Luminescent Rhenium and Ruthenium Complexes of an Amphoteric Poly(amidoamine) Functionalized with 1,10-Phenanthroline

A new amphoteric copolymer, PhenISA, has been obtained by copolymerization of 4-(4′-aminobutyl)-1,10-phenanthroline (BAP) with 2-methylpiperazine and bis(acrylamido)acetic acid (BAC) (6% of phenanthroline-containing repeating units). The copolymer showed excellent solubility in water, where it self-aggregated to give clear nanoparticle suspensions (hydrodynamic diameter = 21 ± 2 nm, by dynamic light scattering (DLS) analysis). The phenanthroline pendants of the polymer stably coordinated either Re(CO)3+ or Ru(phen)22+ fragments, affording luminescent Re-PhenISA, Re-Py-PhenISA, and Ru-PhenISA polymer complexes, emitting from triplet metal-to-ligand charge transfer (3MLCT) excited states (with λem = 608, 571, and 614 nm, respectively, and photoluminescence quantum yields Φem = 0.7%, 4.8%, and 4.1%, in aerated water solution, respectively). DLS analyses indicated that the polymer complexes maintained the nanosize of PhenISA. All the complexes were stable under physiological conditions (pH 7.4, 0.15 M NaCl) i...