title: Chloride-selective electrodes based on "two-wall" aryl-extended calix[4]pyrroles: combining hydrogen bonds and anion-π interactions to achieve optimum performance.
abstract: The performance of chloride-selective electrodes based on "two-wall" aryl-extended calix[4]pyrroles and multiwall carbon nanotubes is presented. The calix[4]pyrrole receptors bear two phenyl groups at opposite meso-positions. When the meso-phenyl groups are decorated with strong electron-withdrawing substituents, attractive anion-π interactions may exist between the receptor's aromatic walls and the sandwiched anion. These anion-π interactions are shown to significantly affect the selectivity of the electrodes. Calix[4]pyrrole, bearing a p-nitro withdrawing group on each of the meso-phenyl rings, afforded sensors that display anti-Hofmeister behavior against the lipophilic salicylate and nitrate anions. Based on the experimental data, a series of principles that help in predicting the suitability of synthetic receptors for use as anion-specific ionophores is discussed. Finally, the sensors deliver excellent results in the direct detection of chloride in bodily fluids.
authors.affiliation: Department of Analytical and Organic Chemistry, Rovira i Virgili University, Marcel⋅lí domingo s/n, 43007 Tarragona (Spain); Institute of Chemical Research of Catalonia (ICIQ), Avda. Països Catalans 16, 43007 Tarragona (Spain).
authors.forename: Jad
authors.initials: J
authors.lastname: Sabek
authors.forename: Louis
authors.initials: L
authors.lastname: Adriaenssens
authors.forename: Tomàs
authors.initials: T
authors.lastname: Guinovart
authors.forename: Enrique J
authors.initials: EJ
authors.lastname: Parra
authors.forename: F Xavier
authors.initials: FX
authors.lastname: Rius
authors.forename: Pablo
authors.initials: P
authors.lastname: Ballester
authors.forename: Pascal
authors.initials: P
authors.lastname: Blondeau
keywords: analytical methods; anion-π interactions; hydrogen bonding; ion-selective electrode; nanotubes