A versatile long-wavelength-absorbing scaffold for Eu-based responsive probes.

Area of Science:

• Coordination Chemistry
• Photophysics
• Luminescent Probes

Background:

• Europium(III) complexes are valuable luminescent materials.
• Coumarin derivatives can act as photosensitizers for lanthanide ions.
• Development of responsive luminescent probes is crucial for chemical sensing.

Purpose of the Study:

• Synthesize and characterize coumarin-sensitized, long-wavelength-absorbing Eu(III)-complexes.
• Investigate the effect of coumarin substituents on photophysical properties.
• Develop turn-on luminescent probes for reactive oxygen species detection.

Main Methods:

• Synthesis of Eu(III)-complexes featuring cyclen-based chelating frameworks linked to various coumarin derivatives.
• Characterization using spectroscopic techniques (UV/Vis absorption, luminescence).
• Evaluation of probe response to hydrogen peroxide and peroxynitrite.

Main Results:

• Successful synthesis of novel Eu(III)-coumarin complexes with tunable absorption and excitation spectra.
• Boronate-functionalized coumarin cages reacted with H(2)O(2) and peroxynitrite to yield 7-hydroxycoumarin species.
• Demonstrated a significant change in excitation profile upon cage cleavage, indicating a 'turn-on' response.
• Methoxybenzyl caged Eu-complex showed quenching by peroxynitrite in aqueous solution.

Conclusions:

• The 7-hydroxycoumarin antenna scaffold is effective for constructing turn-on and ratiometric luminescent probes.
• Coumarin photophysics modulation allows fine-tuning of lanthanide excitation properties.
• The developed probes show potential for sensitive detection of reactive oxygen species.