In this research two new Schiff bases N,N'-bis[(3,4-dihydroxy-5-nitrophenyl)methylidene]thiourea (BDHNPMTU)                and 2-[(3,4-dihydroxy-5-nitrophenyl)methylidene]hydrazine-1-carbothioamide (DHNPMHC) were synthesized by condensation of 3,4-dihydroxcy-5-nitro-benzaldehyde with Thiourea and Thiosemicarbazide. The structures of Schiff bases were fully characterized by elemental analysis, FT-IR and UV–Vis methods. The inhibitive effects of two Schiff bases BDHNPMTU and DHNPMHC towards the corrosion on copper in 0.5M HCl were investigated using weight loss measurement technique. Surface morphology of metal surface in presence and absence of inhibitors were studied by scanning electron microscope (SEM). Results show that both BDHNPMTU and DHNPMHC are an effective inhibitor for copper corrosion in 0.5 M HCl solution. It was found that inhibition efficiency increases with increasing concentration of inhibitor. Adsorption of the inhibitor on the copper surface followed Langmuir adsorption isotherm. SEM study also support the inhibition of corrosion of copper. BDHNPMTU and DHNPMHC show maximum inhibition efficiency i.e. 96% and 95.83% at highest concentration of inhibitor (5X10-5M). The order of inhibition efficiency of the two Schiff’s bases for Cu metal are BDHNPMTU>DHNPMHC.

In this research study Schiff base (E)-N-(5bromopyridin-2-yl)-1-(4-ethylphenyl) methanimine (BPEPM) synthesized by condensation of 4-ethyl benzaldehyde and 2amino-5-bromopyridine. The Schiff base was characterized by elemental analysis, IR and NMR spectroscopic methods. The corrosion inhibition effect of Schiff base BPEPM on the corrosion of iron in 0.5M HCl was studied by using mass loss method. The mass loss parameter like corrosion rate, inhibition efficiency and surface coverage show that Schiff base BPEPM is an efficient inhibitor for iron corrosion in 0.5M HCl solution. The surface coverage and inhibition efficiency increase with concentration of Schiff base BPEPM increases. In corrosive medium inhibitor instantaneously forms a protecting layer on iron surface and retards the corrosion reaction. The plot log (𝜽/1-𝜽) versus logC (mol/L) show linearity it means adsorption of inhibitor obey Langmuir adsorption isotherm pattern. The inhibition efficiency of inhibitor increases with time duration. In 72-hour time duration Maximum inhibition efficiency (95.7%) is shown towards iron corrosion at highest concentration of inhibitor (5X10 -5 M).