ABSTRACT
Self-assembled monolayers are attractive for surface modification due to their ease of synthesis and the range of chemical functionality that can be applied. Metal-phosphonate monolayer properties can be controlled through the metal ions that can be used in their formation. The organization and fluid properties of these monolayers can be understood in the context of their thermodynamic properties and the association and dissociation kinetics that proceed at the metal-phosphonate complex. In this work, four different M(II)-phosphonate monolayers were synthesized and the diffusional behavior of free and tethered chromophores was evaluated using fluorescence recovery after photobleaching measurements. The ω-terminal group identity of the metal-phosphonate monolayer was varied to determine its effect on monolayer dynamics.
Subject(s)
Organophosphonates , Cations, Divalent , Diffusion , Photobleaching , Surface PropertiesABSTRACT
Self-assembled monolayers have been studied extensively due to their relative ease of synthesis and the broad range of applications for this class of materials. Monolayer-support interactions can range in strength from physisorption through covalent bond formation, with consequent variability in the robustness and fluidity of the monolayer. Monolayer-support bonding by metal ion complexation is especially attractive because of the ability to adjust the strength of interaction through metal ion identity. For such systems, both the exchange kinetics and thermodynamics of metal ion-complex formation contribute to the observed properties of the monolayer. We have synthesized metal-phosphate/phosphonate monolayers using Zr4+ and In3+ and have evaluated the metal ion dependence of monolayer dynamics for free and bound chromophores. Our findings reveal significant metal ion-dependent variations in monolayer dynamics and organization.
