- Unbalanced-Ion-Pair-Catalyzed Nucleophilic Fluorination Using Potassium Fluoride
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An unbalanced ion pair promoter (e.g., tetrabutylammonium sulfate), consisting of a bulky and charge-delocalized cation and a small and charge-localized anion, greatly accelerates nucleophilic fluorinations using easy handling KF. We also successfully converted an inexpensive and commercially available ion-exchange resin to the polymer-supported ion pair promoter (A26–SO42–), which could be reused after filtration. Moreover, A26–SO42– can be used in continuous flow conditions. In our conditions, water is well-tolerated.
- Hammond, Gerald B.,Li, Wangbing,Lu, Zhichao,Xu, Bo
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supporting information
p. 9640 - 9644
(2021/12/14)
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- Active metal template synthesis of a neutral indolocarbazole-containing [2]rotaxane host system for selective oxoanion recognition
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An active metal template strategy was used to synthesise a neutral indolocarbazole containing [2]rotaxane anion host system. 1H NMR anion binding investigations reveal that the [2]rotaxane recognises a range of monoanions in acetone-d5:D2O 95: 5 with an unusual interlocked host selectivity for acetate and dihydrogenphosphate oxoanions over halides. The rotaxane displays an overall selectivity for the sulfate dianion, favouring a 2: 1 host: guest binding stoichiometry at low sulfate concentration and a 1: 1 stoichiometry in the presence of excess sulfate. Fluorescence titration demonstrates that the [2]rotaxane is also capable of sensing guest anions via significant changes in its emission spectrum.
- Brown, Asha,Lang, Thomas,Mullen, Kathleen M.,Beer, Paul D.
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p. 4587 - 4594
(2017/07/10)
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- Unique fluoride anion complexation in basic media by 5,5-dioxophenothiazine bis(phenylurea) and bis(phenylthiourea)
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The anion recognition properties of the newly synthesized 5,5-dioxophenothiazine bis(phenylurea) and bis(phenylthiourea) were investigated in acetonitrile using UV-vis spectroscopy. While most of the studied anions were bound only by the neutral receptors
- Kormos, Attila,Móczár, Ildikó,Pál, Dávid,Baranyai, Péter,Holczbauer, Tamás,Palló, Anna,Tóth, Klára,Huszthy, Péter
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p. 8142 - 8146
(2013/09/02)
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- Anion complexation by triazolium "ligands": Mono- and bis-tridentate complexes of sulfate
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By utilizing click chemistry and methylation, the triazolium motif was employed to design tridentate "ligands" that bind by electron acception instead of electron donation. As electronically inverted ligands they are able to complex sulfate ions by hydrog
- Schulze, Benjamin,Friebe, Christian,Hager, Martin D.,Guenther, Wolfgang,Koehn, Uwe,Jahn, Burkhard O.,Goerls, Helmar,Schubert, Ulrich S.
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supporting information; experimental part
p. 2710 - 2713
(2010/09/05)
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- Molecular Metals with Widely Tunable Band Filling. Structure/Stoichiometry/Counterion Relationships in the Electrochemistry of a Cofacially Joined Polymeric Phthalocyanine Metal
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The oxidative electrochemistry of the cofacially joined phthalocyanine polymer n to yield molecular metals/conductive polymers of the type Xy>n is studied by combination of X-ray diffractometric and spectroscopic techniques.Electrochemical methodology includes controlled-potential coulometry and electrochemical potential spectroscopy (ECPS) applied to rapidly stirred slurries or to microcompactions of the solid polymer.For X(1-)= BF4(1-) in acetonitrile, oxidation ("dopping") of as-polymerized orthorhombic n to yield tetragonal(BF4)y>n (y ca. 0.50) is accompanied by a significant overpotential, minimal tunability in y, and involves a first-order structural phase-transformation.Electrochemical undoping occurs smoothly and over a broader potential range (0.90 V) to afford tetragonal n, which is also accesible by thermally undoping I1.1>n.Once in the more open tetragonal structure, both the electrochemical and diffraction data argue that y (hence, conduction band filling) can be homogeneously/continuously tuned between 0.0 and 0.50.This result verifies the crystal structural basis of the polymer electrochemical "break-in" phenomenon.It also represents the first case in which the band filling of a molecular metal is broadly tunable.In tetrahydrofuran, tetragonal n can also be reversibly n-doped to yield 0.09>n.Oxidative ECPS studies with a number of anions in acetonitrile (PF6(1-), SbF6(1-), tosylate, CF3(CF2)nSO3(1-), n=0,3,7) demonstrate that maximum doping stechiometries achievable (y, hence band filling) are largely a function of anion size, i.e., packing constraints within thetetragonal Xy>n crystal structure.In contrast to these results, ECPS studies of solid Ni(Pc) (monoclinic slipped-stack β phase) reveal a first-order structural transformation to yield tetragonal Ni(Pc)(BF4)y (y ca. 0.48) upon oxidative doping, and a subsequent first-order transformation to another slipped-stack Ni(Pc) structure (monoclinic slipped-stack γ phase) upon undoping.Doping/undoping occurs over a relatively narrow potential range; consequently there is far less tunability in y than in the Xy>n materials, and large overpotentials are observed.ECPS studies of n reveal irreversible oxidative processes, and polymer decomposition via Ge-O bond cleavage is implicated.
- Gaudiello, John G.,Kellogg, Glen E.,Tetrick, Stephen M.,Marks, Tobin J.
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p. 5259 - 5271
(2007/10/02)
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