Abstract
A new ligand based on a p-tert-butylcalix[4]arene functionalised with three 6-carboxylato-2,2′-bipyridine arms reacted with lanthanide(III) cations to form 2:2 complexes in the solid state, whereas in solution, a concentration-dependent equilibrium is observed between 2:2 and 1:1 species, as evidenced by ES-MS and metal luminescence measurements. In the X-ray molecular structure of the terbium complex two branched calixarene platforms share one pendant arm in order to provide a neutral dimeric structure which is held together by a strong hydrogen bonded network together with efficient π–π stacking of two pyridine rings belonging to each ligand.
Acknowledgements
We thank the Centre National de la Recherche Scientifique and the French Ministère des Affaires Etrangères (Projet Galilée) for financial support, the MURST (Ministero dell'Università e della Ricerca Scientifica e Tecnologica, Italy) and the CRUI (Conferenza dei rettori delle Università Italiane, Progetto Galileo).