Computational study of inhibitory effect of urea, n‐allylthiourea, thiosemicarbazide, and phenylhydrazine on the aluminum surfaces

• Published in: Materials and corrosion 2019-09, Vol.70 (9), p.1715-1725
• Main Authors: Zeidabadinejad, Leila, Hosseini, Seyyed Mohammad Ali
• Format: Article
• Language: English
• Subjects: Allylthiourea; Aluminum; Atomic properties; Charge transfer; Critical point; Gibbs free energy; inhibitor; Inhibitors; NBO; QTAIM; Quantum theory; Thiosemicarbazides; Ureas; Vapor phases; Water
• ISSN: 0947-5117; 1521-4176
• DOI: 10.1002/maco.201910789

The interactions between urea, n‐allylthiourea, thiosemicarbazide, and phenylhydrazine on the aluminum surface have been analyzed employing B3LYP/6‐31g(d,p) level of theory in liquid water and gas phase. The interaction energies for two orientations of urea, n‐allylthiourea, thiosemicarbazide, and phenylhydrazine were considered. The calculations revealed that in all cases the urea, n‐allylthiourea, thiosemicarbazide, and phenylhydrazine are located parallel to the Al surface. The preferred complex orientation is that one, in which the maximum number of donor atoms of inhibitors have interacted with the Al surface. The thermodynamic descriptor such as the Gibbs free energy of the complexes of inhibitors with the Al surface has been evaluated. The natural bond orbital analysis of inhibitors complexes with the Al surface was done to find out how to transfer the charge and compare the stability of the interactions. The localized orbital locator, electron location function and analysis and quantum theory of atoms in the molecule have been used to investigate the nature of the various possible interactions between inhibitors with Al surface in terms of bond critical points. The quantum theory of atoms in the molecule (QTAIM) method and localized orbital locator, electron location function have been utilized to explore the nature of various possible interactions between Inhibitors with Al atoms in terms of bond critical points (BCPs). Highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) and atomic charges studies show charge transfer occurs between inhibitors and Al surface. This behavior has been also investigated via QTAIM charge analysis.