Robust Lanthanoid Picolinate-Based Coordination Polymers for Luminescence and Sensing Applications

Area of Science:

• Materials Chemistry
• Coordination Chemistry
• Luminescent Materials

Background:

• Picolinate-based ligands are valuable building blocks for metal-organic frameworks.
• Europium(III) complexes are known for their luminescent properties, useful in sensing.
• Developing robust and selective sensors for nitroaromatics and metal ions is crucial.

Purpose of the Study:

• To synthesize and characterize novel europium(III) coordination polymers using picolinate-based ligands.
• To investigate the luminescent properties and sensing capabilities of these polymers for nitroaromatic compounds and Fe3+ ions.
• To evaluate the structural robustness and stability of the synthesized materials.

Main Methods:

• Synthesis of picolinate-based dianionic ligands (L1 and L2).
• Hydrothermal synthesis of europium(III) coordination polymers 1 and 2.
• Luminescence spectroscopy, including Stern-Volmer quenching studies for nitrobenzene and Fe3+.
• Structural characterization and stability testing across a wide pH range.

Main Results:

• Two novel, robust, and luminescent europium(III) coordination polymers, [Eu(H2O)2(L1)2]- and [Eu(L2)2]-, were synthesized.
• Both polymers exhibited high selectivity and sensitivity for detecting nitroaromatic compounds (nitrobenzene) and Fe3+ ions via luminescence quenching.
• Stern-Volmer constants (KSV) for nitrobenzene were 150 M-1 and 160 M-1, and for Fe3+ were 471 M-1 and 706 M-1 for polymers 1 and 2, respectively.
• The coordination polymers demonstrated stable emissive properties over a broad pH range, indicating structural robustness.

Conclusions:

• The synthesized picolinate-based europium(III) coordination polymers are effective luminescent sensors.
• These materials show significant potential for selective and robust detection of nitroaromatic compounds and Fe3+ ions.
• The stability of their emissive properties across varying pH conditions highlights their practical applicability in sensing devices.