Synthesis, Chirality and Complexation Phenomena of Two Diastereoisomeric Dinuclear Lanthanide(III) Complexes

Two diastereoisomeric ditopic ligands have been synthesised by linking (SSS)-heptadentate triamide derivative of cyclen with a central (SS)- or (SR)-1,2-diphenyl-1,2-diaminoetbane derivative. Complexes of selected Ln(III) ions (Ln = Eu, Tb, Yb) have been characterized and circularly polarised luminescence spectra of the Eu systems revealed significant differences, consistent with a change in overall complex chirality associated with the local helicity at the metal centre. Stepwise binding constants for the formation of 1:1 and 2:1 ternary adducts with (S)-lactate and (S)-O-phospho-tyrosine have been determined by least-squares analysis of spectral titration data, and emission and H-1 NMR spectroscopic data compared with the mononuclear analogue.