Journal articles: 'Anions (Chemistry)'

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Černý, Radovan, Matteo Brighi, and Fabrizio Murgia. "The Crystal Chemistry of Inorganic Hydroborates." Chemistry 2, no. 4 (September 29, 2020): 805–26. http://dx.doi.org/10.3390/chemistry2040053.

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The crystal structures of inorganic hydroborates (salts and coordination compounds with anions containing hydrogen bonded to boron) except for the simplest anion, borohydride BH4−, are analyzed regarding their structural prototypes found in the inorganic databases such as Pearson’s Crystal Data [Villars and Cenzual (2015), Pearson’s Crystal Data. Crystal Structure Database for Inorganic Compounds, Release 2019/2020, ASM International, Materials Park, Ohio, USA]. Only the compounds with hydroborate as the only type of anion are reviewed, although including compounds gathering more than one different hydroborate (mixed anion). Carbaborane anions and partly halogenated hydroborates are included. Hydroborates containing anions other than hydroborate or neutral molecules such as NH3 are not discussed. The coordination polyhedra around the cations, including complex cations, and the hydroborate anions are determined and constitute the basis of the structural systematics underlying hydroborates chemistry in various variants of anionic packing. The latter is determined from anion–anion coordination with the help of topology analysis using the program TOPOS [Blatov (2006), IUCr CompComm. Newsl. 7, 4–38]. The Pauling rules for ionic crystals apply only to smaller cations with the observed coordination number within 2–4. For bigger cations, the predictive power of the first Pauling rule is very poor. All non-molecular hydroborate crystal structures can be derived by simple deformation of the close-packed anionic lattices, i.e., cubic close packing (ccp) and hexagonal close packing (hcp), or body-centered cubic (bcc), by filling tetrahedral or octahedral sites. This review on the crystal chemistry of hydroborates is a contribution that should serve as a roadmap for materials engineers to design new materials, synthetic chemists in their search for promising compounds to be prepared, and materials scientists in understanding the properties of novel materials.

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Rashid, Ambreen, Sahidul Mondal, and Pradyut Ghosh. "Development and Application of Ruthenium(II) and Iridium(III) Based Complexes for Anion Sensing." Molecules 28, no. 3 (January 27, 2023): 1231. http://dx.doi.org/10.3390/molecules28031231.

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Improvements in the design of receptors for the detection and quantification of anions are desirable and ongoing in the field of anion chemistry, and remarkable progress has been made in this direction. In this regard, the development of luminescent chemosensors for sensing anions is an imperative and demanding sub-area in supramolecular chemistry. This decade, in particular, witnessed advancements in chemosensors based on ruthenium and iridium complexes for anion sensing by virtue of their modular synthesis and rich chemical and photophysical properties, such as visible excitation wavelength, high quantum efficiency, high luminescence intensity, long lifetimes of phosphorescence, and large Stokes shifts, etc. Thus, this review aims to summarize the recent advances in the development of ruthenium(II) and iridium(III)-based complexes for their application as luminescent chemosensors for anion sensing. In addition, the focus was devoted to designing aspects of polypyridyl complexes of these two transition metals with different recognition motifs, which upon interacting with different inorganic anions, produces desirable quantifiable outputs.

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Helal, Aasif, Mohd Yusuf Khan, Abuzar Khan, Muhammad Usman, and Md Hasan Zahir. "Reticular Chemistry for Optical Sensing of Anions." International Journal of Molecular Sciences 24, no. 17 (August 22, 2023): 13045. http://dx.doi.org/10.3390/ijms241713045.

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In the last few decades, reticular chemistry has grown significantly as a field of porous crystalline molecular materials. Scientists have attempted to create the ideal platform for analyzing distinct anions based on optical sensing techniques (chromogenic and fluorogenic) by assembling different metal-containing units with suitable organic linking molecules and different organic molecules to produce crystalline porous materials. This study presents novel platforms for anion recognition based on reticular chemistry with high selectivity, sensitivity, electronic tunability, structural recognition, strong emission, and thermal and chemical stability. The key materials for reticular chemistry, Metal-Organic Frameworks (MOFs), Zeolitic Imidazolate Frameworks (ZIFs), and Covalent-Organic Frameworks (COFs), and the pre- and post-synthetic modification of the linkers and the metal oxide clusters for the selective detection of the anions, have been discussed. The mechanisms involved in sensing are also discussed.

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Basappa, Suma, Ramesh Bhawar, D. H. Nagaraju, and Shubhankar Kumar Bose. "Recent advances in the chemistry of the phosphaethynolate and arsaethynolate anions." Dalton Transactions 51, no. 10 (2022): 3778–806. http://dx.doi.org/10.1039/d1dt03994f.

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Davis, Jeffery T., Philip A. Gale, and Roberto Quesada. "Advances in anion transport and supramolecular medicinal chemistry." Chemical Society Reviews 49, no. 16 (2020): 6056–86. http://dx.doi.org/10.1039/c9cs00662a.

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The development of discrete molecular carriers for anions and supramolecular anion channels are reviewed followed by an overview of the use of these systems in biological systems as putative treatments for diseases such as cystic fibrosis and cancer.

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6

Flood, Amar H. "Creating molecular macrocycles for anion recognition." Beilstein Journal of Organic Chemistry 12 (March 31, 2016): 611–27. http://dx.doi.org/10.3762/bjoc.12.60.

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The creation and functionality of new classes of macrocycles that are shape persistent and can bind anions is described. The genesis of triazolophane macrocycles emerges out of activity surrounding 1,2,3-triazoles made using click chemistry; and the same triazoles are responsible for anion capture. Mistakes made and lessons learnt in anion recognition provide deeper understanding that, together with theory, now provides for computer-aided receptor design. The lessons are acted upon in the creation of two new macrocycles. First, cyanostars are larger and like to capture large anions. Second is tricarb, which also favors large anions but shows a propensity to self-assemble in an orderly and stable manner, laying a foundation for future designs of hierarchical nanostructures.

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7

Dye, J. L. "CHEMISTRY: Electrons as Anions." Science 301, no. 5633 (August 1, 2003): 607–8. http://dx.doi.org/10.1126/science.1088103.

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8

Zhu, Xiaotian, Chang Liu, and Jie Liu. "Colorimetric Detection of Sulfide Anions via Redox-Modulated Surface Chemistry and Morphology of Au-Hg Nanorods." International Journal of Analytical Chemistry 2019 (May 2, 2019): 1–9. http://dx.doi.org/10.1155/2019/8961837.

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A new colorimetric assay for the detection of sulfide anions with high sensitivity and selectivity is reported, utilizing Au-Hg alloy nanorods (Au-HgNRs) as probe. Au-HgNRs were prepared by modifying gold nanorods (AuNRs) with reducing agent and mercury ions. In an aqueous solution with sulfide anions, the formation of mercuric sulfide due to redox reaction between the amalgams and sulfide anions greatly changed the surface chemistry and morphology of the Au-HgNRs, leading to a red shift of the localized surface plasmon resonance (LSPR) absorption peak, accompanied by a change in colorimetric response. A good linear relationship was obtained between the LSPR peak wavelength shift and concentration of sulfide anion in the range of 1 × 10−5−1 × 10−4 mol/L. The selectivity of this method has been investigated by other anions. The colorimetric sensing system successfully detected sulfide in wastewater from leather industry.

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9

Černý, Radovan, and Pascal Schouwink. "The crystal chemistry of inorganic metal borohydrides and their relation to metal oxides." Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 71, no. 6 (December 1, 2015): 619–40. http://dx.doi.org/10.1107/s2052520615018508.

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The crystal structures of inorganic homoleptic metal borohydrides are analysed with respect to their structural prototypes found amongst metal oxides in the inorganic databases such as Pearson's Crystal Data [Villars & Cenzual (2015). Pearson's Crystal Data. Crystal Structure Database for Inorganic Compounds, Release 2014/2015, ASM International, Materials Park, Ohio, USA]. The coordination polyhedra around the cations and the borohydride anion are determined, and constitute the basis of the structural systematics underlying metal borohydride chemistry in various frameworks and variants of ionic packing, including complex anions and the packing of neutral molecules in the crystal. Underlying nets are determined by topology analysis using the program TOPOS [Blatov (2006). IUCr CompComm. Newsl. 7, 4–38]. It is found that the Pauling rules for ionic crystals apply to all non-molecular borohydride crystal structures, and that the latter can often be derived by simple deformation of the close-packed anionic lattices c.c.p. and h.c.p., by partially removing anions and filling tetrahedral or octahedral sites. The deviation from an ideal close packing is facilitated in metal borohydrides with respect to the oxide due to geometrical and electronic considerations of the BH4 − anion (tetrahedral shape, polarizability). This review on crystal chemistry of borohydrides and their similarity to oxides is a contribution which should serve materials engineers as a roadmap to design new materials, synthetic chemists in their search for promising compounds to be prepared, and materials scientists in understanding the properties of novel materials.

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10

Jolliffe, Katrina (Kate) A., and Philip A. Gale. "The supramolecular chemistry of anions." Organic & Biomolecular Chemistry 20, no. 4 (2022): 713–14. http://dx.doi.org/10.1039/d1ob90183d.

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11

Setifi, Fatima, David K. Geiger, Ibrahim Abdul Razak, and Zouaoui Setifi. "Multiple N—H...NC, C—H...NC and nitrile...π interactions in 4,4′-bipyridine-1,1′-diium bis(1,1,3,3-tetracyano-2-ethoxypropenide): structure determination and DFT calculations of anion...π cation interaction energies." Acta Crystallographica Section C Structural Chemistry 71, no. 8 (July 7, 2015): 658–63. http://dx.doi.org/10.1107/s2053229615012437.

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Polynitrile anions are important in both coordination chemistry and molecular materials chemistry, and are interesting for their extensive electronic delocalization. The title compound crystallizes with two symmetry-independent half 4,4′-bipyridine-1,1′-diium (bpyH22+) cations and two symmetry-independent 1,1,3,3-tetracyano-2-ethoxypropenide (tcnoet−) anions in the asymmetric unit. One of the bpyH22+ions is located on a crystallographic twofold rotation axis (canted pyridine rings) and the other is located on a crystallographic inversion center (coplanar pyridine rings). The ethyl group of one of the tcnoet−anions is disordered over two sites with equal populations. The extended structure exhibits two separate N—H...NC hydrogen-bonding motifs, which result in a sheet structure parallel to (010), and weak C—H...NC hydrogen bonds form joined rings. Two types of multicenter CN...π interactions are observed between the bpyH22+rings and tcnoet−anions. An additonal CN...π interaction between adjacent tcnoet−anions is observed. Using density functional theory, the calculated attractive energy between cation and anion pairs in the tcnoet−...π(bipyridinediium) interactions were found to be 557 and 612 kJ mol−1for coplanar and canted bpyH22+cations, respectively.

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12

Wade, Casey R., and François P. Gabbaï. "Cyanide and Azide Anion Complexation by a Bidentate Stibonium-Borane Lewis Acid." Zeitschrift für Naturforschung B 69, no. 11-12 (December 1, 2014): 1199–205. http://dx.doi.org/10.5560/znb.2014-4168.

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Abstract Our ongoing interest in the chemistry of polyfunctional Lewis acids has led us to investigate the reaction of the stibonium-borane [o-(Ph2MeSb)(Mes2B)C6H4]+ (1+) with cyanide and azide, two toxic anions. Both anions react with 1+ to afford the corresponding neutral complexes 1-CN and 1-N3. Structural and computational studies show that the coordinated anion interacts with both the boron and antimony atoms of the bidentate Lewis acid. While the azide complex features a typical κ2N1 : N1 bridging azide ligand, the cyanide complex possesses a cyanoborate moiety whose cyanide interacts side-on with the stibonium center. The Lewis acid-anion interactions observed in these complexes have also been studied computationally using the Natural Bond Orbital method

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13

Müscher-Polzin, Philipp, Christian Näther, and Wolfgang Bensch. "Hexaniobate anions connected by [Ni(cyclam)]2+ complexes yield two interpenetrating three-dimensional networks." Zeitschrift für Naturforschung B 75, no. 6-7 (August 27, 2020): 583–88. http://dx.doi.org/10.1515/znb-2020-0043.

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AbstractSyntheses were performed at room temperature using Ni(NO3)2·6H2O, cyclam (cyclam = 1,4,8,11-tetraazacyclotetradecane) and the precursors Li8[Nb6O19]· ≈22H2O or Na7[HNb6O19]·15H2O in a DMSO-H2O mixture. Yellow crystals of the new compound {[Ni(cyclam)]2H4Nb6O19}·12H2O could be obtained after one week applying the Li+ or Na+ salt as starting materials. The crystal structure is unique in polyoxoniobate (PONb) chemistry and displays two interpenetrating three-dimensional (3D) networks. The [Nb6O19]8– anion is expanded by four Ni2+ centered complexes via Ni–O bonds to terminal O2− anions of the hexaniobate anion. The 3D networks are generated by further Ni–O bond formation between neighboring [Nb6O19]8− anions. The remaining void space is occupied by H2O molecules which form a water cluster.

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14

Li, Chongyang, Yongli Huang, Chang Q. Sun, and Lei Zhang. "Acidic Stabilization of the Dual-Aromatic Heterocyclic Anions." Catalysts 11, no. 7 (June 24, 2021): 766. http://dx.doi.org/10.3390/catal11070766.

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Recently, we discovered that the delocalization of nitrogen lone-pair electrons (NLPEs) in five-membered nitrogen heterocycles created a second σ-aromaticity in addition to the prototypical π-aromaticity. Such dual-aromatic compounds, such as the pentazole anion, were proved to have distinct chemistry in comparison to traditional π-aromatics, such as benzene, and were surprisingly unstable, susceptible to electrophilic attack, and relatively difficult to obtain. The dual-aromatics are basic in nature, but prefer not to be protonated when confronting more than three hydronium/ammonium ions, which violates common sense understanding of acid−base neutralization for a reason that is unclear. Here, we carried out 63 test simulations to explore the stability and reactivity of three basic heterocycle anions (pentazole anion N5¯, tetrazole anion N4C1H1¯, and 1,2,4-triazole anion N3C2H2¯) in four types of solvents (acidic ions, H3O+ and NH4+, polar organics, THF, and neutral organics, benzene) with different acidities and concentrations. By quantum mechanical calculations of the electron density, atomistic structure, interatomic interactions, molecular orbital, magnetic shielding, and energetics, we confirmed the presence of dual aromaticity in the heterocyclic anions, and discovered their reactivity to be a competition between their basicity and dual aromaticity. Interestingly, when the acidic ions H3O+/NH4+ are three times more in number than the basic heterocyclic anions, the anions turn to violate acid−base neutralization and remain unprotonated, and the surrounding acidic ions start to show a significant stabilization effect on the studied heterocyclic anions. This work brings new knowledge to nitrogen aromatics and the finding is expected to be adaptable for other pnictogen five-membered ring systems.

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15

Durkin, Kathleen Anne, Richard Francis Langler, and Nancy Ann Morrison. "Sulfonyl esters 1: The reduction of tribromophenyl sulfonates with mercaptide anions." Canadian Journal of Chemistry 66, no. 12 (December 1, 1988): 3070–76. http://dx.doi.org/10.1139/v88-475.

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2,4,6-Tribromophenyl sulfonates have been shown to undergo unusually efficient reduction by mercaptide anions in hexamethylphosphoramide. The reduction products include the sulfinate anion derived from the sulfonate ester and the disulfide derived from the mercaptide anions.

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Joseph, Stefanie, Christof Suchentrunk, and Nikolaus Korber. "Dissolving Silicides: Syntheses and Crystal Structures of New Ammoniates Containing Si52– and Si94– Polyanions and the Role of Ammonia of Crystallisation." Zeitschrift für Naturforschung B 65, no. 9 (September 1, 2010): 1059–65. http://dx.doi.org/10.1515/znb-2010-0901.

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The dissolution of the ternary material K6Rb6Si17 in liquid ammonia yields the solvate compound Rb4Si9 ・ 5NH3, which contains fourfold negatively charged nine atom silicon clusters Si94−. Using additionally the [2.2.2] cryptand during the dissolution results in the solvate [K(2.2.2- crypt)]2Si5 ・ 4NH3 , in which the Si52− anion is present in the crystal structure. The Si52− anion has the shape of a nearly ideal trigonal bipyramid. The starting material K6Rb6Si17 contains both Si44− and Si94− Zintl anions. In ammoniate crystal structures, Si94− anions are accessible independently of Si44− anions, and ammonia of crystallisation plays a major role in the observed crystal symmetry. For the cryptate structures of Si52− and Ge52− anions ammonia of crystallisation is obligatory despite the loss of crystal symmetry compared to the crystal structures of the heavier homologues Pb52− and Sn52−.

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Haider, Azeem, Mukhtiar Ahmed, Muhammad Faisal, and Muhammad Moazzam Naseer. "Isatin as a simple, highly selective and sensitive colorimetric sensor for fluoride anion." Heterocyclic Communications 26, no. 1 (March 17, 2020): 14–19. http://dx.doi.org/10.1515/hc-2020-0003.

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AbstractHerein, we report the fluoride anion sensing properties of a commercially available and inexpensive organic compound, isatin, which is found to be a highly selective and sensitive sensor. In naked-eye experiments, by addition of fluoride anions, isatin shows a dramatic color change from pale yellow to violet at room temperature, while the addition of other anions, i.e. $\mathrm{Cl}^-,$$\mathrm{Br}^-,\mathrm I^-,\mathrm{ClO}_4^-,{\mathrm H}_2\mathrm{PO}_4^-\,\mathrm{and}\,\mathrm{PF}_6^-,$did not induce any colour change. Additionally, recognition and titration studies have also been done through UV/Vis spectroscopy. Isatin displayed a new absorption band at 533 nm after the addition of fluoride anions, which is presumably due to acid-base interaction between isatin and fluoride anions, while other anions did not trigger noticeable spectral changes. The detection limit was observed to be 0.367 ppm. DFT calculations were also performed to further explain the behavior of receptor 1 towards the Fˉ anion. Owing to high sensitivity and selectivity, isatin can be useful in the detection of biologically or environmentally important fluoride anions at very low concentration.

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Bowes, Katharine F., George Ferguson, Alan J. Lough, and Christopher Glidewell. "Phosphonopropionic acid as a building block in supramolecular chemistry: salts with organic diamines." Acta Crystallographica Section B Structural Science 59, no. 2 (March 26, 2003): 248–62. http://dx.doi.org/10.1107/s0108768102021237.

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The structures of seven salts formed by phosphonopropionic acid with organic diamines are reported; in these salts, the hydrogen-bonded substructures formed by the anions can be zero-, one- or two-dimensional, while the overall hydrogen-bonded supramolecular structures are three-dimensional. The 1:1 adduct, compound (1), formed between 1,2-bis(4′-pyridyl)ethene and phosphonopropionic acid is a salt, [{(C12H10N2)H2}2+]·[(C12H10N2)]·[(C3H6O5P)−]2, in which both diamine components lie across centres of inversion in space group P21/c. The anions form hydrogen-bonded head-to-head dimers, and these are linked by the two diamine units into sheets, which are themselves linked by C—H...O hydrogen bonds. With 2,2′-dipyridylamine the acid forms the hydrated salt [{(C10H9N3)H}+]·[(C3H6O5P)−]·H2O (2), in which all components are disordered with occupancy 0.5 in space group Fmm2. The anions form head-to-tail dimers, which are linked into sheets by the cations, and the sheets are linked into a three-dimensional framework by the water molecules. The piperazine salt [{(C4H10N2)H2}2+]·[(C3H5O5P)2−] (3) contains simple anion chains linked into a three-dimensional framework by the two independent cations, both of which are centrosymmetric. In the hydrated salt formed by N,N′-dimethylpiperazine, [{(MeNC4H8NMe)H2}2+]·[(C3H6O5P)−]2·(H2O)2 (4), head-to-tail anion chains combine with the water molecules to form a three-dimensional framework, which encloses voids that contain the cations. In the 4,4′-bipyridyl adduct [{(C10H8N2)H0.72}0.72+]·[{(H0.5O)3PCH2CH2COOH0.78}0.72−] (5), there is extensive disorder of the H atoms that are bonded to N and O atoms, and the anion chains are linked by the cations into sheets, which are themselves linked by C—H...O hydrogen bonds. In the 1:2 adduct formed with 1,2-bis(4′-pyridyl)ethane, [{(C12H12N2)H2}2+]·[(C3H6O5P)−]2 (6), where the cation lies across an inversion centre, the anions form molecular ladders. These ladders are linked into sheets by the cations, which are themselves linked by C—H...O hydrogen bonds. In the methanol-solvated salt formed with 2,6-dimethylpiperazine, [{(C6H14N2)H2}2+]·[(C3H6O5P)−]2· (CH4O)0.34 (7), the anions form sheets that are linked into a three-dimensional framework by the cations. The supramolecular structures are compared with those of analogous salts formed by phosphonoacetic acid.

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19

Horton, J. Hugh, and John M. Goodings. "Silicon cation and anion chemistry in a fuel-rich, methane–oxygen flame." Canadian Journal of Chemistry 70, no. 4 (April 1, 1992): 1069–81. http://dx.doi.org/10.1139/v92-141.

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Silicon cations and anions in a fuel-rich, premixed, methane–oxygen flame at atmospheric pressure doped with 0.01 mol% of trimethylsilane were observed by sampling the flame through a nozzle into a mass spectrometer. Twelve cations were observed which can be grouped into five series: SiOH+.nH2O (n = 0–2); SiOCH3+.nH2O (n = 0–2); Si(OH)3+.nH2O (n = 0–2); cations by nucleophilic substitution (e.g., Si(OH)(CH3)2(H2O)+); and carbonaceous aromatic cations (c-HSiCH=CH+ and c-HSiCH=CCH3+). Similarly, five anions were observed as members of two series: HxSiO3− (x = 0, 1) and HxSiO4− (x = 1–3). The chemical ionization reactions for the formation of these ions are discussed in detail, including proton transfer and also methyl cation transfer, three-body addition, nucleophilic substitution (SN2) of both the ions themselves and also their neutral silicon precursors, and H-atom abstraction reactions. The neutral silicon chemistry in the flame is dominated by SiO, but evidence was obtained from both the cation and the anion chemistry for the presence of HSiO(OH), silanoic acid; SiO(OH)2, metasilicic acid; and Si(OH)4, orthosilicic acid. The silicon ion chemistry differs markedly from the normal carbon ion chemistry that occurs naturally in the undoped methane–oxygen flame; the silicon ions show a strong tendency towards Si—O bond formation. Consideration is given to the probable structures of the various silicon cations and anions observed.

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Tepuš, Brigita, and Marjana Simonič. "Uncertainty of nitrate and sulphate measured by ion chromatography in wastewater samples." Open Chemistry 5, no. 2 (June 1, 2007): 557–69. http://dx.doi.org/10.2478/s11532-007-0002-3.

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AbstractThis paper presents an evaluation of measurement uncertainty regarding the results of anion (nitrate and sulphate) concentrations in wastewater. Anions were determined by ion chromatography (EN ISO 10304-2, 1996). The major sources of uncertainty regarding the measurements’ results were identified as contributions to linear least — square or weighted regression lines, precision, trueness, storage conditions, and sampling. Determination of anions in wastewater is very important for the purification procedure, especially the amount of nitrate in waste and potable waters. The determined expanded uncertainty was 6.1 % for nitrate anions and 8.3 % for sulphate anions. The difference between measurement uncertainties determined by the two methods, the weighted and linear least — square methods, is negligible.

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Ren, Xiaoming, and Peter G. Pickup. "Ion–polymer interactions in polypyrrole films." Canadian Journal of Chemistry 75, no. 11 (November 1, 1997): 1518–22. http://dx.doi.org/10.1139/v97-182.

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Formal potentials from cyclic voltammetry and ionic conductivities from impedance measurements are used to probe anion–polymer interactions in electrochemically deposited films of polypyrrole. Hard anions (F−, Cl−, ClO4−) stabilize the oxidized form of the polymer more than soft anions (I−, SCN−). Anions of weak acids (F− and CN−) interact with the polymer particularly strongly and exhibit anomalously low mobilities. Hydrogen bonding with the N-H groups of oxidized polypyrrole is proposed. Keywords: conducting polymer, polypyrrole, impedance, ion transport, electrolyte effects, ion exchange.

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Bull, James N., Christopher W. West, and Jan R. R. Verlet. "On the formation of anions: frequency-, angle-, and time-resolved photoelectron imaging of the menadione radical anion." Chemical Science 6, no. 2 (2015): 1578–89. http://dx.doi.org/10.1039/c4sc03491k.

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Frequency-, angle-, and time-resolved photoelectron imaging of gas-phase menadione (vitamin K₃) radical anions is used to show that quasi-bound resonances of the anion can act as efficient doorway states to produce metastable ground electronic state anions on a sub-picosecond timescale.

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Yuan, Dan, and Yuan Fang Li. "Carboxyphenyl-terpyridine-based series of gels for procedural visual recognition of multi-anions." Analytical Methods 10, no. 41 (2018): 5032–37. http://dx.doi.org/10.1039/c8ay01679h.

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The gelation of 4-[2,2′:6′,2′′-terpyridine]-4′-ylbenzoic acid (Hcptpy) occurred with various metal ions and specific anions. With the gel formation, corresponding metal ions and anions were recognized. Also, the metal–organic gels (MOGs) possess stimuli response property to anions. A step-by-step anion recognition progress was established based on one Hcptpy ligand and realized the selective identification 12 kinds of anions.

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Krivovichev, S. V., R. Turner, M. RumseY, O. I. Siidra, and C. A. Kirk. "The crystal structure and chemistry of mereheadite." Mineralogical Magazine 73, no. 1 (February 2009): 103–17. http://dx.doi.org/10.1180/minmag.2009.073.1.103.

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The crystal structure of mereheadite (monoclinic, Cm, a = 17.372(1), b = 27.9419(19), c = 10.6661(6) Å, β = 93.152(5)°, V = 5169.6(5) Å3) has been solved by direct methods and refined to R1 = 0.058 for 6279 unique observed reflections. The structure consists of alternating Pb–O/OH blocks and Pb–Cl sheets oriented parallel toth e (201) plane and belongs toth e 1:1 type of lead oxide halides with PbO blocks. It contains 30 symmetrically independent Pb positions, 28 of which belong to the PbO blocks, whilst two positions (Pb12 and Pb16) are located within the tetragonal sheets of the Cl– anions. Mereheadite is thus the first naturally occurring lead oxychloride mineral with inter-layer Pb ions. The coordination configurations of the Pb atoms of the PbO blocks are distorted versions of the square antiprism. In one half of the coordination hemisphere, they are coordinated by hard O2– and OH– anions whose number varies from three to four, whereas the other coordination hemisphere invariably consists of four soft Cl– anions located at the vertices of a distorted square. The Pb12 and Pb16 atoms in between the PbO blocks have an almost planar square coordination of four Cl– anions. These PbCl4 squares are complemented by triangular TO3 groups (T = B, C) so that a sevenfold coordination is achieved. The Pb–O/OH block in mereheadite can be obtained from the ideal PbO block by the following list of procedures: (1) removal of some PbO4 groups that results in the formation of square-shaped vacancies; (2) insertion of TO3 groups into these vacancies; (3) removal of some Pb atoms (that correspond to the Pb1A and Pb2A sites), thus transforming coordination of associated O sites from tetrahedral OPb4 tot riangular OHPb3; and (4) replacement of two O2– anions by one OH– anion with twofold coordination; this results in formation of the 1×2 elongated rectangular vacancy. The structural formula that can be derived on the basis of the results of single-crystal structure determination is Pb47O24(OH)13Cl25(BO3)2(CO3). Welch et al. (1998) proposed the formula Pb2O(OH)Cl for mereheadite, which assumes that neither borate nor carbonate is an essential constituent of mereheadite and their presence in the mineral is due to disordered replacements of Cl– anions. However, our study demonstrates that this is not the case, as BO3 and CO3 groups have well-defined structural positions confined in the vacancies of the Pb–O/OH blocks and are therefore essential constituents. Our results also show that mereheadite is not a polymorph of blixite, but is in fact related to symesite. Symesite thus becomes the baseline member of a group of structurallyrelated minerals.

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Li, Lei, Yu-Jian Hong, Dong-Yang Chen, Wang-Chuan Xiao, and Mei-Jin Lin. "Anion–π interactions in lithium–organic redox flow batteries." Chemical Communications 55, no. 16 (2019): 2364–67. http://dx.doi.org/10.1039/c8cc09834d.

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The interactions between the electrolyte anions and electron-deficient redox-active organic molecules (anion–π interactions) have strong influences on the battery properties due to the anion–π-induced formation of radical anions or sandwich-like aggregates.

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26

Kauzlarich, Susan M. "Special Issue: Advances in Zintl Phases." Materials 12, no. 16 (August 11, 2019): 2554. http://dx.doi.org/10.3390/ma12162554.

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Zintl phases have garnered a great deal of attention for many applications. The term “Zintl phase” recognizes the contributions of the German chemist Eduard Zintl to the field of solid-state chemistry. While Zintl phases were initially defined as a subgroup of intermetallic phases where cations and anions or polyanions in complex intermetallic structures are valence satisfied, the foundational idea of electron counting to understand complex solid-state structures has provided insight into bonding and a bridge between solid-state and molecular chemists. This Special Issue, “Advances in Zintl Phases”, provides a collage of research in the area, from solution to solid-state chemistry.

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27

Nicholas, A. Martin de P., and Roderick E. Wasylishen. "Rotations of linear triatomic anions in aqueous solution by nuclear magnetic resonance spectroscopy." Canadian Journal of Chemistry 64, no. 9 (September 1, 1986): 1839–44. http://dx.doi.org/10.1139/v86-302.

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The temperature dependence of nitrogen-14 nuclear magnetic resonance (nmr) spin-lattice relaxation times (T1) for dilute aqueous solutions of the linear triatomic anions, SeCN−, SCN−, OCN−, and N3−, is investigated in the temperature range 3–80 °C. These nmr relaxation times (T1) yield rotational correlation times, τ2R, for the reorientation of the C∞ symmetry axis in these anions. The observed nonlinear dependence of log T1(14N) on temperature suggests that the rotations of the anions are coupled to the transport properties of water. For the thiocyanate anion the nmr correlation times are compared with those obtained previously from Raman spectroscopic data and Rayleigh scattering results. 17O T2 and I4N T1measurements for the NCO− anion are used along with abinitio calculations to estimate the 17O nuclear quadrupolar coupling constant in this ion.

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28

Zaleskaya, Marta, Łukasz Dobrzycki, and Jan Romański. "Highly Efficient, Tripodal Ion-Pair Receptors for Switching Selectivity between Acetates and Sulfates Using Solid–Liquid and Liquid–Liquid Extractions." International Journal of Molecular Sciences 21, no. 24 (December 12, 2020): 9465. http://dx.doi.org/10.3390/ijms21249465.

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A tripodal, squaramide-based ion-pair receptor 1 was synthesized in a modular fashion, and 1H NMR and UV-vis studies revealed its ability to interact more efficiently with anions with the assistance of cations. The reference tripodal anion receptor 2, lacking a crown ether unit, was found to lose the enhancement in anion binding induced by presence of cations. Besides the ability to bind anions in enhanced manner by the “single armed” ion-pair receptor 3, the lack of multiple and prearranged binding sites resulted in its much lower affinity towards anions than in the case of tripodal receptors. Unlike with receptors 2 or 3, the high affinity of 1 towards salts opens up the possibility of extracting extremely hydrophilic sulfate anions from aqueous to organic phase. The disparity in receptor 1 binding modes towards monovalent anions and divalent sulfates assures its selectivity towards sulfates over other lipophilic salts upon liquid–liquid extraction (LLE) and enables the Hofmeister bias to be overcome. By changing the extraction conditions from LLE to SLE (solid–liquid extraction), a switch of selectivity from sulfates to acetates was achieved. X-ray measurements support the ability of anion binding by cooperation of the arms of receptor 1 together with simultaneous binding of cations.

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29

Kotyńska, Joanna, and Monika Naumowicz. "Theoretical Considerations and the Microelectrophoresis Experiment on the Influence of Selected Chaotropic Anions on Phosphatidylcholine Membrane Surface Charge Density." Molecules 25, no. 1 (December 29, 2019): 132. http://dx.doi.org/10.3390/molecules25010132.

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Influence of sodium salts of selected chaotropic anions from the Hofmeister series (NaCl, NaBr, NaNO3, NaI) on the surface charge density of phosphatidylcholine membranes was studied. Small unilamellar lipid vesicles were used as a model system in the investigations. The theoretical and experimental approach to the interactions between inorganic anions and phosphatidylcholine membranes is presented. Experimental membrane surface charge densities data were determined as a function of pH of the aqueous electrolytes using microelectrophoresis method. The quantitative description of the interactions between zwitterionic phosphatidylcholine membrane and monovalent anions is presented. The equilibria constants of the binding of solution ions onto phospholipid surface were calculated. Knowledge of these parameters was essential to determine the theoretical membrane surface charge density values. The theoretical data were compared to the experimental ones in order to verify the mathematical model. Both approaches indicate that the anion-phosphatidylcholine membrane interaction increases with the size of the anion. The adsorption of chaotropic anions to membranes was found to follow the Hofmeister series I− > NO3− > Br− > Cl−.

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30

Parlow, Axel, and Hans Hartl. "Synthese und Strukturuntersuchung von Polyhalogeniden im System Iod/Brom / Syntheses and Structure Analyses of Polyhalides in the System Iodine/Bromine." Zeitschrift für Naturforschung B 40, no. 1 (January 1, 1985): 45–52. http://dx.doi.org/10.1515/znb-1985-0111.

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Several polyhalide anions containing iodine and bromine have been synthesized with 2,2′- bipyridylium (BPH+) as the cation. The crystal structures of three compounds have been investigated by X-ray crystal structure analyses. BPH+(H3O)+(IBr2)2- (P1̄, a = 780.0(3), b = 815.4(3), c = 1547.9(6) pm, α = 75.59(7), β = 82.28(8), γ = 88.15(8)°, R = 6.5%) contains two independent, nearly linear, asymmetric IBr2- groups. In BPH+I2Br3- (P21/c, a = 1269.1(6), b = 673.0(4), c = 2047.4(8) pm, β = 112.39(9)°, R = 6.3%), the anion is V-shaped like other pentahalide anions. It can be characterized as consisting of two IBr molecules linked to a bromide anion with the longer I-Br bonds at the central atom. The polyhalide anions in [xxx] (P21/m, a = 435.1(2), b = 1710.6(7), c = 1349.0(6) pm, β = 97.56(9)°, R = 15.5%) form infinite zigzag layers. They are built up by IBr2- anions which are connected by iodine molecules. The cations are enclosed in columnar cavities within these layers

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31

Denmark, Scott E., and Jung-Ho Kim. "Diastereoselective alkylations of chiral, phosphorus-stabilized carbanions: N-alkyl substituent effects in P-alkyl-1,3,2-diazaphosphorinane 2-oxides." Canadian Journal of Chemistry 78, no. 6 (June 1, 2000): 673–88. http://dx.doi.org/10.1139/v99-251.

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A systematic study of the diastereoselective alkylation of anions derived from racemic N-substituted P-alkyl 1,3,2-diazaphosphorinane 2-oxides was carried out with variation of the N-substituent. High diastereoselectivity for the methylation of a P-benzyl anion has been achieved with N-neopentyl derivative 5d. Similarly, a P-ethyl anion derived from N-neopentyl derivative 6d showed high diastereoselectivity upon benzylation. The observed difference in alkylation diastereoselectivity between P-ethyl and P-benzyl anions for various N-alkyl substituents is discussed.Key words: phosphonamide-stabilized carbanions, alkylation, asymmetric, stereoselective, organolitihium.

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32

Tisovský, Pavol, Miroslav Horváth, Klaudia Csicsai, Jana Donovalová, Juraj Filo, Marek Cigáň, Róbert Sokolík, Gabriela Addová, and Anton Gáplovský. "Isatin-1,8-Naphthalimide Hydrazones: A Study of Their Sensor and ON/OFF Functionality." Molecules 24, no. 3 (January 22, 2019): 397. http://dx.doi.org/10.3390/molecules24030397.

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Five novel hydrazones derived from substituted isatins were synthesized as potential anion sensors. Using UV-VIS, FTIR, NMR and fluorescence spectroscopy, these compounds’ tautomeric equilibrium and Z-E photoisomerization were studied in DMF and CHCl3, depending on the hydrazone concentrations, the presence of basic anions and light stimulation. Anion recognition aspects (PF6−, HSO4−, Br−, Cl−, NO3−, F− and CH3COO−) and these receptors’ detection limits were also studied. We also tested the light-stimulated ON-OFF functionality of these compounds in the presence or absence of these anions.

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33

Maslowska-Jarzyna, Krystyna, Maria L. Korczak, Jakub A. Wagner, and Michał J. Chmielewski. "Carbazole-Based Colorimetric Anion Sensors." Molecules 26, no. 11 (May 27, 2021): 3205. http://dx.doi.org/10.3390/molecules26113205.

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Owing to their strong carbazole chromophore and fluorophore, as well as to their powerful and convergent hydrogen bond donors, 1,8-diaminocarbazoles are amongst the most attractive and synthetically versatile building blocks for the construction of anion receptors, sensors, and transporters. Aiming to develop carbazole-based colorimetric anion sensors, herein we describe the synthesis of 1,8-diaminocarbazoles substituted with strongly electron-withdrawing substituents, i.e., 3,6-dicyano and 3,6-dinitro. Both of these precursors were subsequently converted into model diamide receptors. Anion binding studies revealed that the new receptors exhibited significantly enhanced anion affinities, but also significantly increased acidities. We also found that rear substitution of 1,8-diamidocarbazole with two nitro groups shifted its absorption spectrum into the visible region and converted the receptor into a colorimetric anion sensor. The new sensor displayed vivid color and fluorescence changes upon addition of basic anions in wet dimethyl sulfoxide, but it was poorly selective; because of its enhanced acidity, the dominant receptor-anion interaction for most anions was proton transfer and, accordingly, similar changes in color were observed for all basic anions. The highly acidic and strongly binding receptors developed in this study may be applicable in organocatalysis or in pH-switchable anion transport through lipophilic membranes.

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34

Xu, Si-Yu, Zhou-Yu Meng, Feng-Qi Zhao, and Xue-Hai Ju. "Density functional study of guanidine-azole salts as energetic materials." Canadian Journal of Chemistry 96, no. 10 (October 2018): 949–56. http://dx.doi.org/10.1139/cjc-2018-0106.

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A series of guanidine cations and azole anions were designed for use as energetic salts. Their geometrical structures were optimized by the density functional theory (DFT) method. The counter ions were matched by the similar magnitude of the electron affinity (EA) of the cation and the ionization potential (IP) of the anion. The densities, heats of formation, detonation parameters, and impact sensitivity were predicted. The incorporation of guanidine cations and diazole anions are favorable to form thermal stable salts except cation A1. The diaminoguanidine cation has greater impact on the density and detonation properties of the salts than the triaminoguanidine cation. 2-Amino-3-nitroamino-4,5-nitro-dinitropyrazole is the best anion for advancing the detonation performance among all the anions. Incorporating the C=O bond into the guanidine cations enhances the density and detonation performance of the guanidine-azole salts. The salts containing III1–III4 anion have better detonation properties than HMX, indicating that these salts are potential energetic compounds. Compared with RDX or HMX, some salts with diaminoguanidine cation display lower impact sensitivity.

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35

Fitriana, Adita Silvia, Harno Dwi Pranowo, and Bambang Purwono. "Chalcone Based Colorimetric Sensor for Anions: Experimental and TD-DFT Study." Indonesian Journal of Chemistry 16, no. 1 (March 15, 2018): 80. http://dx.doi.org/10.22146/ijc.21181.

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The interactions between sensor chalcone of 3-(4-hydroxy-3-methoxyphenyl)-1-phenyl-2-propen-1-one (1) and anions (F–, Cl–, Br–, CN–, CO32–, and SO42–) have been experimentally and TD-DFT theoretically investigated. Sensor (1) showed a naked-eye detectable color change from yellow to red upon addition of F–, CO32–, CN–, and SO42– anions in DMSO, whereas no significant color change was observed upon addition of Cl– and Br– anions. The interaction models were predicted by optimizing (1)-anion complex using DFT/B3LYP method. Optimized (1)-anion complexes showed that sensor (1) was deprotonated by CO32–, CN–, F–, and SO42–. The formation of deprotonated sensor (1)– was responsible for the colorimetric signaling. Absorption spectra of neutral and deprotonated sensor were calculated using TD-DFT method. The calculated spectra were in good agreement with experimental results.

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36

Yan, Liwei, Ankur Saha, Wei Zhao, Jennifer F. Neal, Yusheng Chen, Amar H. Flood, and Heather C. Allen. "Recognition competes with hydration in anion-triggered monolayer formation of cyanostar supra-amphiphiles at aqueous interfaces." Chemical Science 13, no. 15 (2022): 4283–94. http://dx.doi.org/10.1039/d2sc00986b.

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37

GUO, JINXIN, DONGJU ZHANG, and CHENGBU LIU. "A THEORETICAL INVESTIGATION OF THE INTERACTIONS BETWEEN CELLULOSE AND 1-BUTYL-3-METHYLIMIDAZOLIUM CHLORIDE." Journal of Theoretical and Computational Chemistry 09, no. 03 (June 2010): 611–24. http://dx.doi.org/10.1142/s0219633610005906.

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To better understand the interactions between cellulose and imidazolium-based ionic liquids (ILs), quantum chemistry calculations have been performed on the systems composed of one cellulose unit with the anion, cation, and the ion pair of 1-butyl-3-methylimidazolium chloride ( [bmim]Cl ) by the density functional method. The relevant geometries, energies, electronic properties and IR characteristics have been systematically discussed. It is found that H-bond interaction is essential for the systems under consideration. The hydroxyls in cellulose bind to chloride anions strongly through H -bonds, which could be predominant to cellulose dissolution in ILs. Chloride anion prefers to occur between two adjacent hydroxyls in cellulose to form bridging OH⋯Cl⋯HO hydrogen bonds. In contrast, weak hydrogen bonds exist between the hydrogen atoms on the imidazolium cation and hydroxyl oxygen atoms of cellulose, which are too much weaker than the hydrogen bonds between the cellulose hydroxyls and chloride anions to be detected by the experiments. The phenomena of cellulose dissolution in ILs should be a result of the joint interactions of chloride anions and [bmim]+ cations with hydroxyls in cellulose.

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38

Grossholz, Hagen, Dirk D. Zimmermann, Oliver Janka, and Thomas Schleid. "Oxidfluoridsulfide der Lanthanoide vom Formeltyp M6O2F8S3 (M=La–Nd, Sm, Gd) / Oxide Fluoride Sulfides of the Lanthanoids with the Formula M6O2F8S3 (M = La–Nd, Sm, Gd)." Zeitschrift für Naturforschung B 68, no. 7 (July 1, 2013): 751–60. http://dx.doi.org/10.5560/znb.2013-3110.

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The lanthanoid(III) oxide fluoride sulfides M6O2F8S3 (M = La-Nd, Sm, Gd) can be obtained by reacting the rare-earth metals, their trifluorides and sesquioxides with elemental sulfur in appropriate molar ratios at 850 °C flux-assisted by NaCl in gas-tightly sealed niobium or tantalum ampoules. All compounds are colorless, except for those containing M = Pr with green, M = Nd with lilac and M = Sm with yellow color. They form transparent single crystals as needles or rods. The M6O2F8S3 representatives crystallize in a hexagonal structure (space group: P63/m; a≈1382 - 1326, c≈398 - 376 pm, c/a≈0:288 - 0.284; Z =2) with two different crystallographic M3+ positions. The (M2)3+ cations reside in ninefold coordination of anions arranged as tricapped trigonal prisms formed by three F-, four mixed-occupied O2-/F- and two S2- anions, resembling the unique M3+ coordination sphere of the M3OF5S-type oxide fluoride sulfides. The (M1)3+ cations are surrounded by square antiprisms built of four O2-/F- and S2- anions each, which are capped by one F- anion each, again resulting in a ninefold coordination similar to that of the A-MFS-type fluoride sulfides. While the crystallographically unique S2- anions have six cationic neighbors arranged in trigonal prisms, there are four different light-anion positions. Two of them, representing only fluoride anions, are situated in a triangular environment of cations ((F1)-: planar, (F2)-: non-planar). The mixed-occupied light-anion positions (F3)-=(O3)2- and (F4)-=(O4)2- exhibit tetrahedral coordination spheres with a ratio F- :O2- =2 : 1. The M6O2F8S3 arrangement is characterized by an empty hexagonal channel structure created by (F1)- anions with a potential of accommodating alkali-metal cations like Na+. All single-crystal X-ray structure investigations did not indicate any ordering of the O2- and F- anions, but MAPLE calculations revealed a slightly favored oxygen occupation for the (F4)-=(O4)2- rather than for the (F3)-=(O3)2- position. Electron-beam microanalyses gave no evidence for the incorporation of either Na+ or Cl- ions stemming from NaCl used as the flux.

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39

Talanov, M. V., V. B. Shirokov, and V. M. Talanov. "Anion order in perovskites: a group-theoretical analysis." Acta Crystallographica Section A Foundations and Advances 72, no. 2 (January 29, 2016): 222–35. http://dx.doi.org/10.1107/s2053273315022147.

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Anion ordering in the structure of cubic perovskite has been investigated by the group-theoretical method. The possibility of the existence of 261 ordered low-symmetry structures, each with a unique space-group symmetry, is established. These results include five binary and 14 ternary anion superstructures. The 261 idealized anion-ordered perovskite structures are considered as aristotypes, giving rise to different derivatives. The structures of these derivatives are formed by tilting ofBO6octahedra, distortions caused by the cooperative Jahn–Teller effect and other physical effects. Some derivatives of aristotypes exist as real substances, and some as virtual ones. A classification of aristotypes of anion superstructures in perovskite is proposed: theAXclass (the simultaneous ordering ofAcations and anions in cubic perovskite structure), theBXclass (the simultaneous ordering ofBcations and anions) and theXclass (the ordering of anions only in cubic perovskite structure). In most perovskites anion ordering is accompanied by cation ordering. Therefore, the main classes of anion order in perovskites are theAXandBXclasses. The calculated structures of some anion superstructures are reported. Comparison of predictions and experimentally investigated anion superstructures shows coherency of theoretical and experimental results.

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40

Martínez-Camarena, Álvaro, Matteo Savastano, Carla Bazzicalupi, Antonio Bianchi, and Enrique García-España. "Stabilisation of Exotic Tribromide (Br3−) Anions via Supramolecular Interaction with a Tosylated Macrocyclic Pyridinophane. A Serendipitous Case." Molecules 25, no. 14 (July 10, 2020): 3155. http://dx.doi.org/10.3390/molecules25143155.

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Tetraaza-macrocyclic pyridinophane L-Ts, decorated with a p-toluenesulfonyl (tosyl; Ts) group, appear to be a useful tool to provide evidence on how the interplay of various supramolecular forces can help stabilise exotic anionic species such as tribromide (Br3−) anions. Indeed, crystals of (H2L-Ts)(Br3)1.5(NO3)0.5 unexpectedly grew from an acidic (HNO3) aqueous solution of L-Ts in the presence of Br− anions. The crystal structure of this compound was determined by single crystal XRD analysis. Hydrogen bonds, salt-bridges, anion-π, π-π stacking, and van der Waals interactions contribute to stabilising the crystal lattice. The observation of two independent Br3− anions stuck over the π-electron densities of pyridine and tosyl ligand groups, one of them being sandwiched between two pyridine rings, corroborates the significance of anion-π interactions for N-containing heterocycles. We show herein the possibility of detecting anion-π contacts from fingerprint plots generated by Hirshfeld surface analysis, demonstrating the effective usage of this structural investigation technique to further dissect individual contributions of stabilising supramolecular forces.

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41

Giese, Michael, Markus Albrecht, Gergana Ivanova, Arto Valkonen, and Kari Rissanen. "Geometrically diverse anions in anion–π interactions." Supramolecular Chemistry 24, no. 1 (November 3, 2011): 48–55. http://dx.doi.org/10.1080/10610278.2011.622384.

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42

Wu, Huilu, Cuiping Wang, Jiawen Zhang, Yanhui Zhang, Chengyong Chen, Zaihui Yang, and Xuyang Fan. "1,8-Naphthalimide derivative-based turn-off fluorescent probe for the detection of picrate in organic aqueous media." Zeitschrift für Naturforschung B 70, no. 12 (December 1, 2015): 863–69. http://dx.doi.org/10.1515/znb-2015-0094.

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AbstractThe synthesis of a simple fluorescent naphthalimide-based receptor N-allyl-4-iminodi(N-butylacetamide)-1,8-naphthalimide 3 was carried out as a selective picrate (Pic–) anion probe, and the detecting behavior of this probe was studied by fluorescence spectroscopy. In DMF solution, the interaction of compound 3 with different anions, including Pic–, F–, Cl–, Br–, I–, OH–, Ac–, NO3–, ClO4–, SCN–, SO32–, SO42–, H2PO4–, and HPO42–, revealed significant fluorescence quenching only with the Pic– anion. By adding the picrate anions, green-yellow fluorescence emission quenches, which is easily observed by naked eyes under a 365 nm UV light irradiation. This phenomenon is essential for producing a highly selective and sensitive fluorescent probe for picrate anions. The probe can be applied to the quantification of Pic– with a linear range covering from 4.97 × 10–6 to 6.82 × 10–5m and a detection limit of 5.8 × 10–7m. Most importantly, probe 3 has a high selectivity for picrate over competitive anions and picrate-containing analytes, which meet the selective requirements for practical application. Thus, the present results would be inspiring findings in the future design of reaction-based fluorescent turn-off probes for the environmentally relevant picrate probe.

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43

Ji, Hailong, Fengyu Liu, and Shiguo Sun. "Study of the Counter Anions in the Host-Guest Chemistry of Cucurbit[8]uril and 1-Ethyl-1′-benzyl-4,4′-bipyridinium." Scientific World Journal 2013 (2013): 1–8. http://dx.doi.org/10.1155/2013/452056.

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A series of 1-ethyl-1′-benzyl-4,4′-bipyridinium compounds with different counter anions (BEV-X2, where the X is Cl, Br, I, PF6, ClO4) were synthesized. By using of NMR, MS, electrochemistry, Na2S2O4-induced redox chemistry, and UV-Vis, the role of the different counter anions in the host-guest chemistry of cucurbit[8]uril (CB[8]) was studied for the first time. The result demonstrated that BEV-X2can form a 1 : 1 host-guest complex with CB[8] in water. Theoretical calculation further suggested that the viologen region was threaded through the cavity of CB[8], while the corresponding counter anions were located outside the cavity. Some difference can be observed on UV-Vis titration and Na2S2O4-induced redox chemistry, which showed that the counter anions have some effect on the host-guest chemistry. All these provide new insights into CB[8] host-guest system.

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44

Shafei, Gamal M. S. El, and Afaf A. Zahran. "Structural and Textural Properties of Perchlorated and Persulphated Mixed (Hydr)Oxides of Zirconium and Titanium." Adsorption Science & Technology 20, no. 8 (October 2002): 707–22. http://dx.doi.org/10.1260/026361702321104219.

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Perchlorated and persulphated mixed hydroxides of zirconium and titanium were prepared by coprecipitation and impregnation in aqueous HClO4 or (NH4)2S2O8 solutions of 0.05, 0.10, 0.20 and 0.40 M concentrations. An alternate sequence of impregnation followed by calcination or vice versa was conducted and the samples obtained studied using XRD, FT-IR, pyridine titration and low-temperature (–196°C) nitrogen adsorption methods. XRD indicated that the presence of titanium stabilized the tetragonal modification of zirconia and almost completely prevented the usual tetragonal → monoclinic transformation upon calcination at 650°C. Both S2O82– and ClO4− anions at their lowest concentration level (0.05 M) partially retarded the crystallization which occurred upon calcination at 650°C in their absence. However, the two anions showed different effects. Whereas the perchlorate anion prevented the formation of a crystalline titania phase (anatase) to a greater extent than that of crystalline zirconia, the persulphate anion showed the opposite effect. Complete inhibition was observed with both anions at a concentration of 0.4 M. This effect was attributed to adsorption of the anions on the hydroxy species of zirconium and titanium formed initially, as demonstrated by IR spectroscopy which showed that the anions were of lower symmetry, viz. C2v, due to their bonding to the hydroxy species. Calcination at 650°C caused the material formed initially to lose virtually all its initial high surface area because of crystallization. The prevention of crystallization by added anions was reflected in the retention of a relatively high surface area even after calcination at 650°C. The recorded difference in the interactions of the anions with the hydroxy species formed initially was also reflected in the texture of the anion-modified solids. The protecting influence of the ClO4− anion increased with its increasing concentration in the system, whereas the corresponding effect with the S2O82– anion increased up to 0.10 M concentration and then decreased at higher concentrations.

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Brudzisz, Anna M., Damian Giziński, and Wojciech J. Stępniowski. "Incorporation of Ions into Nanostructured Anodic Oxides—Mechanism and Functionalities." Molecules 26, no. 21 (October 22, 2021): 6378. http://dx.doi.org/10.3390/molecules26216378.

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Anodic oxidation of metals leads to the formation of ordered nanoporous or nanotubular oxide layers that contribute to numerous existing and emerging applications. However, there are still numerous fundamental aspects of anodizing that have to be well understood and require deeper understanding. Anodization of metals is accompanied by the inevitable phenomenon of anion incorporation, which is discussed in detail in this review. Additionally, the influence of anion incorporation into anodic alumina and its impact on various properties is elaborated. The literature reports on the impact of the incorporated electrolyte anions on photoluminescence, galvanoluminescence and refractive index of anodic alumina are analyzed. Additionally, the influence of the type and amount of the incorporated anions on the chemical properties of anodic alumina, based on the literature data, was also shown to be important. The role of fluoride anions in d-electronic metal anodizing is shown to be important in the formation of nanostructured morphology. Additionally, the impact of incorporated anionic species, such as ruthenites, and their influence on anodic oxides formation, such as titania, reveals how the phenomenon of anion incorporation can be beneficial.

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46

Witte, J. Felix, Janos Wasternack, Shenquan Wei, Christoph A. Schalley, and Beate Paulus. "The Interplay of Weakly Coordinating Anions and the Mechanical Bond: A Systematic Study of the Explicit Influence of Counterions on the Properties of (Pseudo)rotaxanes." Molecules 28, no. 7 (March 30, 2023): 3077. http://dx.doi.org/10.3390/molecules28073077.

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Weakly coordinating anions (WCAs) have attracted much attention in recent years due to their ability to stabilise highly reactive cations. It may well be argued, however, that a profound understanding of what truly defines a WCA is still lacking, and systematic studies to unravel counterion effects are scarce. In this work, we investigate a supramolecular pseudorotaxane formation reaction, subject to a selection of anions, ranging from strongly to weakly coordinating, which not only aids in fostering our knowledge about anion coordination properties, but also provides valuable theoretical insight into the nature of the mechanical bond. We employ state-of-the-art DFT-based methods and tools, combined with isothermal calorimetry and 1H NMR experiments, to compute anion-dependent Gibbs free association energies ΔGa, as well as to evaluate intermolecular interactions. We find correlations between ΔGa and the anions’ solvation energies, which are exploited to calculate physico-chemical reaction parameters in the context of coordinating anions. Furthermore, we show that the binding situation within the (pseudo)rotaxanes can be mostly understood by straight-forward electrostatic considerations. However, quantum-chemical effects such as dispersion and charge-transfer interactions become more and more relevant when WCAs are employed.

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47

Huang, Sai, Mei Yang, Xin-Yu Deng, Qian Jiang Zhu, Ying Huang, Zhu Tao, and Kai Chen. "Trans-4-[4-(dimethylamino)styryl]-1-methylpyridinium Iodide@Hemimethylcucurbit[6]uril Fluorescent Probe for Anion Recognition." Australian Journal of Chemistry 72, no. 7 (2019): 533. http://dx.doi.org/10.1071/ch19119.

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In the present work, a host–guest system of a hemimethyl-substituted cucurbit[6]uril derived from 3α-methyl-glycoluril (HMeQ[6]) and a hemicyanine dye, trans-4-[4-(dimethylamino)styryl]-1-methylpyridinium iodide (t-DSMI) showing strong fluorescence emission has been evaluated as a fluorescent probe. The results of a preliminary systematic study on the detection of a series of inorganic anions have revealed that this Q[n]-based host–guest fluorescent probe shows clear responses to BF4− and H2PO4− anions through distinct fluorescence quenching. Application of this Q[n]-based host–guest interaction system in anion recognition or detection opens a new avenue in Q[n] chemistry.

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Stíbr, Bohumil. "New carboranes and phosphaboranes." Pure and Applied Chemistry 75, no. 9 (January 1, 2003): 1295–304. http://dx.doi.org/10.1351/pac200375091295.

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A review is presented on the new routes to the synthesis of the monocarbaboranes [arachno-6-CB9H14]–, arachno-4-CB8H14, and nido-1-CB8H12, that now have become excellent starting materials for the preparation of a family of seven-, eight-, and nine-vertex closo-monocarbaborane anions [2-CB6H7]–, [1-CB7H8]–, and [4-CB8H9]–. These anions exhibit high stability and have a good chance to become new candidates for weakly coordinated anion chemistry. Discussed are also reactions leading new families of phosphacarboranes that contain one, two, and three phosphorus atoms in the cage. These compounds, namely closo- 2,1-PCB8H9, closo-6,1-PCB8H9, nido -7,8,9-PC2B8H11, nido-7,8,11-PC 2B8H11, and nido- 7,8,9,10-P3CB7H8 ,are structural analogs of the corresponding carboranes and are likely to exhibit similar chemical behavior.

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Mangelinckx, Sven, Nicola Giubellina, and Norbert De Kimpe. "1-Azaallylic Anions in Heterocyclic Chemistry." Chemical Reviews 104, no. 5 (May 2004): 2353–400. http://dx.doi.org/10.1021/cr020084p.

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Zhang, Yanjie, and Paul S. Cremer. "Chemistry of Hofmeister Anions and Osmolytes." Annual Review of Physical Chemistry 61, no. 1 (March 2010): 63–83. http://dx.doi.org/10.1146/annurev.physchem.59.032607.093635.

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Journal articles on the topic 'Anions (Chemistry)'

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