Monolayer growth and exchange kinetics for alkylamines on the high-temperature superconductor YBa2Cu3O7-δ

Using redox-active alkylamine adsorbates, the authors have studied monolayer growth and adsorbate-adsorbate exchange kinetics on YBa2Cu3O7-δ. Herein the authors show that the formation kinetics for monolayers of FcC-(O)NH(CH2)4NH2[Fc=(η5-C5H4)Fe(η5-C5H5)] do not follow typical Langmuir adsorption isotherm behavior. Specifically, a parabolic tailing in the isotherms has been attributed to the diffusion of adsorbates through the porous material. The displacement of surface-adsorbed FcC(O)NH(CH2)4NH2 by another redox-active alkylamine, Fc(CH2)6NH2, has been studied and determined to be a reversible and dynamic process. Concentration dependence studies suggest that the exchange takes place via an associative process involving surface Cu(II) sites. The lability of the surface-adsorbed alkylamine ligands and the proposed exchange mechanism are consistent with the solution coordination chemistry of Cu(II)