Reversible in situ Control over Monolayer Organization

Cr²⁺ and Cr³⁺ ions are shown to mediate the formation, morphology, and organization of arachidic acid (AA) Langmuir-Blodgett (LB) monolayers. This finding, based on cyclic voltammetry (CV), linear sweep voltammetry (LSV) and fluorescence recovery after photobleaching (FRAP) measurements, show that Langmuir monolayer formation depends on subphase pH and metal ion concentration. Following monolayer deposition on indium tin oxide (ITO), the LB monolayer organization can be modified reversibly through control of the Cr oxidation state, which has not been shown before by other monolayers formed with other divalent metal ions. The dynamics and the mobility of a chromophore (perylene) incorporated into the monolayer sense changes in Cr oxidation state-dependent organization of the LB monolayer. Demonstrating reversible changes in monolayer organization provides an opportunity to control chemical and electron access to the interface support.