QUANTUM CHEMICAL STUDY OF CHLORO SUBSTITUENT’S POSITION ON QUINOLINE FOR INHIBITION OF ALUMINIUM CORROSION IN HYDROCHLORIC ACID SOLUTIONS

Journal: Acta Chemica Malaysia (ACMY)
Author:A.M. Usmana, A.A.Muhammad, Jamilu Ahmad Bello, Abdulrahman Muhammad Haris, Sulaiman Tijjani Nasiru
ISSN: 2576-6732
e-ISSN: 2576-6724

This is an open access journal distributed under the Creative Commons Attribution License CC BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited

DOI: 10.26480/acmy.01.2026.12.19

Quantum chemical study was carried out with the aid of material studio using density functional theory (DFT), which examined the effects of specific chloroquinoline molecules on the inhibition of aluminium corrosion in hydrochloric acid, as well as the effects of the chlorine substituent at positions 5, 6, and 8 of the core quinoline. Prior to optimization of each molecule, simulations were performed by means of the DFT electronic program DMol3 using the Mulliken population analysis in the Material Studio. DMol3 permitted the analysis of the electronic structures and energies of molecules, solids and surfaces. The analysis of the quantum chemical parameters, the adsorption parameters form the simulation of the molecules, the Mulliken and Hirshfeld values of the fukui indices for the three molecules of the 5-ClQ, 6-ClQ and 8-ClQ indicated that all the three molecules exhibits high potential for inhibition of aluminium corrosion in HCl environment. The most popular parameters which play a prominent role were the eigen values of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), the HOMO-LUMO gap (ΔE), chemical hardness and softness, electro-negativity and the number of electrons transferred from inhibitor molecule to the metal surface. All the molecules showed good corrosion inhibition tendency, however, 5-ClQ molecule gives better aluminium corrosion inhibition potential than other two molecules. The orientation of the chlorine substituent on the core quinoline was found to be responsible for intra-molecular intraction which leads to reduced attraction to the aluminium surface for the 6-ClQ and 8-ClQ molecules, hence lower corrosion inhibition tendency than 5-ClQ molecule despite having the same molecular mass.