Molecular acrobatics: self-assembly of calixarene-porphyrin cages.
Calix[4]arenes equipped with two and four zinc porphyrins have been prepared, and they show remarkable flexibility in their self-assembly properties with the bidentate ligand DABCO. The calix-bisporphyrin forms a 2:2 complex with DABCO, generating a large cavity that has the potential to act as a supramolecular host. The calix-tetraporphyrin, on the other hand, forms four different complexes with DABCO depending on the stoichiometry and concentration. During the course of a titration, all four complexes are populated, leading to large conformational changes and the formation of both intramolecular and intermolecular calix-tetraporphyrin-DABCO sandwich complexes. The system was fully characterized using a combination of UV-visible and (1)H NMR spectroscopy to identify the complexes. At a calix-tetraporphyrin:DABCO ratio of 2:4, the major species is dimeric cage assembly that features a large internal cavity for guest complexation.
Baldini
Laura
L
Dipartimento di Chimica Organica e Industriale, Universitá di Parma, Italy.
Ballester
Pablo
P
Casnati
Alessandro
A
Gomila
Rosa M
RM
Hunter
Christopher A
CA
Sansone
Francesco
F
Ungaro
Rocco
R