Complexation Behavior of Pinene–Bipyridine Ligands towards Lanthanides: The Influence of the Carboxylic Arm
Atena B. Solea,
Liangru Yang,
Aurelien Crochet,
Katharina M. Fromm,
Christophe Allemann,
Olimpia Mamula
Affiliations
Atena B. Solea
Haute Ecole d’Ingénierie et d’Architecture Fribourg, HEIA-FR, HES-SO, University of Applied Sciences of Western Switzerland, Pérolles 80, CH-1705 Fribourg, Switzerland
Liangru Yang
School of Chemistry & Chemical Engineering, Henan University of Technology, Zhengzhou 450001, China
Aurelien Crochet
Department of Chemistry, University of Fribourg, Chemin du Musée 9, CH-1700 Fribourg, Switzerland
Katharina M. Fromm
Department of Chemistry, University of Fribourg, Chemin du Musée 9, CH-1700 Fribourg, Switzerland
Christophe Allemann
Haute Ecole d’Ingénierie et d’Architecture Fribourg, HEIA-FR, HES-SO, University of Applied Sciences of Western Switzerland, Pérolles 80, CH-1705 Fribourg, Switzerland
Olimpia Mamula
Haute Ecole d’Ingénierie et d’Architecture Fribourg, HEIA-FR, HES-SO, University of Applied Sciences of Western Switzerland, Pérolles 80, CH-1705 Fribourg, Switzerland
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. The association constants of the mononuclear complexes determined from the UV-Vis titrations indicated that the ligand (–)-HL1 possessing a shorter carboxylic arm formed more stable complexes compared with (–)-HL2, whose carboxylic arm had one more methylene unit. This is due to the formation of more stable seven-member metal chelate rings in the first case as compared with the eight-member metal chelate rings in the second. IR and fluorescence spectroscopy provided additional information about the structure of these complexes.
