Chiral Sensing Using Circularly Polarized Luminescence of Bis(phenanthroline dicarboxylic acid) Eu III Complex Induced by Allosteric-type Interaction with Amino Acid Molecules

• Published in: Chemistry, an Asian journal an Asian journal, 2019-02, Vol.14 (4), p.561-567
• Main Authors: Iwamura, Munetaka, Fujii, Mai, Yamada, Ayano, Koike, Hikaru, Nozaki, Koichi
• Format: Article
• Language: English
• ISSN: 1861-4728; 1861-471X
• DOI: 10.1002/asia.201801777

[Eu(pda) ] and [Eu(bda) ] (pda=1,10-phenanthroline-2, 9-dicarboxylic acid; bda=2,2' bipyridine 5,5'-dicarboxylic acid) have an achiral D structure in crystals. These complexes exhibit circularly polarized luminescence (CPL) in water containing chiral amino acids. In this work, induced CPL of [Eu(pda) ] and [Eu(bda) ] in water solutions containing a mixture of d- and l- amino acids were examined. Plots of g values of the induced CPL as a function of mol-fraction of l- and d- arginine reveal that [Eu(pda) ] favors homo-association ([Eu(pda) ] -(l-arginine) or [Eu(pda) ] -(d-arginine) ) over hetero-association {[Eu(pda) ] -(l-arginine)⋅(d-arginine)}. This suggests that association of an arginine molecule induces a structural change in [Eu(pda) ] to promote chiral selective association to another arginine, i.e., homo-allosteric association. On the other hand, the system of [Eu(pda) ] with histidine favors hetero-allosteric association over homo-association. No allosteric effect is recognized in CPL from [Eu(bda) ] .