Lanthanide complexes as smart CD probes for chirality sensing of biological substrates.

Lanthanide tris(beta-diketonates) and porphyrinates acted as effective circular dichroism (CD) probes for chirality sensing of neutral and zwitterionic guests. They were electrically neutralized but formed highly coordinated 1:1 complexes with various guests. When a chiral, non-chromophoric guest was combined with a chromophoric lanthanide probe, the resulting highly coordinated complex exhibited characteristic CD signal, the sign of which was dependent on the absolute configuration of the bound guest. Since there are wide variations of coordinating ligands and lanthanide centers, lanthanide coordination chemistry offers great possibilities for the design of new CD chirality sensory systems especially for biologically important guests.