Pyridine-based lanthanide complexes combining MRI and NIR luminescence activities

Célia S. Bonnet, Frédéric Buron, Fabien Caillé, Chad M. Shade, Bohuslav Drahoš, Laurent Pellegatti, Jian Zhang, Sandrine Villette, Lothar Helm, Chantal Pichon, Franck Suzenet, Stéphane Petoud, Éva Tóth

Research output: Contribution to journalArticlepeer-review

84 Scopus citations


A series of novel triazole derivative pyridine-based polyamino- polycarboxylate ligands has been synthesized for lanthanide complexation. This versatile platform of chelating agents combines advantageous properties for both magnetic resonance (MR) and optical imaging applications of the corresponding Gd 3+ and near-infrared luminescent lanthanide complexes. The thermodynamic stability constants of the Ln 3+ complexes, as assessed by pH potentiometric measurements, are in the range logK LnL=17-19, with a high selectivity for lanthanides over Ca 2+, Cu 2+, and Zn 2+. The complexes are bishydrated, an important advantage to obtain high relaxivities for the Gd 3+ chelates. The water exchange of the Gd 3+ complexes (k ex 298=7.7-9.3× 106 s -1) is faster than that of clinically used magnetic resonance imaging (MRI) contrast agents and proceeds through a dissociatively activated mechanism, as evidenced by the positive activation volumes (ΔV≠6 =7.2- 8.8 cm 3mol -1). The new triazole ligands allow a considerable shift towards lower excitation energies of the luminescent lanthanide complexes as compared to the parent pyridinic complex, which is a significant advantage in the perspective of biological applications. In addition, they provide increased epsilon values resulting in a larger number of emitted photons and better detection sensitivity. The most conjugated system PheTPy, bearing a phenyl-triazole pendant on the pyridine ring, is particularly promising as it displays the lowest excitation and triplet- state energies associated with good quantum yields for both Nd 3+ and Yb 3+ complexes. Cellular and in vivo toxicity studies in mice evidenced the non-toxicity and the safe use of such bishydrated complexes in animal experiments. Overall, these pyridinic ligands constitute a highly versatile platform for the simultaneous optimization of both MRI and optical properties of the Gd 3+ and the luminescent lanthanide complexes, respectively.

Original languageEnglish (US)
Pages (from-to)1419-1431
Number of pages13
JournalChemistry - A European Journal
Issue number5
StatePublished - Jan 27 2012
Externally publishedYes


  • Bimodal
  • Lanthanides
  • Luminescence
  • Magnetic resonance imaging
  • Near infrared

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry


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