Thiophenyl Anilato-Based NIR-Emitting Lanthanide (Ln^III = Er, Yb) Dinuclear Complexes

Area of Science:

• Coordination Chemistry
• Photophysics
• Materials Science

Background:

• Lanthanide ions (Er^III, Yb^III) are known for their near-infrared (NIR) emission properties.
• Developing efficient optical antennas is crucial for sensitizing lanthanide luminescence.
• The photophysical properties of 3,6-dithiophene-anilate (Th₂An) ligand have not been previously investigated.

Purpose of the Study:

• To synthesize and characterize novel luminescent dinuclear lanthanide complexes.
• To investigate the photophysical properties of the Th₂An ligand.
• To explore the potential of Th₂An as an optical antenna for Er^III and Yb^III.

Main Methods:

• Synthesis of dinuclear complexes incorporating Er^III/Yb^III, Th₂An, and hydrotris(pyrazol-1-yl)borate ligands.
• Structural characterization using Single Crystal X-ray Diffraction (SC-XRD) and Powder X-ray Diffraction (PXRD).
• Comprehensive photophysical property investigation, including luminescence sensitization studies.

Main Results:

• Two novel dinuclear complexes, [((HB(pz)₃)₂Yb)₂(μ-th₂An)]·4DCM·1.3H₂O (1Yb) and [((HB(pz)₃)₂Er)₂(μ-th₂An)]·4DCM·1.8H₂O (1Er), were successfully synthesized and characterized.
• The Th₂An ligand demonstrated significant effectiveness as an optical antenna, efficiently sensitizing the NIR emission of both Er^III and Yb^III ions.
• Vibrational quenching was identified as a key factor impacting the efficiency of Ln^III NIR emission.

Conclusions:

• The Th₂An ligand is a highly effective optical antenna for sensitizing NIR-emitting Er^III and Yb^III ions in dinuclear complexes.
• Understanding and mitigating vibrational quenching is essential for optimizing NIR emission efficiency in lanthanide-based materials.
• These findings open avenues for designing advanced luminescent materials for applications requiring NIR emission.