Energy-efficient synthesis along with in-depth insight into anticorrosion behavior of double-armed phenylenebis(azanylylidene)bis(methanylylidene) derivatives: A symphony of green defense unveiling the 4E synergy

Abstract

In alignment with the principles of green chemistry as well as environmental sustainability, herein two novel double-armed corrosion inhibitors (CIs) namely, 5,5′-((1,4-phenylenebis(azanylylidene))bis(methanylylidene))bis(2-methoxyphenol) (PAMM-1) and 6,6′-((1E,1′E)-(1,4-phenylenebis(azanylylidene))bis(methanylylidene))bis(2-methoxyphenol) (PAMM-2) were synthesized through energy-efficient ultrasound assisted synthetic pathway. Both of the CIs exhibited excellent corrosion inhibition properties toward the protection of mild steel (MS) in static HCl medium. Remarkably, the highest inhibition efficiency (IE) achieved through electrochemical analysis was 94.7% and 93.4% for 4 mM of PAMM-1 and PAMM-2, respectively. Morphological analysis has been evaluated through field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and water contact angle (WCA) measurements. The protective performance of CIs have been validated using density functional theory (DFT) and non covalent interaction (NCI) in a perceptive way. To delve deeper into the molecular level insights, the interactions of the CIs with corrosive elements and metal atoms in a real corrosive environment have been analyzed using molecular modelling, indicating spontaneous adsorption of the green CIs with high binding energy (947.37 kJ/mol). The present research is shedding light on how the IE is influenced by different positional substituents (–OCH3 and –OH) within the molecular scaffold, resulting in the ultimate achievement of ‘4E factors’: energy, economy, environment, and efficiency.