Metal-Controlled Diastereoselective Self-Assembly and Circularly Polarized Luminescence of a Chiral Heptanuclear Europium Wheel

The chiral dissymmetric tetradentate ligand (S)-6′-(4-phenyloxazolin-2-yl)-2,2′-bipyridine-6-carboxylate
(S-Phbipox) leads to the diastereoselective assembly of a homochiral
Eu3+ triangle and a highly emissive (quantum yield = 27%)
heptanuclear wheel that is the largest example of a chiral luminescent
complex of Eu3+ reported to date. The nuclearity of the
assembly is controlled by the solvent and the Eu3+ cation.
All of the compounds show large circularly polarized luminescence
with an activity that varies with the nature of the assembly (highest
for the homochiral trimer).