Through our present study, three novel Gemini-fluorinated cationic surfactants bearing
different spacers (FSG6-2, FSG6-4, and FSG6-6) were synthesized, and their structures were explained
via different spectroscopic instruments such as 1H, 13C, and 19F NMR spectra. The surface activity
of the as-prepared surfactants was examined. The inhibiting influence of FSG6 molecules on the
X60 steel corrosion in the pickling solution (HCl) was examined by diverse methods comprising
electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), and X-ray
photoelectron spectroscopy (XPS) experimentations, and computational calculations. The inhibition
effectiveness of FSG6 surfactants followed the order of 93.37% (FSG6-2) < 96.74% (FSG6-4) < 98.37%
(FSG6-6) at 2.0 × 10−4 M. The FSG6 surfactants function as mixed-type inhibitors, according to
PDP investigations. The H2O molecules that adsorbed on the steel interface were substituted with
surfactant molecules, and the surfactant’s inhibitory activity is likely caused by the improvement in
an adsorptive layer on the steel substrate, as specified by the EIS results. The Langmuir isotherm
describes the absorption of FSG6 molecules on the metal surface. The XPS investigations validate the
steel interface’s extremely protective nature. The mechanism of interaction between FSG6 molecules
with an X60-steel employing the DFT calculations and MC simulations methods was also examined
and discussed.