Breathing-Dependent Redox Activity in a Tetrathiafulvalene-Based Metal-Organic Framework.

"Breathing" metal-organic frameworks (MOFs) that involve changes in their structural and physical properties upon an external stimulus are an interesting class of crystalline materials due to their range of potential applications including chemical sensors. The addition of redox activity opens up a new pathway for multifunctional "breathing" frameworks. Herein, we report the continuous breathing behavior of a tetrathiafulvalene (TTF)-based MOF, namely MUV-2, showing a reversible swelling (up to ca. 40% of the volume cell) upon solvent adsorption. Importantly, the planarity of the TTF linkers is influenced by the breathing behavior of the MOF, directly impacting on its electrochemical properties and thus opening the way for the development of new electrochemical sensors. Quantum chemical calculations and Raman spectroscopy have been used to provide insights into the tunability of the oxidation potential.