title: p-(1H-phenanthro[9,10-d]imidazol-2-yl)- substituted calix[4]arene, a deep cavity for guest inclusion.
abstract: The reaction of tetra-p-formyltetra-O-propylcalix[4]arene with phenanthrenequinone in the presence of NH(4)OAc affords compound 2, a new class of calixarene with an expanded aromatic cavity, that could be stabilized by hydrogen-bonded bridges and/or ion pairing, thus preventing collapse into fully stacked pinched cone conformations as depicted. Two partially protonated calixarenes interdigitate in the solid state to give rise to a self-assembled face-to-face dimer, stabilized by pi-pi stacking interactions.
authors.affiliation: Universidad Autónoma de Madrid, Departamento de Química Orgánica, Cantoblanco, 28049-Madrid, Spain.
authors.forename: Enrique
authors.initials: E
authors.lastname: Botana
authors.forename: Kalle
authors.initials: K
authors.lastname: Nättinen
authors.forename: Pilar
authors.initials: P
authors.lastname: Prados
authors.forename: Kari
authors.initials: K
authors.lastname: Rissanen
authors.forename: Javier
authors.initials: J
authors.lastname: de Mendoza