Water Stability of Metal-Organic Framework HKUST-1

Metal-organic frameworks (MOFs) are a new class of crystalline porous materials, having wide pores which provide extremely high specific surface areas, larger than those typically observed in more common p orous materials like zeolites or activated carbons.This peculiar property combined with the frequent presence of open-metal sites, makes them very promising for a broad range of applications, spacing from gas storage or separation, drug delivery, toxic air removal, chemical detectors, etc.However, the industrialization of MOFs is still facing difficulties because of their low stability to water or even air moisture, a substance difficult to avoid in applications like those mentioned.Another issue concerning MOF industrialization consists in the low bulk density of the micrometric powder grains, which typically constitute such materials.Unfortunately, their low mechanical stability seems to make difficult even to enhance the packaging by simple mechanical compaction.In this review, we will particularly focus on the current state of art involving the MOF HKUST-1, especially on the degradation process involved when this MOF interacts with water molecules.Furthermore, we will show the connection between water and mechanical stability, bringing to attention of a study where solid tablets of HKUST-1 powder have been realized without any loss of crystallinity or porosity because of an accurate study on the effects of different degree of hydration during the tableting phases.In addition, in order to highlight the causes of damages induced in the framework upon interaction with water, a comparison with other two copper carboxylate MOFs will be shown, namely STAM-1 and STAM-17-OEt, which differ from HKUST-1 uniquely for the organic ligands.