Araceli Espinoza-Vázquez, Francisco Javier Rodríguez-Gómez, Ivonne Karina Martínez-Cruz, Deyanira Ángeles Beltrán, Guillermo Enrique Negrón Silva, Manuel Eduardo Palomar Pardavé, Leticia Lomas Romero, Diego Pérez Martínez, Alejandra M. Navarrete-López

The design and synthesis of a series of theophylline derivatives containing 1,2,3-triazole moieties is presented. The
corrosion inhibition activities of these new triazole-theophylline compounds were evaluated by studying the
corrosion of API 5L X52 steel in 1 M HCl media. The results showed that an increase in the concentration of the
theophylline-triazole derivatives also increases the charge transference resistance (Rct) value, enhancing inhibition
efficiency and decreasing the corrosion process. The electrochemical impedance spectroscopy under static conditions
studies revealed that the best inhibition efficiencies (~90%) at 50 ppm are presented by the all- substituted
compounds. According to the Langmuir isotherm, the compounds 4 and 5 analyzed exhibit physisorptionchemisorption
process, with exception of the hydrogen 3, bromo 6 and iodo 7 substituted compound, which exhibit
chemisorption process. The corrosion when submerging a steel bar in 1 M HCl was studied using SEM-EDS. This
experiment showed that the corrosion process decreases considerably in the presence of 50 ppm of the organic
inhibitors. Finally, theoretical study showed a correlation between EHOMO, hardness (η), electrophilicity (W),
atomic charge and the inhibition efficiency in which the iodo 7 substituted compound presents the best inhibitor
behavior.