Electrochemistry in nanostructured inorganic molecular materials

We have previously described the synthesis of a family of molecular 'squares' based on octahedral Re(I) coordination of difunctional bridging ligands. The size and chemical composition of the square cavity is highly tunable, and the inorganic cyclophanes are being actively studied in catalytic, separations, and sensing applications. Electrochemical techniques have been primary methods for characterization of the transport properties of thin films of the nanostructured materials. For example, cyclic voltammetry and rotating disk electrode voltammetry experiments have revealed size-selective permeation by redox probes, where the size cutoff is determined by the internal square dimensions. We have more recently begun to employ scanning electrochemical microscopy to spatially image micropatterned electrodes containing these thin film materials, simultaneously allowing us to obtain permeability data and topographical information. This paper describes data obtained by employing porphyrin-based molecular squares that feature chemically tailored cavities.