Film quality and electronic properties of a surface-anchored metal-organic framework revealed by using a multi-technique approach

The virtually unlimited versatility and unparalleled level of control in the design of metal-organic frameworks (MOFs) has recently been shown to also entail a potential for applications based on the electrical and electronic properties of this rich class of materials. At present, methods to provide reliable and reproducible contacts to MOF materials are scarce; therefore, we have carried out a detailed, multi-technique investigation of an empty and loaded prototype MOF, HKUST-1. Epitaxial thin films of this material grown on a substrate by using liquid-phase epitaxy have been studied by cyclic voltammetry, atomic force microscopy, and quartz crystal microbalance and their quality assessed. By using an ionic liquid as the electrolyte, it is shown that redox-active molecules like ferrocene can be embedded in the pores, enabling a change in the overall conductivity of the framework and the study of the redox chemistry of guest molecules inside the MOF.