p-(1H-phenanthro[9,10-d]imidazol-2-yl)- substituted calix[4]arene, a deep cavity for guest inclusion.
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.
Botana
Enrique
E
Universidad Autónoma de Madrid, Departamento de Química Orgánica, Cantoblanco, 28049-Madrid, Spain.
Nättinen
Kalle
K
Prados
Pilar
P
Rissanen
Kari
K
de Mendoza
Javier
J