Quantum Chemistry Study For Coordination Effect Of Crown Ethers And Corrosion Inhibition Effect Of Bipyrazole Derivatives

The structure-property of crown compounds and bipyrazolic-type compounds and the action mechanism of them with metal are studied by the quantum chemistry methods in this dissertation.First, a theoretical study of the cryptand [222] and the cryptand [222B] has been done using density functional theory (DFT) with B3LYP/6-31G* method in order to obtain the electronic and geometrical structure of the cryptands and their complexes with alkali metal ions: Li+, Na+ and K+. The nucleophilicity of cryptands have been analyzed through the Fukui function. For complexes, the match between cation and cavity size, the status of interaction between alkali metal ions and donor atoms in the cryptands and the rigidity of the cryptands have been analyzed through other calculated parameters. In addition, the enthalpies of complexation reaction and cation exchange reaction have been analyzed by the calculated thermodynamic data.Secondly, a theoretical study of four lariat crown ethers, including one aza-15-crown-5 lariat ether and two aza-18-crown-6 lariat ethers, has been done using density functional theory (DFT) with B3LYP/6-31G* method in order to obtain some parameters , such as E HOMO, E LUMO, and gap energy (ΔE ), etc. The coordination effect between lariat crown ether and lariat azacrown ether with alkali metal ions has been analyzed and compared according to the obtained parameters. At the same time, the importance of donor atoms pertaining to the side chain in the complexation reaction of three lariat azacrown ethers with alkali metal ions has been analyzed through the Fukui function.Finally, a theoretical study of five bipyrazolic-type organic compounds has been done using density functional theory (DFT) with B3LYP/6-31G* method in order to elucidate the different inhibition efficiencies and reactive sites of these compounds as corrosion inhibitors. The efficiencies of corrosion inhibitors and the global chemical reactivity relate to some parameters, such as E HOMO, E LUMO, gap energy (ΔE ) and other parameters, including electronegativity (χ), global hardness (η) and the fraction of electrons transferred from the inhibitor molecule to the metallic atom (ΔN ). The calculated results are in agreement with the experimental data on the whole. In addition, the local reactivity has been analyzed through the Fukui function and condensed softness indices.