Synthesis and Characterization of Linear Luminescent Schiff-Base Polyelectrolytes with Europium(III) in the Backbone1a

The first luminescent linear europium(III) Schiff-base polyelectrolytes with europium in the polymer backbone have been synthesized and characterized. Europium-containing polyelectrolytes with ligand triplet states at or above the 5 D 0 state of europium luminesce with high quantum yields, consistent with the intramolecular energy-transfer mechanism established for europium(III) complexes. New [NaY(tstm)] n polyelectrolytes, where tstm 4- is the anionic ligand derived from N, N ‘, N ‘‘, N ‘‘‘- t etra s alicylidene-3,4,3‘,4‘- t etraaminodiphenyl m ethane, were synthesized with n values (up to 21 600) based on NMR end-group analysis. Intrinsic viscosities provide Mark−Houwink constants of a = 0.52 and K = 0.066 cm 3 /g for [NaY(tstm)] n . Mixed-metal [NaY x Eu 1 - x (tstm)] n polyelectrolytes provide enhanced emission over [NaEu(tstm)] n . The intensity is most enhanced for polyelectrolytes with Y:Eu ratios between 1:2.5 and 1:9, probably by intrachain energy transfer from the yttrium units of the polyelectrolytes to the Eu III ions. [NaY 0.2 Eu 0.8 (tstm)] n (Y:Eu = 1:4) luminesces more strongly than any other compound investigated and has a quantum yield of 0.74 at 77 K.