Trevor John Wear

ANION AND CATION RECOGNITION BY NEW MONO- AND BIS-RUTHENIUM(II) BIPYRIDYL CROWN ETHER RECEPTOR MOLECULES

Abstract Novel aza crown and dibenzocrown ether mono- and bis-ruthenium(II) bipyridyl amide-containing receptors have been synthesized and their preliminary Group 1 metal cation and halide anion complexing properties investigated. 1 H NMR coordination studies have shown the receptors bind potassium cations in their respective crown ether recognition sites. Chloride anion coordination studies reveal that those receptors containing secondary amide CONH groups can complex and electrochemically sense chloride anions through a combination of electrostatic attraction and favourable amide CONH—anion hydrogen bonding interactions. Stability constant determinations from NMR titration data and electrochemical observations suggest, with receptor [Ru 2 L 6 (bipy) 4 ][PF 6 ] 4 , aza crown ether complexed potassium cations in combination with an amide-linked positively charged ruthernium(II) bipyridyl moiety can cooperatively enhance the strength of chloride anion complexion. In addition, fluorescence emission spectral studies show that the relative emission intensities of the metal-to-ligand charge transfer emission bands of the secondary amide-containing receptors are increased in the presence of chloride anions. Copyright C 1996 Elsevier Science Ltd

SPECTRAL AND ELECTROCHEMICAL HALIDE ANION RECOGNITION BY ACYCLIC RUTHENIUM(II) 5,5'-BIS-AMIDE SUBSTITUTED BIPYRIDYL RECEPTOR MOLECULES

A series of new acyclic ruthenium(II) 5,5′-bis-amide substituted 2,2′-bipyridyl receptor molecules have been synthesized. 1H NMR spectroscopy, cyclic and square wave voltammetry, electronic absorption and fluorescence-emission spectroscopic measurements have demonstrated the spectral and electrochemical recognition of chloride, and spectral recognition of bromide anions in polar solvents.

Chloride anion recognition by neutral platinum(II) and palladium(II) 5,5′-bis-amide substituted bipyridyl receptor molecules

Abstract A series of new acyclic platinum(II) and palladium(II) 5,5′-bis-amide substituted 2,2′-bipyridyl receptors have been synthesized and single-crystal structural investigations of two receptors are described. Proton NMR anion binding studies reveal that these neutral receptors recognize chloride anions in dimethyl sulfoxide solution

Spectral and electrochemical recognition of halide anions by acyclic mononuclear ruthenium(II) bipyridyl receptor molecules

New acyclic mononuclear ruthenium(II) bipyridyl amide receptors containing phenolic and sterically bulky tert-butyl pendant arms have been prepared and characterised. Spectroscopic and electrochemical anion-co-ordination studies have shown these receptors to bind chloride, bromide and iodide anions via a combination of electrostatic attraction and favourable amide CONH and phenolic ROH hydrogen-bonding interactions. Stability constant determinations from NMR titration data and electrochemical observations indicate that the presence of additional phenolic hydrogen-bonding units significantly enhances the strength of anion complexion. In addition, incorporation of sterically bulky tert-butyl groups to the amide units confers improved selectivity for chloride over iodide anions. Fluorescence-emission spectroscopic studies show that the relative emission intensities of the metal-to-ligand charge-transfer emission bands of the receptors is enhanced in the presence of chloride and bromide but diminished by iodide anions.

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.

NOVEL ANION BINDING SELECTIVITY TRENDS EXHIBITED BY NEW DINUCLEAR RHENIUM(I), RUTHENIUM(II) AND OSMIUM(II) BIPYRIDYL CLEFT-TYPE RECEPTORS

Novel dinuclear rhenium(I), ruthenium(II) and osmium(II) bipyridyl cleft-type receptor systems exhibit remarkable selectivity for dihydrogenphosphate over halide anions dictated by the nature of the bridging linkage and the transition-metal Lewis-acidic centre.

Selective electrochemical recognition of the dihydrogen phosphate anion in the presence of hydrogen sulfate and chloride ions by new neutral ferrocene anion receptors

New neutral ferrocene anion receptors L3, L4, L5 selectively complex, electrochemically recognise and respond to the dihydrogen phosphate guest anion in the presence of excess amounts of hydrogen sulfate and chloride anions.

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 ruthenium(II) bipyridyl-polypyridinium receptors

New acyclic ruthenium(II) bipyridyl-pyridinium receptor molecules have been synthesised. 1H NMR spectroscopy, and cyclic and square wave voltammetry have established these receptors complex and electrochemically sense the chloride anion. Disappointingly spectral detection of halide anions by electronic absorption and fluorescence-emission spectroscopic measurements was unsuccessful.

Anion recognition by novel ruthenium(II) bipyridyl calix[4]arene receptor molecules

Exotic calix[4]arene mono- and di-topic anion receptors containing one and two ruthenium(II) bipyridyl moieties have been prepared and shown by 1H NMR and CV to bind and electrochemically recognise halide, dihydrogen phosphate and hydrogen sulphate anions. The monotopic calix[4]arene anion receptor 8 selectively electrochemically recognises H2PO4– in the presence of tenfold excess amounts of HSO4– and Cl–.