Synthesis and Characterization of a Luminescent Cyclic Poly(ethylene oxide)-Polypyridyl Ruthenium Complex

We report the synthesis of a macrocyclic poly(ethyleneoxide) (PEO)connected by one [Ru(bpy)(3)](2+) unit (where bpy= 2,2 & PRIME;-bipyridine), a photoactive metal complex that providesphotosensitivity and potential biomedical applications to this polymerstructure. The PEO chain provides biocompatibility, water solubility,and topological play. The macrocycles were successfully synthesizedby copper-free click cycloaddition between a bifunctional dibenzocyclooctyne(DBCO)-PEO precursor and 4,4 & PRIME;-diazido-2,2 & PRIME;-bipyridine,followed by complexation with [Ru(bpy)(2)Cl-2].The cyclic product accumulated efficiently in MCF7 cancer cells andexhibited a longer fluorescence lifetime than its linear analogue,likely due to differences in the accessibility of the ligand-centered/intraligandstates of Ru polypyridyls in both topologies.