Metal-organic frameworks (MOFs) for sensing

MOFs, (the acronym for Metal-Organic Frameworks) are a quite new family of materials resulting from the combination of organic ligands and metal ions. The coordination between the metal centers and the organic scaffolds give rise to complex assemblies which can develop into coordination polymers from 1D to 3D structures. These materials are usually porous with well-defined channels or pores. For this reason, MOFs are able to absorb a number of molecules with very high efficiency. Depending on the combination of the metal and organic components, selectivity toward different classes of gases or organic molecules (guests) can be achieved. The interaction of the MOF with the guest often results in a modification of the MOF crystalline structure which eventually produce a change in the physical properties of the materials. These variations can be exploited to detect the presence of a specific guest. In this chapter, the application of MOFs for the sensing of chemical species will be briefly illustrated. After an introduction on of the structures and synthesis of MOFs, the different mode of sensing will be described. Then a number of examples from the recent literature will be discussed. The focus will be on two issues: the sensing of small molecules as gases, VOC and organic compounds, and the sensing of biomolecules. The former can find many uses in the industry, whereas the latter is a promising topic for biomedical applications.