Circularly polarized luminescence from Tb(III) interacting with chiral polyether macrocycles

Area of Science:

• Supramolecular Chemistry
• Coordination Chemistry
• Chiroptical Spectroscopy

Background:

• Chiral macrocycles are crucial in molecular recognition and sensing.
• Terbium complexes are known for their luminescence properties.
• Developing new ligands for lanthanide ions is an active research area.

Purpose of the Study:

• To synthesize novel chiral amide-based bis-pyridine polyether macrocycles.
• To investigate the complexation of these ligands with terbium(III) ions.
• To study the chiroptical properties of the resulting complexes.

Main Methods:

• Two-step synthesis of chiral macrocycles.
• Complexation studies with terbium(III) ions.
• Spectroscopic analysis including Electronic Circular Dichroism (ECD) and Circularly Polarized Luminescence (CPL).
• Structural elucidation via NMR, spectrophotometric titration, and solid-state analysis.

Main Results:

• A series of chiral amide-based bis-pyridine polyether macrocycles were successfully synthesized.
• One ligand demonstrated spontaneous complexation with terbium(III) ions.
• Significant changes in chiroptical properties were observed upon complexation, including ECD sign inversion and enhanced luminescence.
• A terbium-centered CPL signal with a luminescence dissymmetry factor (g_lum) of 0.05 was detected.

Conclusions:

• The synthesized chiral macrocycles are effective ligands for terbium(III).
• Terbium complexation induces notable chiroptical responses, useful for sensing and optical materials.
• The study provides insights into the coordination chemistry and structural aspects of these chiral lanthanide complexes.