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Ultrabright oxygen optodes based on cyclometalated iridium(III) coumarin complexes
Sergey M Borisov1, Ingo Klimant
1Institute of Analytical Chemistry and Radiochemistry, University of Technology Graz, Stremayrgasse 16, 8010 Graz, Austria. sergey.borisoz@tugraz.at
Analytical Chemistry
|August 28, 2007
Summary
New iridium(III) coumarin complexes offer brighter, more sensitive optical oxygen sensing. These probes show potential for monitoring fast processes and in nanoparticles, despite lower photostability.
Area of Science:
- Materials Science
- Analytical Chemistry
- Photochemistry
Background:
- Optical oxygen sensors are crucial for various applications.
- Existing probes like ruthenium(II) polypyridyl dyes and porphyrin complexes have limitations in brightness and sensitivity.
- There is a need for novel probes with improved optical properties and fine-tunable sensitivity.
Purpose of the Study:
- To develop and characterize novel cyclometalated iridium(III) coumarin complexes for optical oxygen sensing.
- To compare their performance against established oxygen sensing probes.
- To evaluate their potential applications in different formats like thin films and nanoparticles.
Main Methods:
- Synthesis and characterization of cyclometalated iridium(III) coumarin complexes.
- Spectroscopic analysis (absorption, emission, quantum yield).
- Luminescence lifetime measurements and oxygen sensitivity studies in polystyrene films.
- Assessment of temperature cross-sensitivity and photostability.
Main Results:
- Iridium(III) coumarin complexes exhibit superior visible absorption and higher quantum yields compared to ruthenium(II) and porphyrin probes, leading to higher brightness.
- Spectral properties and oxygen sensitivity are tunable via coumarin ligand modification and complex structure (monomeric/dimeric).
- Probes demonstrate optimal luminescence decay dynamics for oxygen monitoring across 0-100% air saturation with lower temperature cross-sensitivity than ruthenium probes, but possess lower photostability.
Conclusions:
- Cyclometalated iridium(III) coumarin complexes are promising candidates for optical oxygen sensing, offering high brightness and tunable sensitivity.
- Their suitability for applications requiring high sensitivity and fast response times, such as thin films and nanoparticles, is highlighted.
- While photostability is a limitation for long-term use, these probes provide reliable oxygen monitoring with reduced errors, especially when temperature compensation is not applied.
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