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The corrosion inhibition power of an eco-friendly green inhibitor Ixora coccinea extract (ICE) for mild steel in 1 M HCl and 0.5 M H2SO4 was analysed using physicochemical and electrochemical techniques. 1–5 v/v% ICE was prepared and added into the corrosive acidic media for different analyses. Weight loss measurements conducted for a period of 24hrs for mild steel immersion revealed 89.38% and 77.96% inhibition capacity of ICE in 1 M HCl and 0.5 M H2SO4 medium respectively. Electrochemical impedance parameters show that as concentration is increased, efficiency increases and double layer capacitance decreases. Potentiodynamic polarization techniques are also in good agreement with impedance studies and exhibit the mixed type inhibition character of ICE. Electrochemical noise spectrum also strongly supports the anti-corrosive property of ICE and the magnitude of noise signal decreases concerning the increase in ICE concentration. Ixorene, which is one of the major constituents of Ixora coccinea leaves was also studied for its corrosion inhibition nature by quantum mechanical calculations and was found to match with all other results. Adsorption studies of ICE are in accordance with Langmuir isotherm. Surface morphological studies confirm the formation of a protective barrier on mild steel surface in both media, i.e., 1 M HCl and 0.5 M H2SO4.

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Novel thiadiazole derivatives of Schiff bases namely (E)-N-(anthracen-9-ylmethylene)-5-(4-nitrophenyl)-1,3,4-thiadiazol-2-amine (A9CNPTDA) and N-(anthracen-9(10H)-ylidene)-5-(4-nitrophenyl)-1,3,4-thiadiazol-2-amine (ANNPTDA) were synthesized, characterized and corrosion inhibition behaviour, as well as the mechanism of inhibition were investigated by different monitoring techniques like gravimetric measurements, electrochemical impedance spectroscopy, potentiodynamic polarization, quantum chemical and SEM studies. Both of the thiadiazole derivatives showed excellent corrosion inhibitor action on carbon Steel in acid medium. A9CNPTDA exhibited highest inhibition efficiency of 98.04% at 1mM concentration while ANNPTDA showed a maximum of 95.32%. In HCl medium, both derivatives obeyed Langmuir adsorption isotherm and thermodynamic parameters (Kads, ΔG0ads) were calculated. An acceptable relationship was observed between the results of quantum chemical calculations and other corrosion monitoring analysis.

Background Schiff base compounds have extensive applications in various fields such as analytical, inorganic, organic, and biological fields. They have excellent pharmacology application prospects in the modern era and are widely used in the pharmaceutical industry. In the present work in vitro antibacterial and in silico docking studies of two Schiff base compounds 2,2’-(5,5-dimethylcyclohexane-1,3-diylidene)bis(azan-1-yl-1-ylidene)diphenol (DmChDp) and N,N’-(5,5-dimethylcyclohexane-1,3-diylidene)dianiline (DmChDa) were carried out against the bacterial strain Staphylococcus aureus and its target proteins. Results The tests proved that the ligands have potential antibacterial activity. In the computational analysis, the drug-like properties of the compounds were first pre-filtered using the Lipinski rule of five. Then, molecular docking study was conducted using the AutoDock 4.2 program, to establish the mechanism by which the molecules inhibit the growth of S. aureus. For this purpose, 6 different target proteins (PDB ID: 1T2P, 3U2D, 2W9S, 1N67, 2ZCO, and 4H8E) of S. aureus were selected. Both the Schiff bases showed a good binding affinity with the target protein dihydrofolate reductase enzyme (PDB ID: 2W9S) but in different sites. Maximum binding energies of about − 10.3 and − 10.2 kcal/mol were observed when DmChDp and DmChDa were docked with 2W9S. Conclusion Schiff base compounds DmChDp and DmChDa have appreciable growth-inhibitory power against S. aureus, which can be attributed to the deactivation of the enzyme, dihydrofolate reductase.