Importance of hydrogen-bonding sites in the chiral recognition mechanism between racemic D3 terbium(III) complexes and amino acids.
The perturbation of the racemic equilibrium of luminescent D3 terbium(III) complexes with chelidamic acid (CDA), a hydroxylated derivative of 2,6-pyridine-dicarboxylic acid (DPA), by added chiral biomolecules such as L-amino acids has been studied using circularly polarized luminescence and 13C NMR spectroscopy. It is shown in this work that the chiral-induced equilibrium shift of [Tb(CDA)3](6-) by L-amino acids (i.e. L-proline or L-arginine) was largely influenced by the hydrogen-bonding networks formed between the ligand interface of racemic [Tb(CDA)3](6-) and these added chiral agents. The capping of potential hydrogen-bonding sites by acetylation in L-proline led to a approximately 100-fold drop in the induced optical activity of the [Tb(CDA)3](6-):N-acetyl-L-proline system. This result suggested that the hydrogen-bonding networks serve as the basis for further noncovalent discriminatory interactions between racemic [Tb(CDA)3](6-) and added L-amino acids.
Moussa
Ahmed
A
Department of Chemistry, San José State University, One Washington Square, San José, California 95192-0101, USA.
Pham
Christine
C
Bommireddy
Shruthi
S
Muller
Gilles
G
D001120:Arginine / Q000737:chemistry*; D006860:Hydrogen Bonding; D015394:Molecular Structure; D055668:Photochemical Processes; D010848:Picolinic Acids / Q000737:chemistry; D011392:Proline / Q000737:chemistry*; D011728:Pyridones / Q000737:chemistry; D013725:Terbium / Q000737:chemistry*
D010848:Picolinic Acids; D011728:Pyridones; D013725:Terbium; C042436:chelidamic acid; D001120:Arginine; D011392:Proline; C004860:dipicolinic acid