Structural flexibility and vapochromic gas response in a silver(I)-based flexible MOF

Flexible metal–organic frameworks (FLX-MOFs) have attracted increasing attention because their reversible structural transformations can induce unique adsorption and sensing properties. In this seminar, I will present our recent study on a silver(I)-based flexible MOF, KDU-1 ([Ag(cadaf)]ₙ; cadaf = 9-(4-carboxyanilino)-4,5-diazafluoren), which exhibits gate-opening adsorption behavior and reversible vapochromic response toward guest molecules. Single-crystal X-ray diffraction analysis revealed an interdigitated two-dimensional framework containing one-dimensional channels. Gas adsorption measurements demonstrated selective gate-opening-type CO₂ adsorption, while in situ powder X-ray diffraction directly captured the structural transformation induced by gas uptake. In addition, reversible color changes associated with solvent adsorption/desorption indicate strong coupling between framework dynamics and optical properties. These results highlight the potential of flexible MOFs as multifunctional materials for gas sensing and responsive porous materials.