Ion-selective electrodes based on a pyridyl-containing triazolophane: Altering halide selectivity by combining dipole-promoted cooperativity with hydrogen bonding

Elsayed M. Zahran, Yuran Hua, Semin Lee, Amar H. Flood, Leonidas G. Bachas

Research output: Contribution to journalArticlepeer-review

30 Scopus citations

Abstract

Triazolophanes are ionophores, with preorganized cyclic cavities that have tunable selectivities for halides. The interaction with halides is based on hydrogen bonding between the eight CH hydrogen atoms of the cavity and the halide anion. The rigidity of the cavity in tetraphenylene triazolophane along with the hydrogen bonding favors planar 1:1 complexation of "snugly" encapsulated chloride and bromide. Manipulating the triazolophanes structure by introducing two pyridyl moieties into the cavity alters the receptors binding mode. This change adds a dipole-promoted driving force that combines with hydrogen bonding to favor the formation of 2:1 sandwich complexes around halides. The potentiometric response of electrodes based on this new ionophore was evaluated for optimal halide selectivity. The new triazolophane-based electrode showed an anti-Hofmeister selectivity toward iodide with a submicromolar detection limit. The stoichiometry of complexation and the stability constants with different halides were evaluated using a segmented sandwich membranes method. The pyridyl-triazolophane demonstrated a response consistent with a 2:1 sandwich-type complex with iodide, in polyvinyl chloride (PVC) membranes.

Original languageEnglish (US)
Pages (from-to)3455-3461
Number of pages7
JournalAnalytical Chemistry
Volume83
Issue number9
DOIs
StatePublished - May 1 2011

ASJC Scopus subject areas

  • Analytical Chemistry

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