various functionals and basis sets. For DFT calculations, optimized parameters are proposed for B3LYP, BVP86, B3PW91, PBEPBE and BLYP functionals and STO–3G, DGDZVP, 6–311G, 6–311 + G(2d) and 6–311 + G(d, p) basis sets. The performance of the different DFT methods is compared to experimental data to determine the best and worst combinations. The study demonstrates that B3LYP/6–311 + G(2d) performs better than the other combinations. The calculated parameters such as the bond lengths, total energies, binding energies, energy gaps, harmonic vibrational frequencies of the normal modes, FT-IR spectra, thermodynamic and reactivity properties are discussed for each functional and basis set. Finally, it can be concluded that the choice of appropriate functional and basis set is important to obtain highly accurate results when compared to experimental data.