Chiroptical features and luminescence behaviour of macrocyclic tetra(4-quinolyl)-complexes: surprising absence of exciton coupling

The C-4-symmetric (S)-tetra(4-quinolyl) tetraamide derivative of dota has b een prepared. The sodium complex has been characterised by X-ray crystallog raphy and although. the quinolyl groups are appropriately oriented for exci ton coupling in the solid-state, in solution no evidence for coupling was f ound for the free ligand nor its protonated, Na, Ca or Eu complexes, Instea d, excimer formation was observed in emission consistent with a coplanar ar rangement of the quinolyl groups.