Synthesis, spectrophotometric characterization and DFT computational study of a novel quinoline derivative, 2-amino-4-(2,4,6-trinitrophenylamino)-quinoline-3-carbonitrile

Abstract

A novel quinoline derivative, 2-amino-4-(2,4,6-trinitrophenylamino)-quinoline-3-carbonitrile (ATQC) has been synthesized through condensation reaction between 2,4-diaminoquinoline-4-carbonitrile (DAQC) with picric acid (PA) in methanol. It has been proven by elemental analysis that the reaction proceeded based on 1:1 stioichiometric ratio (DAQC:PA). Infrared spectra assert the formation of the investigated compound; its stability is based on the formation of hydrogen bonding NHO beside charge transfer interaction. In addition, both 1H NMR and 13C NMR spectra reconfirmed the formation of the new compound, including both charge and hydrogen bonding. The investigated reaction has been carried out in acetonitrile (AN), methanol (MeOH) and ethanol (EtOH) where it has been proceeded through 1:1 stoichiometric ratio concordant with elemental analysis. It recorded high stability constant from Bensie-Hildebrand equation in methanol relative to acetonitrile or ethanol. Computational analysis using density functional theory (DFT) at B3LYP/6-31G (d, p) basis set using Gaussian 09W software also, asserted the high stability of the new compound based on the formation of strong hydrogen bonding between NH and neighboring nitro group. Furthermore, the optimization energy, geometrical structures, orbital energies, energy gap were determined. Quantum chemical reactivity parameters, including electronegativity, hardness, softness, electrophilicity index and chemical potential were determined from HOMO and LUMO energies. Molecular electrostatic potential were computed where a charge transfer was evidenced from DAQC towards PA and the LUMO are located at the nitro groups of PA moiety. This situation was found to go in harmony with Mullikan atomic charges calculated at the same level of theory. A complete analysis of the experimental spectra (FT-IR, 1H NMR and UV–Vis) have been given with TD-DFT at the same basis set. A good consistency between experimental and theoretical calculations was found confirming that the applied basis set is the suitable one for the system under investigation.