In the realm of advanced chemical development, computational chemistry plays an increasingly vital role in predicting and understanding the performance of new materials. At NINGBO INNO PHARMCHEM CO.,LTD., we leverage these powerful tools to enhance our product development process, particularly in the field of corrosion inhibition. Our studies on Cinnamaldehyde Thiosemicarbazone (CT) as a protector for mild steel in acidic media have extensively utilized Density Functional Theory (DFT) to gain deep molecular insights.

DFT calculations allow us to investigate the electronic structure of molecules and predict their behavior and reactivity. For corrosion inhibitors, understanding the distribution of electrons and the energy levels of frontier molecular orbitals (HOMO and LUMO) is critical. These properties directly correlate with a molecule's ability to adsorb onto a metal surface and form a protective layer.

Our DFT analysis of CT and its precursors revealed significant findings. The Highest Occupied Molecular Orbital (HOMO) represents the outermost electrons of a molecule, indicating its potential to donate electrons. A higher HOMO energy level generally suggests a greater tendency for electron donation, which is crucial for forming chemisorptive bonds with metal surfaces. CT exhibited higher HOMO energy values compared to its individual components, indicating enhanced electron-donating capabilities. This suggests that CT is more prone to interacting with the vacant d-orbitals of iron atoms in mild steel, a key step in forming a strong protective film.

The Lowest Unoccupied Molecular Orbital (LUMO) represents the lowest energy state for accepting electrons. The energy gap between HOMO and LUMO (( Delta E )) is also a crucial indicator of molecular stability and reactivity. A smaller ( Delta E ) generally correlates with greater electron delocalization and a stronger tendency for adsorption. Our calculations showed that CT possesses a smaller HOMO-LUMO energy gap compared to its precursors, further supporting its robust adsorption and superior corrosion inhibition performance.

Furthermore, Mulliken charge distribution analysis provided insights into the specific atoms within the CT molecule that are most likely to interact with the metal surface. Regions with higher negative charges, particularly on heteroatoms like nitrogen and sulfur, indicate potential adsorption sites. The presence of these electron-rich centers in CT enhances its affinity for the metal surface, contributing to the formation of a stable protective barrier.

By integrating these computational findings with our experimental results from techniques like EIS and PDP, we gain a comprehensive understanding of CT's mechanism of action. This synergy between theoretical prediction and experimental validation is fundamental to our approach at NINGBO INNO PHARMCHEM CO.,LTD. It allows us to develop highly effective and reliable chemical solutions, such as Cinnamaldehyde Thiosemicarbazone, that address critical industrial needs like corrosion control in challenging acidic environments.