title: Design of Redox/Radical Sensing Molecules via Nitrile Imine-Mediated Tetrazole-ene Cycloaddition (NITEC).
abstract: The current study introduces a novel synthetic avenue for the preparation of profluorescent nitroxides via nitrile imine-mediated tetrazole-ene cycloaddition (NITEC). The photoinduced cycloaddition was performed under metal-free, mild conditions allowing the preparation of a library of the nitroxide functionalized pyrazolines and corresponding methoxyamines. High reaction rates and full conversion were observed, with the presence of the nitroxide having no significant impact on the cycloaddition performance. The formed products were investigated with respect to their photophysical properties in order to quantify their "switch on/off" behavior. The fluorescence quenching performance is strongly dependent on the distance between the chromophore and the free radical spin as demonstrated theoretically and experimentally. Highest levels of fluorescence quenching were achieved for pyrazolines with the nitroxide directly fused to the chromophore. Importantly, the pyrazoline profluorescent nitroxides were shown to efficiently act as sensors for redox/radical processes.
authors.affiliation: †School of Chemistry, Physics and Mechanical Engineering, Faculty of Science and Technology, Queensland University of Technology, Queensland 4001, Australia.|‡Preparative Macromolecular Chemistry, Institut für Technische Chemie und Polymerchemie, Karlsruhe Institute of Technology (KIT), Engesserstr. 18, 76131 Karlsruhe, Germany.|#Institut für Biologische Grenzflächen, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.
authors.forename: Paul
authors.initials: P
authors.lastname: Lederhose
authors.affiliation: §ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry, The Australian National University, Canberra, ACT 2601, Australia.
authors.forename: Naomi L
authors.initials: NL
authors.lastname: Haworth
authors.affiliation: †School of Chemistry, Physics and Mechanical Engineering, Faculty of Science and Technology, Queensland University of Technology, Queensland 4001, Australia.
authors.forename: Komba
authors.initials: K
authors.lastname: Thomas
authors.affiliation: †School of Chemistry, Physics and Mechanical Engineering, Faculty of Science and Technology, Queensland University of Technology, Queensland 4001, Australia.
authors.forename: Steven E
authors.initials: SE
authors.lastname: Bottle
authors.affiliation: §ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry, The Australian National University, Canberra, ACT 2601, Australia.
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Coote
authors.affiliation: †School of Chemistry, Physics and Mechanical Engineering, Faculty of Science and Technology, Queensland University of Technology, Queensland 4001, Australia.|‡Preparative Macromolecular Chemistry, Institut für Technische Chemie und Polymerchemie, Karlsruhe Institute of Technology (KIT), Engesserstr. 18, 76131 Karlsruhe, Germany.|#Institut für Biologische Grenzflächen, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.
authors.forename: Christopher
authors.initials: C
authors.lastname: Barner-Kowollik
authors.affiliation: †School of Chemistry, Physics and Mechanical Engineering, Faculty of Science and Technology, Queensland University of Technology, Queensland 4001, Australia.
authors.forename: James P
authors.initials: JP
authors.lastname: Blinco
mesh_terms: D003500:Cyclization; D005609:Free Radicals / Q000737:chemistry; D007097:Imines / Q000737:chemistry*; D015394:Molecular Structure; D009570:Nitriles / Q000737:chemistry*; D009589:Nitrogen Oxides / Q000138:chemical synthesis* / Q000737:chemistry; D010084:Oxidation-Reduction; D013777:Tetrazoles / Q000737:chemistry*
chemical_list: D005609:Free Radicals; D007097:Imines; D009570:Nitriles; D009589:Nitrogen Oxides; D013777:Tetrazoles