Drinking and Breathing: Solvent Coordination-driven Plasticity of IRMOF-9

The coordination chemistry of Metal-Organic Frameworks is one key aspect when their applications and performances enhancement are pursued. This is usually investigated while cation exchanges or functionalisation reactions on open metal sites are involved. In this work we present a rare case of solvent coordination-induced breathing behaviour of a renowned Zn-based MOF, namely IRMOF-9, whose structural flexibility allows its framework topology to be retained upon dramatic coordination changes on their inorganic nodes. These are observed to accept from one to three additional coordination bonds from solvent molecules, depending on the coordination power of these latter and on temperature conditions. Structural studies by Single Crystal X-Ray Diffraction afforded precious insights on the occurring of such coordinative changes, suggesting that solvent molecules which dynamically bind the metal atoms are capable to play a decisive role in the final geometry of the framework.