Luminescent Terbium Complexes with Polymer Ligands

Alternating and statistical copolymers of 9-vinylcarbazole with diethyl fumarate (1), diethyl maleate (2), methacrylic acid (3), maleic anhydride (4), or maleic acid (5) were synthesized and characterized. These copolymers were tested as polymer ligands, that might be able to suppress the environmental vibronic quenching of a lanthanide ion and, simultaneously, to function as energy donors in the ligand-to-metal energy transfer processes. Time-resolved luminescence of a series of [Tb(III)-ligand] complexes in common and deuterated solvents revealed that the complexing properties of copolymers 3 or 5 are stronger than those of 1 or 2. Consequently, the strong binding affinity decreases the ligand-metal (donor-acceptor) distance and gives rise to an efficient ligand-to-metal energy transfer. Thus, the intensities of the long-lived emission (5D4→7F6, 5D4→7F5, 5D4→7F4, 5D4→7F3) of the [Tb(III)-3], [Tb(III)-5], and [Tb(III)-1] or [Tb(III)-2] complexes were found to be eight times, five times, and less than twice that of uncomplexed Tb3+, respectively.