Symmetric CEST-active lanthanide complexes for redox monitoring.

Two symmetric ligands harbouring two TEMPO radicals and two functionalized acetamide arms (R = OMe (L1), CF (L2)) were prepared and chelated to lanthanide ions (Eu, Yb for both L1 and L2, Dy for L1). Luminescence measurements on the europium complexes support the coordination of a single water molecule. The TEMPO arms are magnetically interacting in L1 (and its complexes) but not in L2.

Lanthanide Complexes (Gd and Eu ) Based on a DOTA-TEMPO Platform for Redox Monitoring via Relaxivity.

Three lanthanide complexes (Ln=Gd, Eu) based on a DO3 A ([Ln(L )]) or DO2 A ([Ln(L )] ) platform appended by a redox active TEMPO-based arm were prepared. Complex [Ln(L )] shows an alkyne arm, offering the possibility of postfunctionalization by click reaction to yield [Ln(L )] . The complexes demonstrate a redox response whereby the hydroxylamine, nitroxide and oxoammonium forms of the arm can be obtained in turn.

Luminescent pro-nitroxide lanthanide complexes for the detection of reactive oxygen species.

The DOTA-based ligand H3L (5) appended with a pro-nitroxide moiety has been synthesized. The europium and ytterbium complexes 5Ln show metal-centred luminescence. They react with ROS in aqueous media to give a transient iminonitroxide and a stable nitronylnitroxide radical authenticated by EPR, with change in luminescence.