Quantum Chemical and Monte Carlo Simulation Studies on Inhibition Performance of Caffeine and Its Derivatives against Corrosion of Copper

Abstract

Performance tests on caffeine’s corrosion inhibition properties and their derivatives against copper corrosion have been previously reported experimentally using gravimetric and electrochemical analyses. The test was able to measure the efficiency of their corrosion inhibition accurately. However, the caffeine and its derivatives’ structure patterns and coating mechanisms when interacting with metals during copper corrosion inhibition have not been explained in detail by experimental studies. In the present study, the theoretical density functional study (DFT), ab initio MP2, and Monte Carlo simulation approaches explain the problem. The geometrical and quantum chemical parameters of inhibitors were compared under normal and protonated conditions in the gas and aqueous environments. Theoretical studies can accurately determine the molecule’s geometrical parameters and successfully explain the quantum parameters of inhibitors. Molecular dynamics are applied to study the mechanism of interaction between inhibitors and metal surfaces in an explicit water molecule environment. The energy absorption of caffeine and its derivatives on metal surfaces was linear, with quantum parameters calculated from the density functional theory and an ab initio approach. Furthermore, these theoretical study results align with the previously reported experimental studies published by de Souza et al. The inhibition efficiency ranking of studied molecules preventing copper corrosion was caffeine > theobromine > theophylline. This theoretical approach is expected to bridge the gap in designing effective corrosion inhibitors.

Electrochemical and DFT Study of NaNO2/NaNO3 Corrosion Inhibitor Blends for Rebar in Simulated Concrete Pore Solution

“…The ΔE value can be used to assess the relative reactivity of the inhibitor The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) surfaces are shown in Figure 11. The HOMO surfaces provide information on the sites of the molecule in which the most loosely bound electrons are likely to be donated to the metal, while the LUMO surfaces show the regions in which electrons from the metal are likely to be back-donated to the inhibitor [41,43]. For NO 2 − , the largest portion of the HOMO concentrated around the π-bonds of the oxygen bonding where resonance occurs.…”

Electrochemical Analysis of the Influence of Purines on Copper, Steel and Some Other Metals Corrosion

“…However, these results also had to be proved, by agreement, with the experimental findings. Besides, Hadisaputra et al [50] tried to explain the ability of caffeine and its derivatives (theophylline and theobromine) to protect copper from dissolution using theoretical density functional theory (DFT), and Monte Carlo simulation studies. The molecular structure of the used methylxanthines is illustrated in Figure 5.…”

Electrochemical and quantum mechanical investigation of various small molecule organic compounds as corrosion inhibitors in mild steel

“…The π-electrons of the pyridine ring are found to form donoracceptor interactions with the vacant d-orbital of the Fe atoms with the substituents orienting upwards towards the solution of H þ and Cl À ions. The fraction of electrons, ΔN quantifies the transfer of electrons from the molecule to the metal, where electrons go from the less electronegative to the more densely packed Fe surface (equation 10) [38,39]. Although the magnitude of electron transfer for pyridine and its derivatives exhibited to be the lowest, this suggests an energetically favorable process where electrons from the heterocyclic ring are transferred unto the Fe atoms.…”