CF3 SO3 Research Articles

Catalyst-Free Intermolecular Sulfonyl/Fluoromethyl Heteroarylation of Vinyl Ethers via Visible-Light-Induced Charge Transfer.

We report a visible-light-induced three-component sulfonyl-heteroarylation of vinyl ethers with sulfinates and five-membered heteroaryl chlorides. This protocol proceeds via electron-donor-acceptor (EDA) complexes between sulfinates and heteroaryl chlorides, giving β-sulfonyl alkyl five-membered heteroarenes with high efficiency and excellent regioselectivity under mild and catalyst-free conditions. Utilization of CF3 SO2 Na or CF2 HSO2 Na as coupling partners further achieves three-component fluoromethyl-arylation of vinyl ethers, furnishing a series of valuable CF3 /CF2 H-incorporated alkyl heterocycles under mild conditions.

Fluoro-nitrogen Cations.

The crystal structures of [NH3 F]+ [CF3 SO3 ]- , [NH2 F2 ]+ [SbF6 ]- , and [N2 F3 ]+ [Sb3 F16 ]- have been determined, representing the first structural characterizations of these simple fluoro-nitrogen cations. The influences of the hybridization of the central nitrogen atom and of the number of fluorine substituents on the N-F bond lengths are evaluated for the series N2 F+ , N2 F3 + , NF2 O+ , NH3 F+ , NH2 F2 + , and NF4 + . It is shown that the N-F bond length decreases from 1.40 Å to 1.26 Å with increasing fluorine substitution and increasing s-character of the nitrogen atom, and that unusual N-F bond lengths reported in the previous literature are caused by disorder problems.

Mechanistic Insight on the Solid Electrolyte Interphase (SEI) Formed By a Superconcentrated [Li][TFSI] in Acetonitrile Electrolyte Near Lithium Metal

Superconcentrated salt solutions are promising alternatives to conventional electrolytes in Li-ion batteries because of their enhanced redox stability and tendency to form a stable and rigid solid electrolyte interphase (SEI). Herein, we performed density functional theory-based molecular dynamics (DFT-MD) simulations to understand the initial electrode reactions between the Li metal and superconcentrated electrolyte solution of Li bis(trifluoromethanesulfonyl)imide ([Li][TFSI]) in acetonitrile (AN). We thoroughly analyzed the structure and composition of the SEI formed near the Li metal. We show that reductive decomposition of the TFSI anions contributes majorly in the initial SEI formation and the AN molecules are relatively stable against the redox processes occurring near the Li metal. The atomized C, O, F, and S atoms contributed by the TFSI anions forms the stable inorganic layer leading to highly structured and inhomogeneous SEI. The AN molecules and undissociated N–SO2–CF3 fragments are mostly aligned away from the Li layers. Figure 1

Preparation of Porous Polymers Based on the Building Blocks of Cyclophosphazene and Cage-like Silsesquioxane and Their Use as Basic Catalysts for Knoevenagel Reactions.

Phosphazene-containing porous materials are of a great interest due to their unique properties, caused by the synergetic presence of nitrogen and phosphorus atoms, and have found applications as adsorbents, basic catalysts, etc. On the other hand, cage-like silsesquioxanes are ideal building blocks for the preparation of covalently-linked porous materials. Here two new phosphazene-functionalized organosilsesquioxane cage-based porous polymers were synthesized successively by a Friedel-Crafts reaction of hexapyrrolylcyclotriphosphazene with octavinylsilsesquioxane in the presence of AlCl3 and CF3 SO3 H as catalysts. The nature of acid catalysts barely influenced the character of pores due to the interaction of catalysts with basic nitrogen atoms of phosphazene units. The obtained polymers exhibited high efficiency as metal-free catalysts for the Knoevenagel reaction. This work opens new perspectives in the use of porous polymers based on cage-like organosiloxane compounds as basic catalysts for various reactions.

A Fluorinated Carbanionic Substituent for Improving Water Solubility and Lipophilicity of Fluorescent Dyes.

Installation of a carbanionic substituent, that is strongly stabilized by two (trifluoromethyl)sulfonyl (Tf=SO2 CF3 ) groups, into several fluorescence dyes including boron-dipyrromethenes (BODIPYs), fluoresceins, and aminocoumarins has been achieved by the 2,2-bis(triflyl)ethylation reaction of the dye frameworks with highly electrophilic Tf2 C=CH2 , followed by neutralization with NaHCO3 . Despite the contradiction between water solubility and lipophilicity, the carbanion-decorated dyes thus obtained showed significant enhancement of not only water solubility but also lipophilicity. This work clearly demonstrates that the fluorinated, highly stabilized carbanionic substituent is a new option for controlling the macroscopic property of chemical materials.

Tertiary-Amine-Initiated Synthesis of Acyl Fluorides from Carboxylic Acids and CF3 SO2 OCF3.

A convenient method for deoxyfluorination of aromatic and aliphatic carboxylic acids with CF3 SO2 OCF3 in the presence of a suitable base at room temperature has been developed. The reaction allows a straightforward access to a variety of acyl fluorides and proves that CF3 SO2 OCF3 is an effective deoxyfluorination reagent for carboxylic acids. The method features simplicity, expeditiousness, high efficiency, ease of handling, good functional group tolerance, a wide range of substrates, excellent yields of products, compatibility of many amine initiators, use of environmentally friendly reagents, and effortless removal of byproducts. This reaction represents the first utilization of trifluoromethyl trifluoromethanesulfonate as a fluorination reagent.

Attempts to Synthesize a Thiirane, Selenirane, and Thiirene by Dealkylation of Chalcogeniranium and Thiirenium Salts.

Thiiranium salts [Ad2SR]+X− (5, 8, 9, 11, 12; X−=Tf2N− (Tf=CF3SO2), SbCl6 −) and seleniranium salts [Ad2SeR]+X− (14, 16, 17, 23–25; X−=Tf2N−, BF4 −, CHB11Cl11 −, SbCl6 −) are synthesized from strained alkene bis(adamantylidene) (1). The disulfides and the diselenides (Me3SiCH2CH2E)2 (4, 13), (tBuMe2SiCH2CH2E)2 (7, 22), and (NCCH2CH2E)2 (10, 15; E=S, Se) have been used. The thiirenium salts [tBu2C2SR]+X− (34) and [Ad2C2SR]+X− (35, 36) are prepared from the bis‐tert‐butylacetylene (2) and bis‐adamantyl‐acetylene (3) with R=Me3SiCH2CH2 and tBuMe2SiCH2CH2. Attempts to cleave off the groups Me3SiCH2CH2, tBuMe2SiCH2CH2, and NCCH2CH2 resulted in thiiranes 27, 30. No selenirane Ad2Se (33) is formed from seleniranium salts, instead cleavage to the alkene (1) and diselenide (13, 15) occurs. The thiirenium salt [Ad2C2SCH2CH2SiMe3]+Tf2N− (35) does not yield the thiirene Ad2C2S (37), the three‐membered ring is cleaved, forming the alkyne (3) and disulfide (4). All compounds are characterized by ESI mass spectra, NMR spectra, and by quantum chemical calculations. Crystal structures of the salts 8, 12, 25, 17, 26, 36 and the thiiranes 27, 30 are presented.

In Situ Construction of a LiF-Enriched Interface for Stable All-Solid-State Batteries and its Origin Revealed by Cryo-TEM.

The application of solid polymer electrolytes (SPEs) is still inherently limited by the unstable lithium (Li)/electrolyte interface, despite the advantages of security, flexibility, and workability of SPEs. Herein, the Li/electrolyte interface is modified by introducing Li2 S additive to harvest stable all-solid-state lithium metal batteries (LMBs). Cryo-transmission electron microscopy (cryo-TEM) results demonstrate a mosaic interface between poly(ethylene oxide) (PEO) electrolytes and Li metal anodes, in which abundant crystalline grains of Li, Li2 O, LiOH, and Li2 CO3 are randomly distributed. Besides, cryo-TEM visualization, combined with molecular dynamics simulations, reveals that the introduction of Li2 S accelerates the decomposition of N(CF3 SO2 )2 - and consequently promotes the formation of abundant LiF nanocrystals in the Li/PEO interface. The generated LiF is further verified to inhibit the breakage of CO bonds in the polymer chains and prevents the continuous interface reaction between Li and PEO. Therefore, the all-solid-state LMBs with the LiF-enriched interface exhibit improved cycling capability and stability in a cell configuration with an ultralong lifespan over 1800 h. This work is believed to open up a new avenue for rational design of high-performance all-solid-state LMBs.

Initiating a Reversible Aqueous Zn/Sulfur Battery through a "Liquid Film".

Sulfur cathodes have been under intensive study in various systems, such as Li/S, Na/S, Mg/S, and Al/S batteries. However, to date, Zn/S chemistry has never been reported. The first reliable aqueous Zn/polysulfide system activated by a "liquid film" comprising 4-(3-butyl-1-imidazolio)-1-butanesulfoni ionic liquid (IL) encapsulated within PEDOT:PSS. CF3 SO3 - anions in the IL operating as Zn2+ -transfer channels is reported. Moreover, the PEDOT:PSS network retains the IL, which renders Zn2+ -transfer channels and a polysulfide cathode with enhanced structural stability. The Zn/polysulfide system delivers extraordinary capacity of 1148 mAh g-1 and overwhelming energy density of 724.7 Wh kg-1 cathode at 0.3 Ag-1 . During the discharging phase, S6 2- is dominantly reduced by Zn to S2- (S6 → S2- ). During the charging phase, these short chains are oxidized to form long-chain Znx Liy S3-6 . A further optimized high-concentrated salt electrolyte is used to improve the reversibility of the battery, demonstrating an extended lifetime over 1600 cycles at 1 Ag-1 with a capacity retention of 204 mAh g-1 . This facile approach and the superior performance of the developed aqueous Zn/S chemistry provide a new platform for sulfur-based battery and potentially solve the problems of other metal/sulfur batteries.

Self-Assembled, Highly Positively Charged, Allyl-Pd Crowns: Cavity-Pocket-Driven Interactions of Fluoroanions.

A series of dodecanuclear highly positively charged homo- and heterometallamacrocycles [{Pd(η3 -2-Me-C3 H4 )}6 (4-PPh2 py)12 {M2 (tpbz)}3 ]18+ (M=Pd, Pt; tpbz=1,2,4,5-tetrakis(diphenylphosphanyl)benzene were synthesized by the quantitative self-assembly of {Pd(η3 -2-Me-C3 H4 )}+ , {M2 (tpbz)}4+ and 4-PPh2 py moieties in 2:1:4 molar ratio. The cationic assemblies were obtained as salts of different fluorinated anions with diverse sizes and electronic properties, namely BF4 - , PF6 - , SbF6 - and CF3 SO3 - . The new crown-like metallamacrocycles showed remarkable differences in their NMR spectra due to the presence of the different counteranions. On the basis of the observed variations, the metallacycles have been tested as catalytic precursors in allylic alkylation reactions. The anion-dependent activity and selectivity has been analysed and compared with that of the corresponding monometallic allylic corners [Pd(η3 -2-Me-C3 H4 )(4-PPh2 py)2 ]X (X=BF4 - , PF6 - , SbF6 - , CF3 SO3 - ). DFT calculations have been employed in order to help to the interpretation of the experimental data and to model the anion-crown interactions.

Light-driven coordination anions-directed regulation of chromism in three metal complexes assembled by cyano-equipped dithienylethene ligand

Three coordination compounds were self-assembled successfully with Ag(I) ions and photo-responsive ligands featuring a cyano-equipped dithienylethene unit. Anions with different coordinating abilities were selected to construct distinct topologies, which are evidenced by X-ray crystallographic analysis. CF3 COO− and CF3 SO3− are involved into coordination in 1 and 3, respectively, whereas in 2 BF4− present merel y as ionic guests counterbalancing the framework charge. Anions also show their subtle effects on coordinated atoms, interactions, and ligand configurations. The quite different structures of 1–3 indicate an interesting anion-directed structural self-assembly.Followed examinations on photochromism illustrated that the reversible photo-isomerizations of three complexes are all retained after complexzation with Ag(I) center. Various degrees of bathochromic shifts in absorptions were observed as compared with that of the metal-free ligand. Therefore, the photo-switching of these compounds could be modulated conveniently and finely by varying simply the coordination anions and then triggering by light irradiation. The discussions of structure-properties relationship concluded that anions exert their effects on coordination structure through adjusting the configurations of ligands in complexes. Strong coordinating anions facilitate a pronounced conformational change of ligand whereas un-coordinating anion leads to smaller variation. The distinct structural changes of ligand result finally the different perturbation of photochromic behavior.

A High-Power Aqueous Zinc-Organic Radical Battery with Tunable Operating Voltage Triggered by Selected Anions.

In contrast to traditional rechargeable rock-chair metal-ion batteries, dual-ion batteries (DIBs) involve redox reactions with anions rather than cations in p-type cathodes. In principle, regulating the electrochemical performance of the DIB by different anion species is highly feasible. Herein, the anion effect on the electrochemical performance of a DIB, the aqueous Zn- organic radical battery (Zn-ORB), consisting of a poly(2,2,6,6tetramethylpiperidinyloxy-4-yl vinyl ether) cathode and a Zn anode, was investigated by DFT calculations. SO4 2- , CF3 SO3 - , and ClO4 - with different molecular electrostatic potential values were selected as anion models. DFT calculations revealed that a stronger electrostatic interaction of the anion with the organic radical resulted in a higher operating voltage of the Zn-ORB, which was consistent with experimental results. These results bring new insight into the redox chemistry of p-type organic radicals with anions and will promote the development of high-power aqueous Zn-ORBs as well as inspire more investigations into the anion effect towards novel battery designs.

Electrophotocatalytic Undirected C-H Trifluoromethylations of (Het)Arenes.

Electrophotochemistry has enabled arene C−H trifluoromethylation with the Langlois reagent CF3SO2Na under mild reaction conditions. The merger of electrosynthesis and photoredox catalysis provided a chemical oxidant‐free approach for the generation of the CF3 radical. The electrophotochemistry was carried out in an operationally simple manner, setting the stage for challenging C−H trifluoromethylations of unactivated arenes and heteroarenes. The robust nature of the electrophotochemical manifold was reflected by a wide scope, including electron‐rich and electron‐deficient benzenes, as well as naturally occurring heteroarenes. Electrophotochemical C−H trifluoromethylation was further achieved in flow with a modular electro‐flow‐cell equipped with an in‐operando monitoring unit for on‐line flow‐NMR spectroscopy, providing support for the single electron transfer processes.

Solid-State [2+2] Photodimerization of 1-Aryl-4-pyridylbutadienes in Cation-π-Controlled Crystals.

Irradiation of HX (X=CF3 SO3 or CF3 CO2 ) salts of 1-aryl-4-pyridylbutadienes 1 a-1 c in the solid-state afforded syn head-to-tail dimers in good yields among a number of possible dimers, whereas irradiation of the neutral substrates gave a complex mixture or no products. A comparison of the X-ray crystal structures of the neutral compounds and the HX salts clarified that their orientation modes are head-to-head and head-to-tail, respectively. Moreover, while the distances between the two neighboring double bonds of the neutral compounds are relatively far apart from each other, those of HX salts are close together, satisfying Schmidt's requirement. These findings suggested that cation-π interactions between the pyridinium and aromatic rings are effective for the preorientation of the HX salts of substrates, leading to photodimers in high regio- and stereoselectivities.

Expanding the Electrochemical Window: New Tunable Aryl Alkyl Ionic Liquids (TAAILs) with Dicyanamide Anions.

A set of new tunable aryl alkyl ionic liquids (TAAILs) based on the 1-aryl-3-alkyl imidazolium motif has been synthesized, in which the following variables were systematically changed: alkyl chain length, aryl substitution (group and position), and counter ion. TAAILs with dicyanamide (DCA) and bis(trifluoromethylsulfonyl)imide (N(SO2 CF3 )2 , NTf2 ) anions showed remarkable differences of their physical properties: NTf2 ionic liquids were found to have high decomposition temperatures and viscosities well below those of the DCA TAAILs. In contrast, the dicyanamide anion increased the electrochemical stability leading to TAAILs with an extremely wide electrochemical window of up to 7.17 V. Additionally, both classes of TAAILs extract transition metals from aqueous solutions: TAAILs with the DCA anion extract both platinum and copper while TAAILs with the NTf2 anion are selective towards platinum. This demonstrates that minor changes of the molecular structure lead to TAAILs with drastically changed physicochemical properties.

Solvent-Free Production of Isosorbide from Sorbitol Catalyzed by a Polymeric Solid Acid.

A series of polymeric solid acid catalysts (PDSF-x) is prepared by grafting strong electron-withdrawing groups (-SO2 CF3 ) on a sulfonic acid-modified polydivinylbenzene (PDS) precursor synthesized hydrothermally. The effect of acid strength on sorbitol dehydration is investigated. The textural properties, acidity, and hydrophobicity are characterized by using Brunauer-Emmett-Teller analysis, elemental analysis, and contact angle tests. The results of FTIR spectroscopy and X-ray photoelectron spectroscopy show that both -SO3 H and -SO2 CF3 are grafted onto the polymer network. We used solid-state 31 P NMR spectroscopy to show that the acid strength of PDSF-x is enhanced significantly compared with that of PDS, especially for PDSF-0.05. As a result, PDSF-0.05 exhibits the highest isosorbide yield up to 80 %, a good turnover frequency of 231.5 h-1 (compared to other catalysts), and excellent cyclic stability, which is attributed to its large specific surface area, appropriate acid strength, hydrophobicity, and stable framework structure. In addition, a plausible reaction pathway and kinetic analysis are proposed.

Dual Roles of tert-Butyl Nitrite in the Transition Metal- and External Oxidant-Free Trifluoromethyloximation of Alkenes.

By employing tert-butyl nitrite as both nitrogen source and oxidant, the trifluoromethyloximation of alkenes proceeds smoothly in a free-radical process. The developed difunctionalization reaction enables practical and efficient synthesis of a wide range of α-CF3 ketoximes in moderate yields with excellent regioselectivity. This method features the use of readily available and stable alkenes as substrates and inexpensive CF3 SO2 Na as a CF3 reagent, no involvement of transition metals or external oxidant, and room-temperature conditions. Moreover, a scale-up of the reaction, further transformation of the products into various valuable CF3 -containing compounds, and removal of the trifluoromethyl group are readily achieved.

Concise and Additive-Free Click Reactions between Amines and CF3 SO3 CF3.

Trifluoromethyl trifluoromethanesulfonate has proved to be an excellent reservoir of difluorophosgene and a promising click ligation for amines in the preparation of urea derivatives, heterocycles, and carbamoyl fluorides under metal- and additive-free conditions. The reactions are rapid, efficient, selective, and versatile, and can be performed in benign solvents, giving products in excellent yields with minimal efforts for purification. The characteristics of the reactions meet the requirements of a click reaction. The use of trifluoromethyl trifluoromethanesulfonate as a click reagent is advantageous over other "CO" sources (e.g., TsOCF3 , PhCO2 CF3 , CsOCF3 , AgOCF3 , and triphosgene) because this reagent is readily accessible; easy to scale up; and highly reactive, even under metal- and additive-free conditions. It is anticipated that CF3 SO3 CF3 will be increasingly as important as SO2 F2 as a click agent in future drug design and development.

A Self-Healing Integrated All-in-One Zinc-Ion Battery.

The self-healing of zinc-ion batteries (ZIBs) will not only significantly improve the durability and extend the lifetime of devices, but also decrease electronic waste and economic cost. A poly(vinyl alcohol)/zinc trifluoromethanesulfonate (PVA/Zn(CF3 SO3 )2 ) hydrogel electrolyte was fabricated by a facile freeze/thaw strategy. PVA/Zn(CF3 SO3 )2 hydrogels possess excellent ionic conductivity and stable electrochemical performance. Such hydrogel electrolytes can autonomously self-heal by hydrogen bonding without any external stimulus. All-in-one integrated ZIBs can be assembled by incorporating the cathode, separator, and anode into hydrogel matrix since the fabrication of PVA/Zn(CF3 SO3 )2 hydrogel is a process of converting the liquid to quasi-solid state. The ZIBs show an outstanding self-healing and can recover electrochemical performance completely even after several cutting/healing cycles.

The Preparation of Luminescent, Mechanochromic Molecular Containers from Non-Emissive Components: The Box Cations, [Au6 (Triphos)4 Br]5+ and [Au6 (Triphos)4 Br2 ]4.

Two new molecular boxes, the mono-bromo box [Au6 (Triphos)4 Br](SbF6 )5 ⋅6(CH2 Cl2 ), 4 mB, and the dibromo box, [Au6 (Triphos)4 Br2 ⋅H2 O](SbF6 )4 ⋅4(CH2 Cl2 ), 5 dB, have been prepared in crystalline form. Although constructed from non-luminescent components, both are strongly luminescent. Like its chloro counterpart, the mono-bromo box [Au6 (Triphos)4 Br](SbF6 )5 ⋅6(CH2 Cl2 ), 4 mB, is mechanochromic. Under grinding, it loses its luminescence. The bromo-bridged helicate, [(μ-Br){Au3 (Triphos)2 }2 ](CF3 SO3 )5 ⋅2(CH2 Cl2 ), 3μ-H, with a cation that is isomeric with the box [Au6 (Triphos)4 Br]5+ , has also been prepared and crystallographically characterized. Unlike its chloro analogue, [(μ-Br){Au3 (Triphos)2 }2 ](CF3 SO3 )5 ⋅2(CH2 Cl2 ) is not luminescent. Thus, the cation produced upon grinding may be the cation present in the bromo-bridged helicate, [(μ-Br){Au3 (Triphos)2 }2 ](CF3 SO3 )5 ⋅2(CH2 Cl2 ), 3μ-H. The dibromo box, [Au6 (Triphos)4 Br2 ⋅H2 O](SbF6 )4 ⋅4(CH2 Cl2 ), 5 dB, is not significantly mechanochromic.