Metal organic frameworks (MOFs) are extended coordination materials consisting of nodal metal sites, which can be either single ions or small clusters of ions, interconnected by multidentate organic ligands. By virtue of the molecular shapes of the linker groups, a range of framework topologies ensue, all the way up to fully 3-dimensional extended systems that can include large internal voids or pores. This relatively new breed of materials potentially have widespread applications including catalysis, sequestration, separation technologies, molecular recognition and even medical applications.
We are currently working on metal organic frameworks (MOFs) based on rare earth elements and organic linkers. By varying the reaction conditions, we have perfected the synthesis of MOFs that have either single Eu ions or hexanuclear Eu clusters at the nodal points, linked with a family of organic linkers. Research is currently focused on families of Eu MOFs that are isostructural with the well-known Zr-based UiO-66 family. These are of particular interest given the biological inertness of Eu, coupled to its strong fluorescence, distinguishing them from the Zr systems, whilst the cubic structures lead to large internal voids. One aim of this research is to use such MOFs in biological applications such as drug delivery - for this purpose additional functionalisation of the linkers is required to tailor the MOF properties.