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Ab- initio quantum chemical study of semicarbazide and 4-phenylsemicarbazide on mild steel surface as two anti corrosion inhibitors

AzitaKhosravan, Mahdeyeh Sheikhshoaie, Iran Sheikhshoaie

Quantumchemicalmethods are becoming evermore prevalent for assessing surface interactions semicarbazid(SC) and 4-phenylsemicarbazide (4- PSC).Thequantumchemicalcalculationshavebeenperformed byusingDFT, ab-initiomolecular orbital and semi-empiricalmethods for SCand 4-PSCbeing corrosion inhibitors and its comparisonwith that available experimental data. Interaction energies of these compounds on the surface or iron are calculated in hydrochloric acidmediumbyusingquantumchemical calculationsatDFTlevel. Allcalculationshavebeenperformed usingtheGaussian03Wsuite of programs. Itwas found that theoretical data support experimental results.The highestoccupiedmolecularorbital energy(EHOMO), low-est unoccupiedmolecular orbital energy (ELUMO), the energy gap between EHOMO and ELUMO (ÄEHOMO–LUMO), dipolemoments (ì), charges on theOandNatoms, the total energies of themolecules.The results of quantum chemicalcalculationsandexperimentalefficienciesof inhibitorswere subjected to correlation analysis.We have reached the conclusion that the synthesis of better corrosion inhibitors can be achieved bycontrollingall electronic properties and parameters of a selected group of molecules