Lanthanide tris(ß-diketonates) as useful probes for chirality determination of biological amino alcohols in vibrational circular dichroism: ligand to ligand chirality transfer in lanthanide coordination sphere.

A series of lanthanide tris(ß-diketonates) functioned as useful chirality probes in the vibrational circular dichroism (VCD) characterization of biological amino alcohols. Various chiral amino alcohols induced intense VCD signals upon ternary complexation with racemic lanthanide tris(ß-diketonates). The VCD signals observed around 1500 cm(-1) (ß-diketonate IR absorption region) correlated well with the stereochemistry and enantiomeric purity of the targeted amino alcohol, while the corresponding monoalcohol, monoamine, and diol substrates induced very weak VCD signals. The high-coordination number and dynamic property of the lanthanide complex offer an effective chirality VCD probing of biological substrates.

Induced circular-dichroism chirality probes for selective amino acid detection through screening of a dynamic combinatorial library of lanthanide complexes.

A dynamic combinatorial library of lanthanide complexes was prepared to develop induced-circular-dichroism (CD) chirality probes. It totaled 168 combinations of coordinative N-aromatic chromophores, trivalent lanthanide centers, and guest amino acids. Eu(3+) and Tb(3+) complexes prepared with quinolinecarboxylic acid were particularly effective as induced-CD chirality probes for selective alanine detection, whereas a Yb(3+) complex with terpyridine exhibited glutamine selectivity. The former two complexes highly preferred alanine to the corresponding amine, ester, amino alcohol, and carboxylic acid derivatives. As such, the present combinatorial screening of a dynamic lanthanide complex library has led to a new series of induced-CD chirality probes for specific amino acids.