Synthesis and Luminescence Properties of Self-Assembled Lanthanide Complexes with an EDTA-Type Chelating Ligand in Aqueous Ethanol Solution

Abstract A hexadentate chelating ligand based on ethylenediaminetetraacetic acid (EDTA) with four cholesteryl groups (L2) was designed and synthesized. L2 forms stable 1:1 complexes with lanthanide ions, and the resulting L2-lanthanide complexes form stable self-assemblies with an average particle size of ∼50 nm in aqueous ethanol solution (20 wt%). Under these conditions, the L2-lanthanide complexes exhibit amphiphilic properties and long-lived luminescence. Sodium 2-naphthoate was added as a guest anion to form a 1:2 complex (anion:Ln) with a lanthanide complex resulting in exciton-coupled circular dichroism spectra. 4-Alkyl benzoates were also used as guest anions, and the intensity of the sensitized luminescence largely depends in this case on the length of their alkyl chain.