A series of novel 1-N-α-d-glucopyranosyl-1H-1,2,3-triazole xanthines was synthesized from azido sugars (glucose, galactose, and lactose) and propargyl xanthines (theophylline and theobromine) using a typical copper (I)-catalyzed azide–alkyne 1,3-dipolar cycloaddition. The corrosion inhibition activities of these new carbohydrate-xanthine compounds were evaluated by studying the corrosion of API 5 L X70 steel in a 1 M HCl medium. The results showed that, at 10 ppm, a 90% inhibition efficiency was reached by electrochemical impedance spectroscopy. The inhibitory efficiency of these molecules is explained by means of quantum chemical calculations of the protonated species with the solvent effect, which seems to better represent the actual situation of the experimental conditions. Some quantum chemical parameters were analyzed to characterize the inhibition performance of the tested molecules.

A new tetracyclic morpholine-fused[5,1-c]-triazole, (4aS,5S,6aR,10aR,10bR)-5-methoxy-9,9-dimethyl-4a,5,6a,7,10a,10b-hexahydro-12H-[1,3]dioxino[4′,5′:5,6]pyrano[4,3-b][1,2,3]triazolo[1,5-d][1,4]oxazine, was synthesized via a five-step sequence starting from methyl α-_D-glucopyranoside by using, as a key step, an intramolecular copper(I) catalyzed alkyne-azide cycloaddition (CuAAC). The synthesized compound was fully characterized by ¹H and ¹³C NMR, FT-IR, and HRMS.

2-mercaptobenzimidazole (2-MBI) and propargyl-functionalized MBI (propargyl-MBI) as corrosion inhibitors for API 5L X70 steel in CO₂-saturated NaCl solution was evaluated using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), gravimetric weight loss, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS), and atomic force microscopy (AFM). Electrochemical tests showed that both inhibitors reduced corrosion, with propargyl-MBI exhibiting the best inhibition. propargyl-MBI achieving efficiencies of 96.1% by EIS and 97.4% by polarization at 10 ppm. After 96 h, corrosion rates decreased from 2.23 mm·year⁻¹ (blank) to 0.40 and 0.14 mm·year⁻¹ for 2-MBI and propargyl-MBI, respectively. SEM/EDS and AFM confirmed improved surface protection, with roughness decreasing from 142 nm (blank) to 76.8 nm (2-MBI) and 51.1 nm (propargyl-MBI). Adsorption followed the Langmuir model (R² = 0.99), with ΔG°ads values of −25.1 and −34.25 kJ·mol⁻¹ for 2-MBI and propargyl-MBI, respectively, indicating stronger adsorption after functionalization. Dispersion-corrected density functional theory calculations were used to elucidate the adsorption modes as well as the main interactions between the 2-MBI, in thiol and thione tautomers, and propargyl-MBI. The binding energy as well as the charge transfer were increased in the case of propargyl-MBI.

A new tetracyclic morpholine-fused [5,1-c]-triazole, (4aS,5S,6aR,10aR,10bR)-5-methoxy-9,9-dimethyl-4a,5,6a,7,10a,10b-hexahydro-12H-[1,3]dioxino[4',5':5,6]pyrano[4,3-b][1,2,3]triazolo[1,5-d][1,4]oxazine, was synthesized via a five-step sequence starting from methyl α-D-glucopyranoside by using as a key step an intramolecular copper(I) cat-alyzed alkyne-azide cycloaddition (CuAAC). The synthesized compound was fully characterized by 1H and 13C NMR, FT-IR, and HRMS.