Moussa Ahmed, Pham Christine, Bommireddy Shruthi, Muller Gilles
Department of Chemistry, San José State University, One Washington Square, San José, California 95192-0101, USA.
Chirality. 2009 May;21(5):497-506. doi: 10.1002/chir.20628.
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 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 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: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 and added L-amino acids.
