Interaction of aqueous Cu(II) with carboxylic acid and alcohol terminated self assembled monolayers: Surface and interfacial characterization

Abstract

A detailed Polarization Modulation Infrared Reflection Absorption Spectroscopy (PM-IRRAS), X-Ray Photoelectron Spectroscopy (XPS) and electrochemical study of the interaction of copper(II) aqueous solutions with self-assembled monolayers of carboxylic acid and alcohol functionalized thiols of different lengths on gold is reported. Results show that all of these SAMs retain similar amounts of copper, that the interaction takes place mostly with the terminal functional groups, and that for short chain thiols, the copper is electrically connected to the electrode. Furthermore, upon interaction with the copper solution, most of the carboxylic acid moieties deprotonate, forming a complex with the copper cation. This information is relevant for the intelligent design of surfaces with affinity to metal cations that can be used as electrochemical sensors, or in systems for cleaning contaminated water.