Synthèse,Relaxivité et Luminescence de complexes de lanthanides dérivés de ligands ditopiques et assemblages supramoléculaires

Lanthanide elements display many remarkable and exciting propertieswhich explain their widespread use in a number of very important biomedical tools like efficient MRI contrast agents or luminescent probes for highly sensitive assays of bioanalytes amongst other fields of application. In this context, the aim of the present work was to prepare and characterize lanthanide complexes of two ligands that feature a linear or a macrocyclic chelating unit compactly grafted onto a 1,10-phenanthroline derived moiety (phenDTPA and PhenHDO3A). The ditopic nature of the ligands allows the selective incorporation of a d6 metal ion and a lanthanide one in close proximity. The resulting rigidheterobimetallic supramolecular species show useful properties and constitutepotential MRI contrast agents or new luminescent compounds depending on thetype of the lanthanide and transition metal ions employed: for example, the selfassembly process of gadolinium(III) chelates around an iron(II) ion brings aremarkable increase of their relaxivity, a key parameter for use in MRI. On the other hand, association of a ruthenium and and a near infrared emitting 4f ion like ytterbium(III) gives mixed d-f structures able to harvest visible light and convert it into near infra-red signal. Visible light luminescent pH probes were also obtained with Eu3+ or Tb3+ phenHDO3A complexes.