Oxygen sensing capabilities of a series luminescent zirconium-based porphyrinic metal–organic frameworks (MOFs) (PCN-222, PCN-223, and PCN-224) have been investigated. Design experiments allowed identification the most sensitive material, PCN-224 MOF. In this luminescence in air is quenched by up to 7.3-fold with bimolecular quenching constant kq 56,000 Pa–1 s–1, which significantly above previ...