On the relationship between corrosion inhibiting effect and molecular structure of 2,5-bis(n-pyndyl)-1,3,4-thiadiazole derivatives in acidic media Ac impedance and DFT studies

The inhibition properties of 2 5-bis(n-pyridyl)-1 3 4-thiadiazoles (n-PTH) on corrosion of mild steel in different acidic media (1 M HCI 05 M H2SO4 and 1 M HCIO4) were analyzed by electrochemical impedance spectroscopy (EIS) The n-PTH derivatives exhibit good inhibition properties in different acidic solutions and the calculated values of Delta G degrees(ads) revealed that the adsorption mechanism of n-PTH on steel surface is mainly due to chemisorption While in 1 M HCIO4 both 2-PTH and 4-PTH isomers stimulate the corrosion process especially at low concentrations Quantum chemical calculations using the density functional theory (DFT) were performed on n-PTH derivatives to determine the relationship between molecular structure and their inhibition efficiencies The results of the quantum chemical calculations and experimental inhibition efficiency were subjected to correlation analysis and indicate that the inhibition effects of n-PTH may be explained in terms of electronic properties (c) 2010 Elsevier Ltd All rights reserved