title: A Poly(9-Borafluorene) Homopolymer: An Electron-Deficient Polyfluorene with "Turn-On" Fluorescence Sensing of NH3 Vapor.
abstract: A substituted poly(9-borafluorene) (P9BF) homopolymer, a boron congener of polyfluorene, is prepared by Yamamoto coupling of a triisopropylphenyl substituted borafluorene (1). As predicted by prior density functional theory (DFT) studies, P9BF has a reduced optical bandgap (Eg,opt = 2.28 eV) and a significantly lowered LUMO level (-3.9 eV, estimated by cyclic voltammetry (CV)) compared to polyfluorene. In addition to binding fluoride in solution, films of P9BF exhibit a reversible, simultaneous turn-off/turn-on fluorescence response to NH3 vapor. A 9-borafluorene-vinylene copolymer (P9BFV) is synthesized via Stille coupling, demonstrating that 1 can readily be incorporated into copolymers. The extended conjugation of P9BFV due to the inclusion of the vinylene group results in a reduced optical bandgap (2.12 eV) and LUMO (-4.0 eV, estimated by CV) compared to the homopolymer P9BF.
authors.affiliation: Department of Chemistry, The University of Alabama, Tuscaloosa, AL, 35487-0036, USA.
authors.forename: Ian A
authors.initials: IA
authors.lastname: Adams
authors.affiliation: Department of Chemistry, The University of Alabama, Tuscaloosa, AL, 35487-0036, USA.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Rupar
mesh_terms: D000641:Ammonia / Q000032:analysis*; D004583:Electrons; D005449:Fluorenes / Q000737:chemistry*; D005740:Gases / Q000032:analysis; D011108:Polymers / Q000737:chemistry*; D011789:Quantum Theory; D013050:Spectrometry, Fluorescence
chemical_list: D005449:Fluorenes; D005740:Gases; D011108:Polymers; D000641:Ammonia
keywords: boron; conjugated polymers; inorganic polymers; polyfluorenes; sensors