Porous Phosphorescent Coordination Polymers for Oxygen Sensing

摘要

Coordination polymers represent a new class of tunable materialsnthat have shown great promise in a number of applications,nincluding gas storage,n1ncatalysis,n2nnonlinear optics,n3nand nanomedi-ncine.n4nBecause of their propensity to exhibit high porosity,ncoordination polymers provide an interesting platform for probingnthe interactions between the frameworks and gaseous molecules.nA large number of luminescent coordination polymers havenappeared in the literature over the past decade,n5neither by takingnadvantage of the intrinsic fluorescent property of the organicnbridging ligands or the luminescent property of a lanthanide metalnion (such as Eu3nor Tb3n).n6nThe luminescent properties of porousncoordination polymers can be perturbed by a small molecule ornion, thereby providing an effective means for chemical sensing.nRecently, a microporous fluorescent coordination polymer wasnshown to reversibly detect high explosives in the gas phase,n7nwhereas lanthanide-based luminescent coordination polymers werenshown to respond to the presence of a metal ion or an anion innsolution.n8nCyclometalated Ir complexes such as Ir(ppy)3 (where ppynis 2-phenylpyridine) are highly efficient phosphorescent moleculesnowing to the facile intersystem crossing to populate the 3nMLCTnstates, and have been extensively used in light-emitting devices.n9nThe 3nMLCT phosphorescence can be readily quenched by moleculesnwith a triplet ground state, thereby providing accurate sensing fornoxygen.n10nWe hypothesized that Ir(ppy)3 derivatives can benincorporated into coordination polymers to lead to highly phos-nphorescent materials as chemical sensors. Herein we report thendesign and synthesis of highly phosphorescent coordination poly-nmers based on Ir(ppy)3 derivatives and their application in oxygennsensing via luminescence quenching.