Bimetallic cyclometalated iridium complexes bridged by a BODIPY linker

et al. 2022

Chem. Sci.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Cyclometalated iridium-coumarin ratiometric oxygen sensors: improved signal resolution and tunable dynamic ranges

et al. 2022

Chem. Sci.

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“…This same synthetic strategy has been used in our group to access other multi-component photoactive structures, which are not ratiometric sensors but nonetheless are valuable platforms for studying excited-state energy transfer pathways. 34,35 Some of the Ir-BODIPY compounds prepared in this way functioned as effective ratiometric oxygen sensors, with dynamic ranges that spanned hypoxic levels of O2 (pO2 ≤ 150 mmHg). 33 In this work, we present two significant advances in the design of ratiometric oxygen sensors featuring cyclometalated iridium, showing that the simple synthetic approach we have developed facilitates modification and optimization of the sensor attributes.…”

Section: Introductionmentioning

confidence: 99%

Cyclometalated Iridium-Coumarin Ratiometric Oxygen Sensors: Improved Signal Resolution and Tunable Dynamic Ranges

et al. 2022

Preprint

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In this work we introduce a new series of ratiometric oxygen sensors for hypoxic environments based on phosphorescent cyclometalated iridium centers partnered with organic coumarin fluorophores. Three different cyclometalating ligands and two different pyridyl-containing coumarin types were used to prepare six target complexes with tunable excited-state energies. Three of the complexes display dual emission, with fluorescence arising from the coumarin ligand, and phosphorescence from either the cyclometalated iridium center or the coumarin. These dual-emitting complexes function as ratiometric oxygen sensors, with the phosphorescence is quenched under O₂ while fluorescence is unaffected. The use of blue-fluorescent coumarins results in good signal resolution between fluorescence and phosphorescenc. Moreover, the sensitivity and dynamic range, measured with Stern-Volmer analysis, can be tuned two orders of magnitude by virtue of our ability to synthetically control the triplet excited-state ordering. The complex with cyclometalated irdium 3MLCT phosphorescence operates under hyperoxic conditions, whereas the two complexes with coumarin-centered phosphorescence are sensitive to very low levels of O¬2 and function as hypoxic sensors.

“…This same synthetic strategy has been used in our group to access other multi-component photoactive structures, which are not ratiometric sensors but nonetheless are valuable platforms for studying excited-state energy transfer pathways. 32,33 Some of the Ir-BODIPY compounds prepared in this way functioned as effective ratiometric oxygen sensors, with dynamic ranges that spanned hypoxic levels of O2 (pO2 ≤ 150 mmHg). 31 In this work, we present two significant advances in the design of ratiometric oxygen sensors featuring cyclometalated iridium, showing that the simple synthetic approach we have developed facilitates modification and optimization of the sensor attributes.…”

Section: Introductionmentioning

confidence: 99%

Cyclometalated Iridium-Coumarin Ratiometric Oxygen Sensors: Improved Signal Resolution and Tunable Dynamic Ranges

et al. 2021

Preprint

Self Cite

In this work we introduce a new series of ratiometric oxygen sensors for hypoxic environments based on phosphorescent cyclometalated iridium centers partnered with organic coumarin fluorophores. Three different cyclometalating ligands and two different pyridyl-containing coumarin types were used to prepare six target complexes with tunable excited-state energies. Some of the complexes exhibit only phosphorescence originating from the cyclometalated Ir moiety, as a result of excited-state energy transfer from the coumarin to the Ir-centered excited states. Three of the complexes display dual emission, with fluorescence arising from the coumarin ligands and phosphorescence from the cyclometalated iridium synthons, and hence function as ratiometric oxygen sensors. Oxygen quenching experiments with these complexes demonstrate that the iridium centered phosphorescence is quenched under O₂ while fluorescence is unaffected. These sensors have good signal resolution, and the sensitivity and dynamic range, measured with Stern-Volmer analysis, span two orders of magnitude. This work demonstrates that this simple, modular approach for conjoining fluorescent and phosphorescent molecules can produce effective oxygen sensors with a wide range of attributes.