Development of luminescent Sm(III) chelates containing hexadentate to nonadentate ligands: synthesis, photophysical properties and coupling to biomolecules

Seventeen novel samarium (Sm)(III) chelates containing two iminodiacetic acid moieties were synthesised and their luminescence properties were measured with the aim of developing new labels for biochemical applications. The chelates contained different numbers of coordinating groups. According to the results obtained, the Sm(III) chelates that are to be used in time-resolved luminescence biochemical assays should be nonadentate in order to have a sufficient lifetime. Chelates having a terpyridine structure in the ligand seem to be promising alternatives. In addition, an equation for the determination of the number of water molecules in the first coordination sphere of Sm(III) ions in the chelate was developed.