Conformation-Controlled Luminescent Properties of Lanthanide Clusters Containing <i>p-tert</i>-Butylsulfonylcalix[4]arene

Dinuclear and cubane-shaped lanthanide cluster complexes containing EuIII and TbIII were synthesized by step-by-step construction using p-tert-butylsulfonylcalix[4]arene as a cluster-forming ligand. The sulfonylcalixarene adopts a pinched-cone conformation in the dinuclear complexes and a cone conformation in the cubane complexes. Because the calixarene has a large π-conjugate system expanding over the entire molecule, it behaves as a good antenna chromophore for UV and near-UV light, and a slight conformational change of the calixarene (from cone to pinched-cone and vice versa) has an effect on the energy levels of excited S1 and T1 states. As a result, selectivity is observed in the luminescent properties of dinuclear and cubane-shaped systems of EuIII and TbIII.