ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Eco-friendly synthesis and characterization of new pyrazoline derivatives as corrosion inhibitors for carbon steel in a 1 M HCl: electrochemical, DFT and MD simulation studies

Youssef Youssefi, Nazih Asoufar, Lahcen Oucheikh, Omar Ou-ani, Ahmad Oubair, Driss Chebabe, El Houssine Mabrouk, and Mohamed Znini

Laboratory of Natural Substances & Synthesis and Molecular Dynamics, Faculty of Sciences and Techniques, Moulay Ismail University of Meknes, Errachidia, Morocco

E-mail: y.youssefi@edu.umi.ac.ma

Received: 1 October 2025  Accepted: 1 April 2026

Abstract:

The novelty of this work lies in the green synthesis and evaluation of the anticorrosive properties of two new pyrazoline-based heterocyclic systems, namely 1-(1,3-diphenyl-4, 5-dihydro-1H-pyrazol-5-yl)pyrrolidin-2-one (DDPP) and 1-(3-(2,4-dinitrophenyl)-1-phenyl-4,5-dihydro-1H-pyrazol-5-yl)pyrrolidin-2-one (NDPP), on carbon steel (CS) in 1 M HCl. These compounds were synthesized using an environmentally friendly ultrasound-assisted method, achieving yields ranging from 79 to 89%, and characterized by spectroscopic techniques (¹H NMR, ¹³C NMR and IR). The corrosion inhibition of these compounds was studied using electrochemical techniques, namely potentiodynamic polarization curves (PDP) and electrochemical impedance spectroscopy (EIS). The morphology of the steel surface was analyzed by scanning electron microscopy (SEM). The results obtained show that these synthesized pyrazoline significantly reduce the corrosion rate, reaching a maximum efficiency of 98.03% at a concentration of 10^− 3. The adsorption of DDPP and NDPP on the surface of carbon steel conforms to the Langmuir adsorption isotherm, including physisorption and chemisorption on the metal surface. In addition, theoretical studies have been carried out using Density Functional Theory (DFT), natural bonds orbital (NBO) and natural population analysis (NPA) to explain the interaction mechanism of these compounds with the steel surface. Furthermore, molecular dynamic (MD) and Monte Carlo (MC) simulations show that NDPP is a more effective inhibitor than DDPP, as it combines good adsorption with more efficient surface coverage and better interactions with metal and water.

Keywords: Eco-friendly synthesis; Inhibitors; Corrosion; Carbon steel; Electrochemical techniques; DFT; MD

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-026-04875-6

Chemical Papers 80 (7) 8081–8098 (2026)