Synthesis and characterization of 4-fluorobenzaldehyde thiosemicarbazone derivatives as corrosion inhibitors

In this paper, we report the syntheses, characterization and studies on the inhibition efficiency in mild steel acidic corrosion of 4-fluorobenzaldehyde thiosemicarbazone, Hfbt, 4-fluorobenzaldehyde 2-methylthiosemicarbazone, Me-fbt, and their Zn(II) complexes [Zn(fbt)(2)] and [Zn(Me-fbt)(2)]Cl-2. The ligands present a good degree of activity that can be assigned to their molecular planar shape and to the presence of electron lone pairs that can interact with metal orbitals. The two zinc complexes present diametrically opposite properties: [Zn(fbt)(2)] is by far less active than the ligands, while [Zn(Me-fbt)(2)]Cl-2 is the most efficient. Quantum chemical studies were carried out in an attempt to rationalize this behaviour. (C) 2015 Elsevier B.V. All rights reserved.