These are luminescent lanthanide complexes that have excellent photophysical properties that make them ideal for use in bioanalytical assays and biological imaging applications. These near-infrared (NIR) emitting luminophores show very high quantum yields and long luminescence lifetimes that are compatible with aqueous environments. Although lanthanides have several advantages over traditional fluorophores, their practical application is hampered by their low absorption coefficients and non-radiative deactivation, both of which lead to very low signal generation. To overcome this limitation, lanthanide ions are encapsulated in organic molecules that serve to absorb light and transfer this excitation to the metal ion, and to prevent its luminescence from being quenched by non-radiative decay.
Highly Luminescent Lanthanide Metallacrown Complexes
Researchers in the Department of Chemistry at the University of Michigan developed lanthanide metallacrown complexes that have very high NIR luminescence efficiency. These lanthanide complexes were synthesized and their quantum yields were measured in the solid state and in methanol. The quantum yields for Nd3+ and Er3+ complexes are the highest reported to date among lanthanide compounds with organic ligands. The versatility of the structure and synthesis allows tuning of the excitation wavelength by changing the organic ligand sensitizer. Different lanthanide metal ions can be incorporated to allow for multiplexed analysis, or to design unique barcodes for tracking and identification applications. These NIR emitting complexes can be especially useful in imaging of biological tissues as they do not absorb light at these wavelength ranges.
Applications • Bioanalytical assays • Biological imaging • Telecommunications • Solar cells • Barcodes
Advantages • High luminescence efficiency • High quantum yields • Near-infrared emission • Narrow bandwidths • Long luminescence lifetimes