Sensitization of Eu(III) luminescence by donor-phenylethynylfunctionalized DTPA and DO3A macrocycles

Abstract

The synthesis and complexation to Eu(III) of two macrocyclic ligands functionalized donor-phenylethynyl-moieties as sensitizer is presented. The two ligands based on DTPA bis-amide ([Eu(L1)]) and DO3A ([Na][Eu(L 2)]) have been chosen because of their increased stability in water for potential applications as luminescent bioprobes for one-or twophoton excited scanning microscopy. The DTPA and DO3A ligands possess oxygen or sulfur donor atoms, respectively, connected to a triethyleneglycol (PEG) chain to ensure the water solubility. The optical properties were studied and reveal that ([Eu(L1)]) present a lower brightness than the ([Na][Eu(L 2)]) counterpart because of its inner sphere water molecule coordination that quenches the emission. On the other hand, [Na][Eu(L 2)] exhibits excellent spectroscopic properties with high quantum yield φ = 0.284, and brightness B = 10,220M-1cm -1(defined as e.φ). Unfortunately, the two-photon crosssection of this last complex was measured to be only 4 GM limiting its potential applications to linear microscopy. © 2010 Académie des sciences. Published by Elsevier Masson SAS. All rights reserved.