article · Next Materials
Corrosion caused by acidic environments presents a significant challenge for preserving copper surfaces. This research evaluated three synthetic pyranopyrazole derivatives, designated ANP, AFP, and ABP, as protective molecular films against sulphuric acid degradation. Electrochemical measurements demonstrated that all three compounds deliver concentration-dependent protection, reaching maximum inhibition efficiencies between 93.6 percent and 95.1 percent at a concentration of 1.0 millimolar. Performance followed the order of ABP, followed by AFP, and ANP. Detailed surface imaging confirmed that these molecules assemble into compact, resistive layers that significantly decrease surface degradation and roughness. Computational analyses revealed spontaneous adsorption driven by heteroatoms and aromatic electron systems interacting with copper surfaces. Ultimately, comparing nitro, fluoro, and bromo substitutions established clear structure-performance relationships to guide the future design of protective inhibitors for copper in acidic conditions.
Acidic degradation of copper components leads to costly industrial maintenance, material waste, and premature equipment failure. By identifying how distinct chemical substitutions influence protective film formation on metal surfaces, this study offers practical design guidelines for developing organic corrosion inhibitors. These insights allow industrial chemists to design more effective, low-dosage chemical additives that safeguard critical metallic infrastructure in aggressive chemical processing environments.
The findings could support the formulation of protective chemical additives for industrial operations involving copper in acidic environments, such as acid pickling and chemical cleaning. Likely commercial beneficiaries include speciality chemical manufacturers and industrial maintenance providers. Because the work is early-stage laboratory research combining electrochemical testing and computational modelling, extensive formulation development, safety profiling, and field testing in operational conditions are required before commercialisation can take place.
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Designing molecular interfaces capable of protecting metallic materials against acid-induced degradation remains an important challenge in materials engineering. In this study, The corrosion-inhibition performance of three previously synthesized pyrano[2,3- c ]pyrazole derivatives 6-amino-3-methyl-4-(2-nitrophenyl)-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile (ANP), 6-amino-4-(3-fluorophenyl)-3-methyl-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile (AFP) and 6-amino-4-(3-bromophenyl)-3-methyl-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile (ABP), was investigated for copper in 0.5 M H 2 SO 4 using electrochemical, surface, and computational approaches. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) measurements revealed concentration-dependent inhibition with maximum efficiencies of approximately 93.6% (ANP), 94.5% (AFP) and 95.1% (ABP) at only 1.0 mM. Nyquist/Bode analyses supported by equivalent-circuit fitting, indicated the formation of compact and resistive adsorbed films that restricted interfacial charge transfer. Surface characterization (SEM, AFM) confirmed a substantial reduction in surface damage and roughness, with the overall protective performance following the order ABP > AFP > ANP, consistent with electrochemical results. DFT, Fukui-function analysis, and molecular simulations identified the heteroatoms and aromatic π-systems as the main adsorption sites and revealed favorable adsorption configurations on Cu(111). The calculated Δ 𝐺 0 a d s values (−38.67 to −39.23 kJ mol −1 ) confirmed spontaneous adsorption involving strong physical and electrostatic interactions, with a possible donor–acceptor contribution. The novelty of this work lies in comparing nitro-, fluoro-, and bromo-substituted pyranopyrazoles under identical conditions to establish a structure–interface–performance relationship. ABP showed the best performance, providing practical guidance for designing inhibitors for copper protection in acidic media.
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DOI: 10.1016/j.nxmate.2026.103308
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