Combined Quantum Mechanical and Electrochemical Study of New Isatin Derivative as Corrosion Inhibitor for Carbon Steel in 3.5 % NaCl

The inhibiting efficiency of synthesis a new derivative of 5-bromo isatin it is N- [ (hexahydrodiazepine -3, 7-dione-1-yl) aceto]-3- (tolylimino) -5-bromo-2-oxo-indole] (5BID) towards carbon steel corrosion have been investigated in three media (vacuum, DMSO, and H2O) using PM3 and DFT quantum mechanical calculations of (B3LYP) with a 6-311++G (2d, 2p) by using Gaussian-09 program. The calculated physical properties and quantum chemical parameters correlated to the inhibition efficiency all are studied and discussed at the equilibrium geometry in the three media, the result show that the studied derivativ could be absorbed on carbon steel surface with very good inhibition efficiency by offering electrons from the rich hetero-atoms nitrogen, oxygen, sulfur, and electrons of isatin ring to the unoccupied d-orbitals of Fe metal forming anti-bonding orbital-feedback bonds and also experimental studies of carbon steel corrosion inhibition in 3.5 % NaCl solution by (5BID) was account using potentiodynamic polarization, SEM (Scanning Electron Microscopy) and AFM (Atomic Force Microscopy) and EDS (Energy Dispersive Spectroscopy) measurements