title: pH-Controlled molecular switches and the substrate-directed self-assembly of molecular capsules with a calix[4]pyrrole derivative.
abstract: 10alpha,20alpha-Bis(4-nitrophenyl)calix[4]pyrrole (1) forms 1:1 complexes with anions of selected aromatic hydroxy acids in which the host orientation within the guest is controlled by a change in the pH value. Some bis-anionic guests, including those obtained from 4-hydroxybenzoic acid, 1,4- and 1,3-benzenedicarboxylic acids, induce the self-assembly of molecular capsules involving two molecules of the receptor. (1)H NMR data and solid-state structures of the 1:1 complex of 1 with p-C(6)H(4)(COOH)(COO(-))(+)NMe(4) and the 2:1 capsule [(1)(2)m-C(6)H(4)(COO(-))(2)((+)NMe(4))(2)] provide structural details in solution and in the solid state.
authors.affiliation: Dipartimento di Chimica Organica e Biologica, Università di Messina, Salita Sperone 31, 98166 Messina, Italy.
authors.forename: Grazia
authors.initials: G
authors.lastname: Cafeo
authors.forename: Franz H
authors.initials: FH
authors.lastname: Kohnke
authors.forename: Luca
authors.initials: L
authors.lastname: Valenti
authors.forename: Andrew J P
authors.initials: AJ
authors.lastname: White