Anion and neutral molecule recognition by electron deficient boranes
<p>This thesis reports on the synthesis of a series of Lewis acidic boranes used as detectors for the cyanide or fluoride ion, and for the activation of molecular oxygen.</p> <p>Chapter III focuses on the formation of monodentate boranes featuring a pendant ferrocenyl moiety. A sys...
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| Formato: | Thesis |
| Idioma: | English |
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2015
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| _version_ | 1826342857500262400 |
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| author | Tirfoin, R |
| author2 | Aldridge, S |
| author_facet | Aldridge, S Tirfoin, R |
| author_sort | Tirfoin, R |
| collection | OXFORD |
| description | <p>This thesis reports on the synthesis of a series of Lewis acidic boranes used as detectors for the cyanide or fluoride ion, and for the activation of molecular oxygen.</p> <p>Chapter III focuses on the formation of monodentate boranes featuring a pendant ferrocenyl moiety. A systematic study of the fluoride and cyanide binding capabilities of isomeric ferrocenyl-functionalized phenyl boranes was conducted <em>via</em> spectroscopic, crystallographic and voltammetric techniques. The synthesis of receptors supported by an indenyl scaffold was also investigated and the binding properties of such systems studied in details. All receptors proved to be competent at binding both cyanide and fluoride in dry solvents; moreover one such indenyl receptor can selectively bind cyanide in aqueous media and signal the binding event by a green-to-red colour change.</p> <p>Chapter IV constitutes an extension of the previous chapter targeting bidentate receptors with an (indenyl)(cyclopentadienyl)iron(II) back bone. A principle objective was the development of systems offering the chelation of fluoride, and hence a measure of selectivity over the more strongly basic cyanide ion. While <em>bis</em>(dimesitylborane) receptors proved to be synthetically inaccessible, a series of phosphine- and phosphonium-borane species was prepared and their comparative F-/CN- binding abilities determined. Thus, while cationic phosphonium boranes favour fluoride binding by employing a bifunctional binding motif, the neutral phosphine boranes exclusively bind cyanide.</p> <p>Chapter V details the activation of molecular oxygen by pentafluorophenyl-boranes in presence of weak reductants featuring a ferrocene unit. The highly Lewis acidic ferrocenyl bis(pentafluorophenyl)borane was initially studied, and its reaction with dry dioxygen shown to generate a (fully characterized) ferrocenium peroxoborate. Similar reactivity was observed for simple metallocenes such as cobaltocene and ferrocene (or even organic reductants) in presence of a strong Lewis acid, with the trapping of the O<sub>2</sub><sup>2</sup>- ion by the borane thought to be a key thermodynamic driving force for the O<sub>2</sub> reduction.</p> |
| first_indexed | 2024-03-06T18:44:36Z |
| format | Thesis |
| id | oxford-uuid:0e11d0ef-bdf9-4336-b8e1-f5923686908d |
| institution | University of Oxford |
| language | English |
| last_indexed | 2025-03-11T23:37:56Z |
| publishDate | 2015 |
| record_format | dspace |
| spelling | oxford-uuid:0e11d0ef-bdf9-4336-b8e1-f5923686908d2025-03-11T14:20:07ZAnion and neutral molecule recognition by electron deficient boranes Thesishttp://purl.org/coar/resource_type/c_db06uuid:0e11d0ef-bdf9-4336-b8e1-f5923686908dChemistry & allied sciencesEnglishOxford University Research Archive - Valet2015Tirfoin, RAldridge, S<p>This thesis reports on the synthesis of a series of Lewis acidic boranes used as detectors for the cyanide or fluoride ion, and for the activation of molecular oxygen.</p> <p>Chapter III focuses on the formation of monodentate boranes featuring a pendant ferrocenyl moiety. A systematic study of the fluoride and cyanide binding capabilities of isomeric ferrocenyl-functionalized phenyl boranes was conducted <em>via</em> spectroscopic, crystallographic and voltammetric techniques. The synthesis of receptors supported by an indenyl scaffold was also investigated and the binding properties of such systems studied in details. All receptors proved to be competent at binding both cyanide and fluoride in dry solvents; moreover one such indenyl receptor can selectively bind cyanide in aqueous media and signal the binding event by a green-to-red colour change.</p> <p>Chapter IV constitutes an extension of the previous chapter targeting bidentate receptors with an (indenyl)(cyclopentadienyl)iron(II) back bone. A principle objective was the development of systems offering the chelation of fluoride, and hence a measure of selectivity over the more strongly basic cyanide ion. While <em>bis</em>(dimesitylborane) receptors proved to be synthetically inaccessible, a series of phosphine- and phosphonium-borane species was prepared and their comparative F-/CN- binding abilities determined. Thus, while cationic phosphonium boranes favour fluoride binding by employing a bifunctional binding motif, the neutral phosphine boranes exclusively bind cyanide.</p> <p>Chapter V details the activation of molecular oxygen by pentafluorophenyl-boranes in presence of weak reductants featuring a ferrocene unit. The highly Lewis acidic ferrocenyl bis(pentafluorophenyl)borane was initially studied, and its reaction with dry dioxygen shown to generate a (fully characterized) ferrocenium peroxoborate. Similar reactivity was observed for simple metallocenes such as cobaltocene and ferrocene (or even organic reductants) in presence of a strong Lewis acid, with the trapping of the O<sub>2</sub><sup>2</sup>- ion by the borane thought to be a key thermodynamic driving force for the O<sub>2</sub> reduction.</p> |
| spellingShingle | Chemistry & allied sciences Tirfoin, R Anion and neutral molecule recognition by electron deficient boranes |
| title | Anion and neutral molecule recognition by electron deficient boranes |
| title_full | Anion and neutral molecule recognition by electron deficient boranes |
| title_fullStr | Anion and neutral molecule recognition by electron deficient boranes |
| title_full_unstemmed | Anion and neutral molecule recognition by electron deficient boranes |
| title_short | Anion and neutral molecule recognition by electron deficient boranes |
| title_sort | anion and neutral molecule recognition by electron deficient boranes |
| topic | Chemistry & allied sciences |
| work_keys_str_mv | AT tirfoinr anionandneutralmoleculerecognitionbyelectrondeficientboranes |