Complexation Behavior of Pinene–Bipyridine Ligands towards Lanthanides: The Influence of the Carboxylic Arm

The complexation behavior of two novel, chiral pinene–bipyridine-type ligands ((–)-HL1 and (–)-HL2) containing a carboxylic arm towards lanthanide Ln(III) (Ln = La, Eu, Lu) ions was investigated through spectroscopic methods. association constants the mononuclear complexes determined from UV-Vis titrations indicated that ligand (–)-HL1 possessing shorter formed more stable compared with (–)-HL2, whose had one methylene unit. This is due to formation seven-member metal chelate rings in first case as eight-member second. IR fluorescence spectroscopy provided additional information about structure these complexes.