Theoretical studies on the corrosion inhibition characteristics of thiosemicarbazide derivatives

Quantum chemical calculations using B3LYP and RHF methods with the 6-311G(d,p)  and 6-311++G(2d,2p) basic sets and CBS-Q method were used and performed to give further insight into the inhibition mechanism of benzaldehyde thiosemicarbazone (BTSC), p-chlorobenzaldehyde thiosemicarbazide (PCIBTSC), 4-dimethylaminobenzaldehyde thiosemicarbazide (4DMBTSC) for neutral and pronated forms in gas phase and water phase. These include, energy of the highest occupied molecular orbital energy (EHOMO), the lowest unoccupied molecular orbital energy (ELUMO), the energy gap between ELUMO and EHOMO (?E), chemical hardness (h), softness (s), electronegativity (c), chemical potential (m), global electrophilicity (?), nucleofugality (DEn) and electrofugality (DEe) were found correlation coefficient between the experimental inhibition efficiency (IE %) and theoretical results.</p