Film quality and electronic properties of a surfaceanchored metal-organic framework as revealed by 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.VM acknowledges the EU for the funding through the granting of a Marie Curie Intra-European Fellowship (FP7-PEOPLE-2011; MOLSURMOF-301110). JL acknowledges the program of China Scholarship Council (CSC) for financial support. VM, JL and CW acknowledge A. Terfort for supplying the thiol derivatives. MP and CO acknowledge financial support from the Spanish Government through grants projects MAT2013-47869-C4-1-P and SEV-2015–0496, and Generalitat de Catalunya through grant project 2014 SGR 501.Peer reviewe