¹O₂ Generating Luminescent Lanthanide Complexes with 1,8-Naphthalimide-Based Sensitizers

Area of Science:

• Coordination Chemistry
• Photophysics
• Materials Science

Background:

• Lanthanide complexes are explored for their unique luminescent and photophysical properties.
• 1,8-naphthalimide derivatives are known for their versatile applications in sensing and imaging.

Purpose of the Study:

• To synthesize and characterize novel lanthanide complexes using 1,8-naphthalimide-based ligands.
• To investigate the photophysical properties, including luminescence sensitization and singlet oxygen generation, of these new complexes.

Main Methods:

• Synthesis of two new 1,8-naphthalimide-based ligands: Nap-dpe and Nap-cbx.
• Formation and isolation of lanthanide ion (Ln^III) complexes with these ligands.
• Photophysical characterization including luminescence quantum yield measurements and singlet oxygen generation efficiency determination.

Main Results:

• The ligands Nap-dpe and Nap-cbx successfully sensitize visible and near-infrared emitting Ln^III ions (Eu^III, Nd^III, Yb^III).
• High singlet oxygen (¹O₂) generation efficiencies were observed, reaching up to 64% for [Ln(Nap-cbx)₃]³⁺ complexes.
• Eu^III luminescence quantum yields were measured at 16.7% for [Eu(Nap-cbx)₃]³⁺ and 8.3% for [Eu(Nap-dpe)₃]³⁺, increasing in oxygen-free environments.

Conclusions:

• The developed 1,8-naphthalimide-based ligands form efficient lanthanide sensitizers and singlet oxygen generators.
• These complexes hold potential for applications in photodynamic therapy and luminescent materials.
• The photophysical properties can be tuned by ligand choice and the lanthanide ion.