Christopher Peter Moore

Optical Thin-Film Sensors for the Determination of Aqueous Halide Ions

Fourteen thin-film optical sensors in which halide-sensitive fluorophores are immobilized in a thin copolymer film (≍50 μm, dry) have been developed and characterized. The sensor films use rhodamine, 6-methoxyquinoline, and harmane dyes which have been functionalized and bound to a hydrophilic copolymer. The sensor films are reversibly capable of determining aqueous bromide and iodide with ≍4 and 2% accuracy, respectively, at concentrations of around 10−3 mol dm−3, and are more sensitive than previous plastic sensor fabrications. The 90% response time to molar iodide is ≍30–60 s. A combination of sensor films allows the simultaneous determination of both I− and Br− in a mixed-halide solution. The interference of several ions, including pseudo-halides, on the sensor films has been studied.

Copper(I) and silver(I) homometallic complexes of new bis(2,2′-bipyridine) ligands

New ligand systems containing two 2,2′-bipyridin-6-ylmethyl moieties linked via 1,4,10,13-tetraoxa-7,16-diazacyclooctadecane, 1,4,10,13-tetrathia-7,16-diazacyclooctadecane, 4,4′-bipyridinediium, N,N′,N″-tritosyldiethylenetriamine and toluene-p-sulfonamide spacer units have been prepared. A variety of homometallic Copper(I) complexes have been isolated and fast atom bombardment mass spectrometry investigations suggest most of the complexes to be of general formula [Cu2L2][PF6]2. Solution 1H NMR spectra of these species imply the existence of additional complex components of 1 : 1 L : copper(I) ratio. A variety of mono- and bi-metallic silver(I) complexes were also isolated with these ligands.

New fluorescent indolium and quinolinium dyes for applications in aqueous halide sensing

Abstract Bromide and teraphenylborate salts of six new highly fluorescent dyes, produced by the reaction of two heterocyclic nitrogen bases with 8-bromo-octanoic acid, 11-bromo-undecanoic acid and 15-bromo-pentadecanoic acid have been prepared. Unlike the bases themselves, the quaternary salts are water soluble and have fluorescence characteristics independent of pH in the pH range 7–11. Both the fluorescence intensity and fluorescence lifetime of these dyes are reduced in the presence of aqueous halide ions, allowing halide concentrations to be determined accurately at concentrations of importance to both medicine and industry. All the dyes have been characterised in terms of steady state fluorescence spectra and steady-state Stern-Volmer analysis. The Stern–Volmer constants, ( K SV ), for the dyes are compared to those obtained for some commercially available dyes. The prospects for using these dyes in halide sensor devices are discussed.

Halide anion recognition by new acyclic quaternary polybipyridinium and polypyridinium receptors

New acyclic quaternary polybipyridinium receptors containing 5,5′- and 4,4′-disubstituted N,N′-dimethyl-2,2′-bipyridinium moieties (L1–L6) and a polypyridinium receptor L7 have been synthesised. 1H NMR titration studies in deuteriated DMSO show these receptors complex chloride and bromide anions, with a 1:1 stoichiometric ligand: chloride stability constant evaluations suggesting the amide containing polypyridinium receptor (L7) forms the most thermodynamically stable chloride anion complex. Square-wave voltammetric investigations showed some of the polypyridinium receptors to recognise electrochemically the chloride anion.