Luminescent Lanthanide Complex Sensor for Acac and Cd²

Area of Science:

• Coordination Chemistry
• Materials Science
• Analytical Chemistry

Background:

• Lanthanide coordination complexes offer unique luminescent properties.
• Development of selective sensors for analytes like acetylacetonate (acac) and cadmium ions (Cd2+) is crucial.
• Phenylmalonic acid and phenanthroline are effective ligands for constructing lanthanide complexes.

Purpose of the Study:

• To synthesize novel lanthanide coordination complexes using phenylmalonic acid and phenanthroline.
• To investigate the stability of these complexes in aqueous solutions across a range of pH values.
• To evaluate the potential of the synthesized terbium (Tb) complex as a bifunctional sensor for acac and Cd2+.

Main Methods:

• Synthesis of lanthanide coordination complexes [Ln2(PAA)4(phen)2(NO3)2] from Ln(NO3)3·6H2O, phenylmalonic acid (H2pmal), and 1,10-phenanthroline (phen).
• Stability testing of the complexes in neutral, acidic (pH 4), and basic (pH 10) aqueous solutions.
• Luminescence spectroscopy was employed to assess the sensing capabilities of the Tb complex.

Main Results:

• Two stable lanthanide complexes, [Ln2(PAA)4(phen)2(NO3)2] (Ln = Tb, Eu), were successfully synthesized.
• The complexes demonstrated excellent stability in aqueous solutions across a wide pH range (pH 4-10).
• The Tb complex exhibited bifunctional sensing behavior: luminescence 'turn on' for acac and 'turn off' for Cd2+, with limits of detection of 90 nm and 0.5 μm, respectively.

Conclusions:

• Novel, stable lanthanide coordination complexes have been developed.
• The Tb complex serves as an effective bifunctional sensor for acac and Cd2+ with high sensitivity.
• The detailed sensing mechanisms provide insights for designing advanced luminescent probes.