Within the context of biological imaging, lanthanide-based probes represent a viable alternative to traditional luminescent organic dyes. Trivalent lanthanides possess emission spectra with narrow, distinct bands, and have long luminescence lifetimes, which render them useful for biological imaging. Europium(III) and samarium(III) specifically emit within the 400-700 nm range known colloquially as the “biological window,” wherein there is minimal absorption by biological tissue. However, use of these metals for optical imaging present a unique problem, as excitation of f-f orbital transitions is Laporte and often spin forbidden. Thus, excitation must occur via a small organic sensitizer, ideally directly coordinated to the lanthanide, which populates the excited states of the lanthanide via intersystem crossing followed by energy transfer. Europium and samarium excited states are ideally accessed by organic sensitizers with triplet states of 20,000 cm-1. Prior work in our lab has focused on phenanthroline1 functionalized macrocycles, which exhibit moderate quantum yield with Eu(III) and somewhat limited kinetic inertness in aqueous buffer. In order to enhance the respective quantum yields and complex inertness while retaining complex solubility, we have prepared a small library of picolinate-functionalized chelates. The synthesis, photophysical characterization and their potential to be utilized for optical imaging in concert with Cherenkov radiation mediated energy transfer2 will be presented.

Design, synthesis and characterization of hydrophilic, biocompatible chelators to produce high-quantum yield europium and samarium complexes for optical imaging

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.