AUTHOR=Thornton Matthew E. , Hemsworth Jake , Hay Sam , Parkinson Patrick , Faulkner Stephen , Natrajan Louise S. 

TITLE=Heterometallic lanthanide complexes with site-specific binding that enable simultaneous visible and NIR-emission

JOURNAL=Frontiers in Chemistry

VOLUME=11

YEAR=2023

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2023.1232690

DOI=10.3389/fchem.2023.1232690

ISSN=2296-2646

ABSTRACT=<p>Macrocyclic lanthanide complexes have become widely developed due to their distinctive luminescence characteristics and wide range of applications in biological imaging. However, systems with sufficient brightness and metal selectivity can be difficult to produce on a molecular scale. Presented herein is the stepwise introduction of differing lanthanide ions in a bis-DO3A/DTPA scaffold to afford three trinuclear bimetallic [Ln<sub>2</sub>Ln’] lanthanide complexes with site-specific, controlled binding [(Yb<sub>2</sub>Tb), (Eu<sub>2</sub>Tb), (Yb<sub>2</sub>Eu)]. The complexes display simultaneous emission from all Ln<sup>III</sup> centers across the visible (Tb<sup>III</sup>, Eu<sup>III</sup>) and near infra-red (Yb<sup>III</sup>) spectrum when excited <italic>via</italic> phenyl ligand sensitization at a wide range of temperatures and are consequently of interest for exploiting imaging in the near infra-red II biological window. Analysis of lifetime data over a range of excitation regimes reveals intermetallic communication between Tb<sup>III</sup> and Eu<sup>III</sup> centers and further develops the understanding of multimetallic lanthanide complexes.</p>