Resonance energy transfer from quinolinone modified polystyrene-block-poly(styrene-alt-maleic anhydride) copolymer to terbium(III) metal ions

Polystyrene-block-poly(styrene-alt-maleic anhydride) was synthesized by nitroxide mediated radical polymerization and modified with 7-amino-4-methylquinolin-2(1H)-one (I) and methanol. The formed block polymer ligand contained a quinolinone fluorophore (Ω) and carboxyl (III) or sodium carboxylate (IV) binding sites. The ligand-to-metal resonance energy transfer (RET) and ligand binding properties of [III–Tb3+] and [IV–Tb3+] complexes were investigated by steady-state and time-resolved luminescence spectroscopy in tetrahydrofuran/methanol and/or tetrahydrofuran/deuterated methanol mixtures and compared with those of a low-molecular-weight model ligand, i.e. the sodium salt of N-(4-methyl-2-oxo-1,2-dihydroquinolin-7-yl)succinamic acid (II). The long-lived emission intensities of Tb3+ at 490, 545, 585, and 620nm corresponding to the 5D4→7F6, 5D4→7F5, 5D4→7F4, and 5D4→7F3 transitions, respectively, were strongly increased by the addition of ligands in the order [II-Tb3+]⪡[III-Tb3+]