Controlling Lanthanide Exchange in Triple-Stranded Helicates: A Way to Optimize Molecular Light-Upconversion

Area of Science:

• Coordination Chemistry
• Supramolecular Chemistry
• Materials Science

Background:

• Hexadentate gallium-based tripods exhibit tunable kinetic lability and inertness.
• Luminescent heterodimetallic helicates of the type [GaLn(L3)3]6+ can be formed via thermodynamic self-assembly.
• Lanthanide exchange studies reveal the structural stability of these helicates.

Purpose of the Study:

• To investigate the kinetic lability and inertness of gallium-based tripods in self-assembly.
• To explore the structural integrity of [GaLn(L3)3]6+ helicates under lanthanide exchange conditions.
• To utilize the stability of these complexes for doping and energy-transfer upconversion applications.

Main Methods:

• Thermodynamic self-assembly of heterodimetallic helicates.
• Lanthanide exchange experiments to assess structural stability.
• Spectroscopic analysis to monitor metal scrambling and energy transfer.
• Dilution of spectroscopically active ions into closed-shell matrices.

Main Results:

• Self-assembly of luminescent [GaLn(L3)3]6+ helicates occurs on the hour time scale.
• The triple-helical structure is preserved during lanthanide exchange.
• Connecting a second gallium tripod significantly slows down exchange processes.
• Spectroscopically active [CrErCr(L4)3]9+ can be diluted into [GaYGa(L4)3]9+ matrices without scrambling.

Conclusions:

• Gallium-based tripods offer a robust platform for constructing stable supramolecular architectures.
• The controlled assembly and inertness are crucial for creating doped materials.
• This approach facilitates molecular-based energy-transfer upconversion at room temperature.