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Macrocyclic Eu3+ chelates show selective luminescence responses to anions
Christopher G Gulgas1, Theresa M Reineke
1Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221-0172, USA.
Inorganic Chemistry
|February 9, 2008
Summary
Lanthanide macrocycles show unique luminescence changes with specific anions like fluoride in DMSO. Anion binding to thiourea groups alters macrocycle shape, controlling the luminescent response for sensing applications.
Area of Science:
- Supramolecular Chemistry
- Luminescent Materials
- Anion Sensing
Background:
- Lanthanide-containing macrocycles offer potential for developing novel sensors.
- Thiourea moieties are effective in binding anions through hydrogen bonding.
- Tuning macrocycle structure influences binding pocket morphology and guest interactions.
Purpose of the Study:
- To design and synthesize lanthanide macrocycles with anion-responsive luminescence.
- To investigate the effect of anion basicity and macrocycle structure on luminescence.
- To elucidate the mechanism of anion interaction and its impact on luminescence.
Main Methods:
- Synthesis of lanthanide macrocycles (Eu2-Eu5) and model compounds.
- Luminescence spectroscopy (excitation, emission, lifetime) to monitor anion titrations.
- Absorbance and 1H NMR spectroscopy to study anion binding interactions.
Main Results:
- Macrocycles Eu2-Eu5 exhibited anion-dependent luminescence changes in DMSO.
- Luminescence intensity increased significantly with fluoride, acetate, and dihydrogen phosphate.
- Eu2 showed the largest luminescence enhancement (77%) with fluoride.
- Anion binding occurred at the thiourea groups, altering macrocycle conformation.
Conclusions:
- The synthesized macrocycles act as effective luminescent sensors for specific anions.
- Anion binding modulates the macrocycle's binding pocket, influencing luminescence.
- Structural variations in macrocycles fine-tune their anion recognition and signaling capabilities.
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