Yb₂-Tb Upconversion in a Hetero-Trimetallic Molecular Lanthanide Complex

Area of Science:

• Materials Science
• Photochemistry
• Inorganic Chemistry

Background:

• Photon upconversion in lanthanide systems is limited by low chemical diversity.
• Developing molecular systems with tailored lanthanide ions is crucial for efficient upconversion.

Purpose of the Study:

• To investigate the multi-photon photophysical properties of novel hetero-trimetallic lanthanide complexes.
• To explore efficient photon upconversion via cooperative sensitization in Yb2Ln systems.
• To understand the influence of intermetallic distances and solvent quenching on energy transfer.

Main Methods:

• Synthesis of molecular hetero-trimetallic lanthanide complexes (Yb2Ln, where Ln = Eu3+, Gd3+, Tb3+).
• Spectroscopic analysis of photon upconversion properties in D2O and H2O.
• Computational studies using density functional theory (DFT) and molecular dynamics (MD) simulations to determine intermetallic distances.

Main Results:

• The Yb2Tb complex exhibited efficient Yb2 → Tb photon upconversion through cooperative sensitization in both heavy and light water.
• Yb2Eu did not display Yb2 → Eu upconversion, and Yb2Gd served as a spectroscopic control.
• Energy transfer in Yb2Tb was independent of OH quenching, and effective upconversion was observed despite long intermetallic distances (11.5-25 Å).

Conclusions:

• Kinetically inert building blocks enable site-specific control for introducing diverse lanthanide ions.
• Cooperative sensitization in Yb2Tb complexes facilitates efficient photon upconversion, even with significant intermetallic distances.
• The findings offer a pathway for designing advanced lanthanide-based upconversion materials with enhanced chemical diversity and robustness.