Experimental study, molecular docking, and quantum chemical investigation of a piperidinyl-acetamide derivative as a steel corrosion inhibitor

A new piperidinyl-acetamide derivative, N-(4-fluorophenyl)-2-(piperidin-1-yl)acetamide (IM4), was synthesised and characterised using FT-IR, NMR and mass spectrometry. This corrosion inhibition performance of carbon steel in 1M HCl was investigated by potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), surface analyses (SEM-EDS, AFM and contact angle measurements), density functional theory (DFT) and molecular dynamics simulation (MDS). In silico antimicrobial activity and molecular docking studies were also carried out using Escherichia coli (1T9U), Pseudomonas aeruginosa PAO1 (2UV0) and Aspergillus niger phytase (3K4P). Electrochemical results showed that the excellent inhibition efficiencies obtained were 95.8% (EIS) and 95.2% (PDP) at 10−3 M. The charge-transfer resistance increased from 21.57 to 512.6 Ω cm−2 while the corrosion current density decreased from 1104.1 to 35.1 μA/cm−2. By using PDP measurements, it was found that IM4 is a mixed-type inhibitor. The adsorption was of Langmuirian type and mostly chemisorptive. The results of the surface characterisation verified the presence of a protecting film on the steel surface and DFT and MDS calculations corroborated the experimental results. In addition, SEM-EDS and AFM showed that the surface of the materials is smoother and more hydrophobic when IM4 is present. The docking results indicated good interactions between IM4 and the targeted microorganisms.