Various metal nanoparticles produced by accelerated electron beam irradiation of room-temperature ionic liquid

Various metal nanoparticles including base metal were produced by a brief accelerated electron beam irradiation of 1-alkyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)amide room-temperature ionic liquid without a stabilizing agent, which is usually employed so as to prevent aggregation.     

Hydrophobic, Highly Conductive Ambient-Temperature Molten Salts

New, hydrophobic ionic liquids with low melting points (<-30 degrees C to ambient temperature) have been synthesized and investigated, based on 1,3-dialkyl imidazolium cations and hydrophobic anions. Other imidazolium molten salts with hydrophilic anions and thus water-soluble are also described. The molten salts were characterized by NMR and elemental analysis. Their density, melting point, viscosity, conductivity, refractive index, electrochemical window, thermal stability, and miscibility with water and organic solvents were determined. The influence of the alkyl substituents in 1, 2, 3, and 4(5)-positions on these properties was scrutinized. Viscosities as low as 35 cP (for 1-ethyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)amide (bis(triflyl)amide) and trifluoroacetate) and conductivities as high as 9.6 mS/cm were obtained. Photophysical probe studies were carried out to establish more precisely the solvent properties of 1-ethyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)amide). The hydrophobic molten salts are promising solvents for electrochemical, photovoltaic, and synthetic applications.     

NMR and IR studies of bis((perfluoroalkyl)sulfonyl)imides

The influence of water on the NMR and IR spectra of bis((perfluoroalkyl)sulfonyl)imides has been investigated. The large effects of water on the observed spectra suggest that the proton is predominantly bound to the nitrogen of the perfluorosulfonimide acid in the absence of water, while it protonates water to form an onium salt in the presence of water.     

Synthesis and characterization of bis[bis(pentafluoroethyl)phosphinyl]imides, M(+)N[(C2F5)2P(O)]2(-), M = H, Na, K, Cs, Ag, Me4N

A convenient synthesis and a full characterization of the strong acid bis[bis(pentafluoroethyl)phosphinyl]imide and some of its salts M (+)N[(C 2F 5) 2P(O)] 2 (-), M = Na, K, Cs, Ag, Me 4N, are presented. Their thermal (mp, T dec.) and spectroscopic (IR, Raman, NMR) properties are discussed. A single crystal structure of [Me 4N][N{P(O)(C 2F 5) 2} 2] has been obtained, and the structural parameters of the anion are compared with the results of quantum-chemical calculations. The observed properties are comparable to those of bis((trifluoromethyl)sulfonyl)imide and their derivatives.     

Correlation between the fluorescent response of microfluidity probes and the water content and viscosity of ionic liquid and water mixtures

Accurate data on transport properties such as viscosity are essential in plant and process design involving ionic liquids. In this study, we determined the absolute viscosity of the ionic liquid + water system at water mole fractions from 0 to 0.25 for three 1-alkyl-3-methylimidazolium ionic liquids: 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide and 1-ethyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide. In each case, the excimer to monomer ratio for 1,m-bis(1-pyrenyl)alkanes (m= 3 or 10) was found to increase linearly with the mole fraction of water. Of the probes studied only PRODAN and rhodamine 6G, both of which have the ability to participate in hydrogen bonding, exhibited Perrin hydrodynamic behavior in the lower viscosity bis(trifluoromethane sulfonyl)imides. As a result, these probes allow for the extrapolation of the absolute viscosity of the ionic liquid mixture from the experimental fluorescence steady-state polarization values.     

Electrochemical Behavior of the Li+/Li Couple and Stability of Lithium Deposits in Tri‐1‐Butylmethylammonium Bis((Trifluoromethyl)Sulfonyl)Imide Room Temperature Ionic Liquid

The electrochemical behavior of the Li⁺/Li couple was studied at polycrystalline tungsten, platinum, copper and aluminum electrodes in tri‐1‐butylmethylammonium bis((trifluoromethyl)sulfonyl)imide ionic liquid mixed with a little propylene carbonate at 30 °C. Lithium cations were introduced into the ionic liquid by dissolution of lithium bis((trifluoromethyl)sulfonyl)imide which is highly soluble in ionic liquid. Propylene carbonate was used to reduce the viscosity of this ionic liquid in order to enhance the mass transfer and to additionally improve the stability of lithium deposits. At the tungsten and copper electrodes, the cyclic voltammetric behavior of a Li⁺/Li couple is a quasi‐reversible reaction. At the platinum electrode, the behavior becomes very complicated because of the alloy formation. Coulombic efficiency was used to evaluate the stability of lithium deposits at each electrode. The aluminum electrode showed the best efficiency due to the formation of Li‐Al alloy. However, lowest efficiency was obtained at the platinum electrode because of the low redox reversibility of the lithium in the Li‐Pt alloy. The diffusion coefficient of lithium cation in this solution was 1.0 ± 0.1 × 10^?;7 cm² s^?;1 as determined by chronopotentiometry. The best coulombic efficiency obtained at the Al electrode is 97% but dropped to about 90% after 12 hours. The self‐discharge current of the lithium deposits at the Al electrode was 0.4 μA/cm² during the experimental period.     

Bis‐Sulfonyl O,C,O‐Chelated Metallylenes (Ge,Sn) as Adjustable Ligands for Iron and Tungsten Complexes

The synthesis and characterization of an E₂CE₂ bis‐sulfonyl aryl pincer ligand and its efficiency for the stabilization of compounds containing low‐valent Group 14 elements (Ge and Sn) are reported. Complexation reaction of these metallylenes with iron or tungsten complexes resulted in the modulation of the oxygen atoms of the sulfonyl groups implicated in the stabilization of the Group 14 elements, demonstrating the original adjustable character of the bis‐sulfonyl O₂S‐C‐SO₂ aryl pincer.     

Chemical capacitance of nanoporous-nanocrystalline TiO2 in a room temperature ionic liquid

The electrochemical behaviour of nanoporous TiO(2) in a room temperature ionic liquid (RTIL), 1-ethyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)amide (EMITFSI), was investigated by cyclic voltammetry (CV) and impedance spectroscopy. Exponentially rising currents in voltammetry were attributed to the charging/discharging of electrons in the TiO(2) film and a charge transfer mechanism. The main features of the voltammetry and impedance followed the same trends in the ionic liquid as in other organic solvents and also in aqueous electrolytes. In the presence of lithium ions, the onset potential of the charge accumulation increased due to the change of the initial position of the TiO(2) conduction band. The results show that substitution of organic solvents contained in solar cells, supercapacitors or other electrochemical devices is in general feasible, though requires some adjustment in the electrolyte composition for optimal performance.     

Synthesis,Enantiomeric Conformations,and Stereodynamics of Aromatic ortho‐Substituted Disulfones

Aromatic ortho‐disulfone derivatives are readily accessible from diiodide precursors by Cu^I‐mediated reaction with sodium sulfinate salts (DMF, 110°). The sulfonyl substituents adopt in solution and in the solid state two enantiomeric conformations (λ and δ) as evidenced by ³¹P‐ and ¹H‐NMR data of the chiral D₃‐symmetric tris{4,5‐bis[(4‐methylphenyl)sulfonyl]benzene‐1,2‐diolato(2?)‐κO,κO′}phosphate(v) anion ( 3a ) and 1,2‐bis(camphor‐10‐sulfonyl)‐4,5‐dimethoxybenzene ((=1,2‐bis{{[(1S,4R)‐7,7‐dimethyl‐2‐oxobicyclo[2.2.1]hept‐1‐yl]methyl}sulfonyl}‐4,5‐dimethoxybenzene; 6c ). X‐Ray structure analysis of 1,2‐dimethoxy‐4,5‐bis(methylsulfonyl)benzene ( 6a ) and 1,2‐dimethoxy‐4,5‐bis(4‐methylphenyl)sulfonyl]benzene ( 6b ) confirmed in the solid state the preferred chiral orientation of the sulfonyl groups. Dynamic conformational isomerism was detected for 6c in its ¹H‐NMR in the temperature range of 110°, the corresponding free energy being 19.8 kcal?mol^?1.     

Chemical transformation of bis((perfluoroalkyl)sulfonyl)methanes and 1,1,3,3‐tetraoxopolyfluoro‐1,3‐dithiaycloalkanes

Halogenation of the potassium or silver salts of bis((trifluoromethyl)sulfonyl)methane(CF₃SO₂)₂CH₂ and its cyclo analogues (CF₂)_nSO₂‐CH₂SO₂CF₂ with N‐fluoro‐bis((trifluoromethyl)sul‐fonyl)imine (CF₃SO₂)₂NF, chlorine or bromine gave good yields of the corresponding α‐halo disulfones (CF₃SO₂)₂CHX and (CF₂)_nSO₂CHXSO₂CF₂ (X: F, Cl, Br; n = 1,2). Some chemical transformations of these fluorinated α‐halo‐disulfones are described. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 147–151, 1999     

Electrochemical behaviour of poly(3,4-ethylenedioxythiophene) in a room-temperature ionic liquid

The cyclic voltammetry responses and the redox switching dynamics of poly(3,4-ethylenedioxythiophene) (PEDOT) in a room-temperature ionic liquid, 1-ethyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)amide (EMImTf₂N), were investigated. The shape of the cyclic voltammograms showed two anodic and two cathodic peaks. These peak currents varied linearly with the scan rate indicating a thin-layer behaviour. No memory effects were observed during the cyclic voltammetry experiments in this ionic liquid. On the other hand, the redox switching dynamics of PEDOT were studied by means of potential step experiments. The analysis of chronocoulograms in term of RC-circuits indicated that the time dependence of the charge transferred during the potential step showed two time constants. These results were consistent with the postulated structure or morphology of the PEDOT film which contained two types of coexisting zones: a compact and an open structures.     

Efficient Synthesis of Chiral 1,1′‐Sulfonyl Bisaziridines

An efficient three‐step synthesis of chiral 1,1′‐(sulfonyl)bisaziridines is described. Preparation of these compounds was carried out easily starting from N,N′‐sulfonyl bis‐(α‐L‐aminoester) to afford the title compounds in very good yields. These 1,1′‐(sulfonyl)bisaziridines can constitute interesting synthetic building blocks.     

Extraction of Cupric Ions with Ionic Liquids Containing Polypyridine‐type Small Molecules or Peripherally Pyridine‐modified Dendrimers

The hydrophobic ionic liquid N‐butyl‐N‐methylpyrrolidinium bis((trifluoromethyl)sulfonyl)amide (BMP‐TFSA IL), which contains a series of flexible ionophores of polypyridine‐type small molecules or two rigid ionophores of peripherally pyridine‐modified PAMAM dendrimers, was used to extract cupric ions from aqueous solutions. The polypyridine‐type ionophores show good selectivity toward cupric ions at pH 2. The selectivity is affected by the spacing between the two amino groups. However, the pyridine‐modified dendrimers showed poor selectivity, although their extraction efficiency still depended on the pH of the aqueous solution. The ionic liquids that contained small molecular ionophores and their dendrimer analogs were reused after acid washing or electrochemical reduction. During acid washing, the nitrogen atoms of the ionophores were protonated to release the cupric ions into the aqueous phase, and the copper atoms were deposited onto the electrode surface during the electrochemical reduction accompanied by the regeneration of the ionophores.     

A Bis‐Sulfonyl O,C,O Aryl Pincer Ligand and its Tin(II) Complex: Synthesis,Structural Studies,and DFT Calculations

The efficiency of the deprotonated aryl bis‐sulfone [2,6‐{(p‐tolyl)SO₂}₂C₆H₃]^? as an O,C,O‐coordinating pincer‐type ligand was described. The bis‐sulfone precursor was synthesized using a straightforward palladium‐catalyzed cross‐coupling reaction. As a result of directed ortho metalation (DoM) through sulfonyl groups, a selective lithiation of the aryl group was achieved and the corresponding carbanion was isolated and its structure determined by single‐crystal X‐ray diffraction analysis. A heteroleptic tin(II) complex has been prepared by a nucleophilic substitution reaction. Crystallographic analysis and DFT calculations indicate that the bis‐sulfonyl moiety acts as a new O,C,O‐coordinating pincer‐type ligand with intramolecular S?O coordination to a tin(II) center. The cis form with the two nonbonded oxygen atoms of the sulfonyl groups on the same side is preferentially obtained.     

A Bis‐Sulfonyl O,C,O Aryl Pincer Ligand and its Tin(II) Complex: Synthesis,Structural Studies,and DFT Calculations

The efficiency of the deprotonated aryl bis‐sulfone [2,6‐{(p‐tolyl)SO₂}₂C₆H₃]⁻ as an O,C,O‐coordinating pincer‐type ligand was described. The bis‐sulfone precursor was synthesized using a straightforward palladium‐catalyzed cross‐coupling reaction. As a result of directed ortho metalation (DoM) through sulfonyl groups, a selective lithiation of the aryl group was achieved and the corresponding carbanion was isolated and its structure determined by single‐crystal X‐ray diffraction analysis. A heteroleptic tin(II) complex has been prepared by a nucleophilic substitution reaction. Crystallographic analysis and DFT calculations indicate that the bis‐sulfonyl moiety acts as a new O,C,O‐coordinating pincer‐type ligand with intramolecular SO coordination to a tin(II) center. The cis form with the two nonbonded oxygen atoms of the sulfonyl groups on the same side is preferentially obtained.     

A biomimetic sensor based on specific receptor ETBD and Fe3O4@Au/MoS2/GN for signal enhancement shows highly selective electrochemical response to ultra-trace lead (II)

Journal of Solid State Electrochemistry - A lead-chelating ligand, 2,2′-((1E)-((4-((2-mercaptoethyl)thio)-1,2phenylene)bis(azany-lylidene))bis(methanylylide-ne))diphenol (ETBD), was...     

Neutral-ligand complexes of bis(imino)pyridine iron: synthesis, structure, and spectroscopy

A family of bis(imino)pyridine iron neutral-ligand derivatives, ((iPr)PDI)FeL(n) ((iPr)PDI = 2,6-(2,6-iPr2-C6H3N=CMe)2C6H3N), has been synthesized from the corresponding bis(dinitrogen) complex, ((iPr)PDI)Fe(N2)2. When L is a strong-field ligand such as tBuNC or a chelating alkyl diphosphine such as DEPE (DEPE = 1,2-bis(diethylphosphino)ethane), a five-coordinate, diamagnetic compound results with no spectroscopic evidence for mixing of paramagnetic states. Reducing the field strength of the neutral donor to principally sigma-type ligands such as tBuNH2 or THT (THT = tetrahydrothiophene) also yielded diamagnetic compounds. However, the 1H NMR chemical shifts of the in-plane bis(imino)pyridine hydrogens exhibit a large chemical shift dispersion indicative of temperature-independent paramagnetism (TIP) arising from mixing of an S = 1 excited state via spin-orbit coupling. Metrical data from X-ray diffraction establish bis(imino)pyridine chelate reduction for each structural type, while M?ssbauer parameters and NMR spectroscopic data differentiate the spin states of the iron and identify contributions from paramagnetic excited states.     

Facile and reproducible syntheses of bis(dialkylselenophosphenyl)-selenides and -diselenides: X-ray structures of ((i)Pr2PSe)2Se, ((i)Pr2PSe)2Se2 and (Ph2PSe)2Se

Facile and reproducible methods for the syntheses of bis(di-iso-propylselenophosphinyl)selenide ((i)Pr2PSe)2Se (1), bis(di-iso-propylselenophosphinyl)diselenide ((i)Pr2PSe)2Se2 (2) and bis(di-phenylselenophosphinyl)selenide (Ph2PSe)2Se (3) is reported.     

Molybdenum(VI) complexes of a 2,2'-biphenyl-bridged bis(amidophenoxide): competition between metal-ligand and metal-amidophenoxide π bonding

The 2,2'-biphenyl-bridged bis(2-aminophenol) ligand 4,4'-di-tert-butyl-N,N'-bis(3,5-di-tert-butyl-2-hydroxyphenyl)-2,2'-diaminobiphenyl ((t)BuClipH(4)) reacts with MoO(2)(acac)(2) to form ((t)BuClipH(2))MoO(2), where the diarylamines remain protonated and bind trans to the terminal oxo groups. This complex readily loses water on treatment with pyridine or 3,5-lutidine to form mono-oxo complexes ((t)BuClip)MoO(L), which exhibit predominantly a cis-β geometry with an aryloxide trans to the oxo group. Exchange of the pyridine ligands is rapid and takes place by a dissociative mechanism, which occurs with retention of stereochemistry at molybdenum. Oxo-free alkoxide complexes ((t)BuClip)Mo(OR)(2) are formed from ((t)BuClipH(2))MoO(2) and ROH. Treatment of NMo(O(t)Bu)(3) with (t)BuClipH(4) results in complete deprotonation of the bis(aminophenol) and formation of a dimolybdenum complex ((t)BuClip)Mo(μ-N)(μ-NH(2))Mo((t)BuClip) containing both a bridging nitride (Mo-N = 1.848 ?, Mo-N-Mo = 109.49°) and a bridging amide group. The strong π bonding of this bis(amidophenoxide) ligand allows the molybdenum center to interconvert readily among species forming three, two, one, or zero π bonds from multiply bonded ligands.