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

Abstract

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 [Ln2Ln’] lanthanide complexes with site-specific, controlled binding [(Yb2Tb), (Eu2Tb), (Yb2Eu)]. The complexes display simultaneous emission from all LnIII centers across the visible (TbIII, EuIII) and near infra-red (YbIII) spectrum when excited via 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 TbIII and EuIII centers and further develops the understanding of multimetallic lanthanide complexes.

DMNP as an Effective Cage for Ln3+: A Spectroscopic and Thermodynamic Study

“…8−12 Furthermore, Ln 3+ complexes with nitrogen and oxygen binding sites have been studied for their enhanced emission properties that could be used for biological imaging. 13,14 As a poly(aminocarboxylate) entity, EDTA mainly forms a 1:1 complex with both divalent and trivalent metal cations through its four carboxy oxygen atoms and two nitrogen atoms. Previous studies have analyzed and developed Ln 3+ -EDTA complexes for the purpose of separation and extraction of Ln 3+ .…”

“…Lanthanides (Ln 3+ ) have a high affinity for ligands that contain oxygen donor sites such as multicarboxylate ligands. Oxygen in these ligands has a chelating role and enhances the solubility and stability of the complex. − Furthermore, Ln 3+ complexes with nitrogen and oxygen binding sites have been studied for their enhanced emission properties that could be used for biological imaging. , As a poly­(aminocarboxylate) entity, EDTA mainly forms a 1:1 complex with both divalent and trivalent metal cations through its four carboxy oxygen atoms and two nitrogen atoms. Previous studies have analyzed and developed Ln 3+ -EDTA complexes for the purpose of separation and extraction of Ln 3+ . − …”