Hydrophilic oxybathophenanthroline ligands: Synthesis and copper(II) complexation

Hydrophilic oxybathophenanthroline dendrons (generation 1 to 3) have been synthesized by treatment of 4,7-bis(4´-hydroxyphenyl)-1,10-phenanthroline with the corresponding bromo-functionalized etheraryl branching units containing triethylene glycol monomethyl end groups. Radiotracer experiments using ⁶⁴Cu prove the rapid formation of stable copper(II) complexes in aqueous solution. These ⁶⁴Cu complexes remain unchanged even upon addition of a high excess of glutathion as competing ligand, thus demonstrating the high stability of the formed copper(II) complexes. Electronic and EPR spectroscopy indicate the formation of [Cu(L)₂(OH₂)₂]²⁺ (L = Ligand) complexes in aqueous solution, confirmed by time-resolved laser fluorescence spectroscopy and supported by molecular mechanics modeling.