Search

CAAC precursors 2‐chloro‐3,3‐dimethylindole 1 and 2‐chloro‐1‐ethyl‐3,3‐dimethylindolium tetrafluoroborate 2BF4 have been prepared and oxidatively added to [M(PPh3)4] (M=Pd, Pt). Salt 2BF4 reacts with [Pd(PPh3)4] in toluene at 25 °C over 4 days to yield complex cis‐[3]BF4 featuring an N‐ethyl substituted CAAC, two cis‐arranged phosphines and a chloro ligand. Compound trans‐[3]BF4 was obtained from the same reaction at 80 °C over 1 day. Salt 2BF4 reacts with [Pt(PPh3)4] to give cis‐[4]BF4. The neutral indole derivative 1 adds oxidatively to [Pt(PPh3)4] to give trans‐[5] featuring a CAAC ligand with an unsubstituted ring‐nitrogen atom. This nitrogen atom has been protonated with py⋅HBF4 to give trans‐[6]BF4 bearing a protic CAAC ligand. The PdII complex trans‐[7]BF4 bearing a protic CAAC ligand was obtained in a one‐pot reaction from 1 and [Pd(PPh3)4] in the presence of py⋅HBF4., Cyclic (alkyl)(amino)carbene (CAAC) precursor salt 2BF4 reacts with [M(PPh3)4] (M=Pd, Pt) to give cis/trans‐[3]BF4 and cis‐[4]BF4, in which the CAAC ligand bears an unusual N‐alkyl substituent. trans‐[5] has a unique anionic CAAC ligand with an unsubstituted ring‐nitrogen atom which can be protonated to give trans‐[6]BF4 bearing a protic CAAC (pCAAC) ligand.

Gel polymer electrolytes based on tetraalkylammonium tetrafluoroborate (TEA BF4) were prepared and their electrochemical properties were studied. The impedance spectroscopy method was used to calculate electrical conductivity of electrolytes in different temperatures. Linear sweep voltammetry studies were performed to determine electrochemical stability of gel polymer electrolytes.

This work comprises the separation of an azeotropic mixture (hexane/ethyl acetate) with two different ionic liquids, viz, (1-ethyl-3-methylimidazolium tetrafluoroborate, [EMIM][BF4], and 1-ethyl-3-...

This work studied the separation effect of 1-hexyl-3-methylimidazolium-based ionic liquids (1-hexyl-3-methylimidazolium tetrafluoroborate [HMIM][BF4] and 1-hexyl-3-methylimidazolium trifluoromethan...

Pore–ion size matching between carbon electrodes and electrolytes is crucial for superior energy storage. However, it remains a great challenge to engineer carbons with perfectly compatible pore dimension for desired electrolytes. Herein we design a simple synthetic route to obtain carbon hydrangeas integrated with unique geometry, high surface areas, N/O doping, and more importantly, well-developed pore structure. The narrow primary subnanopores of 0.80 nm are exactly matched the cation sizes (EMIM+, 0.76 nm) of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIMTFSI) and 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4) ionic liquid electrolytes. Besides, the secondary pores of 0.50 nm are size-exclusively accessible for small BF4− anions (0.48 nm) but exclude larger TFSI− (0.79 nm), giving enhanced ion diffusion/adsorption kinetics. The solid-state supercapacitor based on EMIMBF4 gel electrolyte achieves an ultrahigh specific energy of 101.2 Wh kg−1 (29.2% enhancement against the use of EMIMTFSI), superior to the most values of recently reported carbon-based supercapacitors. This study opens new horizons to develop functionalized carbons with perfectly ion-comparable pore architecture, moving toward advanced energy storage systems.

The refractive indexes of three ionic liquids, glutamic acid tetrafluoroborate ([GA]BF4), glutamic acid double trifluoromethyl sulfonyl amine salts ([GA]TF2N), glutamic acid hexafluorophosphate ([GA]PF6), with ethanol and/or water systems under 10~35 °C were studied. The excessive refractive index of the systems and the relationship between the refractive index and the constituent molar fraction at 20 °C, and the empirical relationship between the excess refractive rate and the constituent mole fraction were established. The experimental results show that the excess refractive index is positive in the measured concentration range, and the refractive index of ethanol+water with the increase in the composition appears maximum and the refractive index of ethanol/water+ [GA]BF4, ethanol/water+[GA]PF6, ethanol/water+[GA]TF2N system is increased with the increase in composition. By using the Redlich-Kister equation to correlate the binary system and the excess refractive index of ternary system, the fitting results show that the refractive index of ternary system can be estimated using the refractive index of the polynomial equation of binary system.

Analysis of anticancer drugs is very important and necessary for the correct administration of them in the human body. Electrochemical behavior of 6-thioguanine (6-TG) has been studied using a carbon paste electrode modified by 1-ethyl-3-methylimidazolium tetrafluoroborate (ionic liquid) (1E3MIBF4) and CuO nanoparticles (CuO/1E3MIBF4/CPE). Using square wave voltammetry showed the linear relation between net anodic current and concentration of 6-TG in the range of 70 nmol L - 1 to 520 mmol L - 1 6-TG with the detection limit of 20 nmol L - 1 6-TG. The proposed modified electrode had excellent repeatability (RSD = 1.31%, n = 5) and long term stability (2.9% deviation in 25 days). The diffusion coefficient of 6-TG on the CuO/1E3MIBF4/CPE was found to be 1.54 × 10 - 5 cm 2 s − 1 .The CuO/1E3MIBF4/CPE was successfully applied for the determination of 6-TG in real samples. In addition, the anodic peaks of 6-TG and fluorouracil (5-FU) in their mixture can be well separated using CuO/1E3MIBF4/CPE and simultaneous determination of them was studied.

In this study the solubility of Hydrogen Sulfide (H2S) in four ionic liquids: 1-Ethyl-3-methylimidazoliom Hexafluorophosphate [Emim][PF6], 1-Ethyl-3-ethylimidazolium Tetrafluoroborate [Emim][BF4], 1-Ethyl-3-methylimidazolium Trifluromethanesulfonate [Emim][OTf] and 1-Ethyl-3-methylimidazolium Bistrifluoromethylsulfonilimide [Emim][NTf2] at temperature 343.15 K and relevant pressure has been simulated and the accuracy of obtained data compared to experimental ones. By comparing the radial distribution function of the [Emim]+-based ionic liquids with above-mentioned anions, it is found that the existence of H2S impacts the interactions between anion and cation and also the most appropriate anion among those, is [NTf2] which can properly solve H2S in its own.

Sodium-ion-based energy storage devices in which the electrochemical properties are influenced by excess Na ions are very important as an alternative energy storage system. In this study, O3-type multi-metal-oxide layers of Na3Ni2BiO6 were synthesized via a simple solid-state method. Their electrochemical properties were examined while employing them as a supercapacitor electrode material with four different electrolytes: H2SO4, Na2SO4, KOH, and 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4). Among these, BMIMBF4 ionic liquid electrolyte in a symmetric Na3Ni2BiO6 supercapacitor demonstrated the highest specific capacitance performance of 780.49 F g−1 at 0.5 A g−1 with 95.2% capacitance retention after 10,000 cycles. Moreover, a maximum energy density of 67.16 Wh·kg−1 was recorded at 349.87 W·kg−1. The enhanced electrochemical performance is a result of the reinforced fast intercalation/deintercalation of Na+ ions in the Na3Ni2BiO6 crystal structure due to high solvation and association mechanism of Na3Ni2BiO6 in BMIMBF4 ionic liquid media. These results indicate that the developed Na3Ni2BiO6-based supercapacitor with BMIMBF4 ionic liquid electrolyte could be used in the high-performance energy storage devices for smart electrical and electronic units.

In this study, we examined the low-frequency spectra of 1-methyl-3-octylimidazolium tetrafluoroborate ([MOIm][BF4]) mixtures with methanol (MeOH), acetonitrile (MeCN), and dimethyl sulfoxide (DMSO)...

In this project, we performed an electrochemical investigation using a reduced graphene (rG) decorated CdO nanocomposite/1-methyl-3-octylimidazolium tetrafluoroborate ionic liquid (MOITF) carbon paste electrode (rG-CdO/MOITF/CPE) for determination of ferulic acid in food samples. In preparation of rG-CdO/MOITF/CPE, 6% w/w rG-CdO nanocomposite and 20% v/v room temperature ionic liquid were used to modify the bare CPE. SEM (Scanning Electron Microscopy) and XRD (X-Ray Diffraction) methods were applied to characterize the structure of the synthesized rG-CdO nanocomposite. At all the stages of this research, phosphate buffer solution (PBS) with the pH of 5.0, as an optimized pH condition, was used. The electron transfer coefficient (α) was obtained ⁓0.68 by recorded data from cyclic voltammogram of rG-CdO/MOITF/CPE in the presence of ferulic acid. In addition, using the chronoamperometric technique, the diffusion coefficient (D) of ferulic acid at rG-CdO/MOITF/CPE was calculated 5.4 × 10−5 cm2/s. Using the square wave voltammetry method, the linear dynamic range (LDR) was calculated to be from 0.02 to 400 μM, and the limitation of detection (LOD) was obtained as 8.0 nM. Eventually, the rG-CdO/MOITF/CPE was utilized to determine the amount of ferulic acid in food samples, and statistical calculations confirmed the sensitivity, selectivity, and precision of rG-CdO/MOITF/CPE, which is an electroanalytical tool.

For the first time, we report a novel electrochemical sensor for the simultaneous detection of ethambutol (ETB) and pyrazinamide (PZM) using 1-ethyl-3-methylimidazolium tetrafluoroborate ([Emim][BF4]) ionic liquid (IL) assimilated with multiwalled carbon nanotubes (MWCNTs) decorated cobalt ferrite nanoparticles (CoFe2O4NPs) on the surface of glassy carbon electrode (GCE). The surface morphological and electrochemical properties of the IL@CoFe2O4NPs@MWCNTs was characterized with X-ray diffraction (XRD), transmission electron microscope (TEM), thermogravimetric analysis (TGA), fourier transform infrared spectroscopy (FTIR) and cyclic voltammetry (CV), differential pulse voltammetry (DPV) respectively. Moreover, the obtained results of CV demonstrated that the 9-folds enhancement in the electrochemical signals was achieved with IL@CoFe2O4NPs@MWCNTs@GCE compared to that of a bare GCE. Additionally, the simultaneous electrochemical detection of ETB and PZM was successfully accomplished using IL@CoFe2O4NPs@MWCNTs over a wide-range of concentration with good limit of detection (3S/m) of 0.0201 and 0.010 μM respectively. The findings of this study identify IL@CoFe2O4NPs@MWCNTs@GCE has promising abilities of simultaneous detection of ETB and PZM in pharmaceutical formulations.

Electropolymerisation of pyrrole was carried out in the presence of two ionic liquids: 1-hexyl-2,3-dimethylimidazolium tetrafluoroborate and 1,2-dimethylimidazolium methylsulfate. Electrochemical t...

Molecules possessing harmine moiety are reported to exhibit marked fungicidal and bactericidal activities. In this study, various quinozilinium tetrafluoroborate salts were synthesized using acylic and cyclic oxoketene dithioacetals followed by cycloaromatization from Harmine. All of these synthesized compounds were characterized by 1H NMR, 13C NMR, Mass and CHN analysis. This methodology would find wide usage in the preparation of indolo quinozilinium -based library of small molecules useful for medicinal chemistry and in drug discovery.

IR-792 as near IR (NIR) laser dye was dissolved with different concentrations in two types of ionic liquids (ILs) of different anion and cation, 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide (EMIM TFSI) & 1-Butyl-3-methylimidazolium tetrafluoroborate (BMIM BF4), as the benign green solvent and in methanol (MeOH) as a standard solvent. The behavior of fluorescence of IR-792 dye was studied. The fluorescence of IR-792 dissolved in the ILs was heavily compared to organic solvent. Some photo-physical parameters of IR-792 were calculated. Mainly, IR-792 had a very low quantum yield of fluorescence with high intersystem crossing rate & fluorescence lifetime in picosecond range. Optical absorption and behavior of fluorescence for the rigorously the purified imidazolium ILs in the neat condition and effect of IR-792 on their fluorescence have been examined. The emission behavior of IR-792 in green solvents was independent upon the wavelength of excitation, while the emission behavior of green solvents dependent upon the wavelength of excitation whether in pure state or with NIR laser dye. At most, the intensity of fluorescence of ILs is dependent upon dye concentration.

The reaction of simple alkynoate salts with isolated arenediazonium tetrafluoroborate salts that had been pre-conditioned with the gold(I) catalyst AuCl(Me2S) led to the formation of cross-coupled products via a decarboxylative Sonogashira reaction process in modest yield and under mild conditions. The major by-product is a defunctionalized aryl moiety stemming from the diazonium salt, which competitively forms via hydrodediazonation. Good functional group tolerance and reaction site selectivity were attained in this limited investigation.

Analytical prospects of ionic liquids as the components of the microemulsion for polyphenols separation by microemulsion electrokinetic chromatography are explored. Imidazolium-based hydrophilic ionic liquid 1-hexadecyl-3-methylimidazolium chloride was used as a surfactant and hydrophobic ionic liquids 1-hexyl-3-methylimidazolium tetrafluoroborate and 1-hexyl-3-methylimidazolium bis(trifluormethylsulfonyl)imide were used as the oil phase. It was shown that the addition of ionic liquids into the microemulsion leads to a significant increase in the number of theoretical plates for catechins separation (in the range 200–650 ×103) in both cases. It was established that the use of hydrophobic ionic liquids 1-hexyl-3-methylimidazolium tetrafluoroborate and 1-hexyl-3-methylimidazolium bis(trifluormethylsulfonyl)imide increases the sensitivity and selectivity of the polyphenols separation compared to 1-hexadecyl-3-methylimidazolium chloride. The following composition of microemulsion was found to be optimal for the selective electrophoretic separation of catechins with ionic liquids as the oil phase: 0.6% (w/v) sodium dodecyl sulphate, 0.7% (w/v) 1-hexyl-3-methylimidazolium tetrafluoroborate, 1.6% (w/v) 1-butanol, 5 mM phosphate buffer solution, pH = 7. The conditions for the electrophoretic separation of catechins with microemulsion electrokinetic chromatography were used to determine polyphenols in tea samples.

In our investigation, N-doped active carbon with the shape of nanospheres with a diameter of 85 nm was synthesized. The TEM image shows that the NAC has graphitic regions and the surface graphitic (002) plane can be observed. The specific surface area of NAC was 2256 m2/g. XPS demonstrated that elemental nitrogen (pyrrolic-N, pyridine-N, quaternary-N) was successfully doped into the active carbon structure with a total N content of 8.1%. The sample was tested in a symmetrical system in 1 M LiClO4/acetonitrile electrolyte and 1-ethyl-3-methylimidazolium tetrafluoroborate. It showed a high specific energy density of 65.3 Wh/kg, due to the high potential window in the 1-ethyl-3-methylimidazolium tetrafluoroborate. It could retain 95% of the initial capacitance even after 8000 cycles.

Series of oligomeric ionic liquid crystals (OILCs) based on various anions including bromide (Br−), tetrafluoroborate (BF4 −), dodecylbenzenesulphonate (A-SO3 −) and (+)-10-camphorsulphonate (D-SO3...

The possibility of electrochemical intercalation of tetrafluoroborate anion into graphite from a supercritical electrolyte containing carbon dioxide, acetonitrile as a co-solvent, and tetrabutylammonium tetrafluoroborate has been demonstrated for the first time.

This work presents a successfulness of the methodology of solution cast technique for fabrication of polymer blend electrolytes based on chitosan (CS): potato starch (PS) doped with various amounts of ammonium tetrafluoroborate (NH4BF4). In this work we demonstrated that association of ions is the main drawback for the NH4BF4 salt. Low DC conductivity of the films displays the non availability of the present system for applications. To look at the electrical properties, structural, and morphological properties, electrochemical impedance spectroscopy (EIS), X-ray diffraction (XRD), and Field emission scanning electron microscopy (FESEM), respectively were used. From the EIS measurement the highest conductivity of the system was found to be 3.07 × 10−8 S/cm which is too low for device applications including batteries and supercapacitors. The increase of bulk resistance is an indication for the recombination of cation and anion of the salt at high concentration. Sharp peaks were observed in the XRD spectra at high salt concentration. The morphological outcomes display protruded salts with large size at high salt concentration. The large value of dielectric constant at low frequency region is associated to electrode polarization (EP) while their decline with increasing frequency is ascribed to the lag of polarization of ion with respect to the quick orientation of dipole species because of the applied AC field. The M″ peak asymmetry displays the distribution of relaxation time.

Ionic liquid 1-butyl-3-methylimidazoluim tetrafluoroborate (BMIM+BF4−) was used for preparation of composite membranes containing ZnO nanoparticles. A poly(ethylene oxide) (PEO) composite membrane was used for CO2/N2 separation. The high selectivity of ZnO/BMIM+BF4− membrane was already studied. It was found that when ZnO nanoparticles were dispersed with an ionic liquid (BMIM+BF4−), the permeance of CO2 was significantly enhanced to 101 GPU, compared to the neat ionic liquid BMIM+BF4− membrane to show 17.0 GPU. However, the previously studied ZnO/BMIM+BF4− composites separation membrane was the liquid state membrane. In the case of liquid-state membrane, the liquid could be easily penetrated into the membrane support over time. Thus, since the thickness of the membrane becomes thicker, the separation performance of the membrane would be reduced. In order to overcome these problems, the solid-state membranes were required. Therefore, in this study the separation performance of CO2 and N2 by adding ZnO/BMIM+BF4− composites into poly(ethylene oxide) as polymer matrix.

L-2-[18 F]fluoro-alpha-methylphenylalanine (2-[18 F]FAMP) is a promising amino acid tracer for positron emission tomography (PET) imaging, yet the low production yield of direct electrophilic radiofluorination with [18 F]F2 necessitates further optimization of the radiolabeling process. This paper describes a two-step preparation method for L-2-[18 F]fluoro-alpha-methylphenylalanine (2-[18 F]FAMP) starting from [18 F]fluoride. The (Mesityl)(L-alpha-methylphenylalanine)-2-iodonium tetrafluoroborate precursors with various protecting groups were prepared. The copper-mediated 18 F-fluorination of the iodonium salt precursors successfully produced 2-[18 F]FAMP. The highest radio chemical conversion of 57.6% was noted with N-Piv-protected (mesityl)(aryl)iodonium salt in the presence of 5 equivalent of Cu (OTf)2 . Subsequent deprotection with 57% hydrogen iodide produced 2-[18 F]FAMP within 120 min in 21.4 ± 11.7% overall radiochemical yield with >95% radiochemical purity and an enantiomeric excess >99%. The obtained 2-[18 F]FAMP showed comparable biodistribution profiles in normal mice with that of the carrier-added 2-[18 F]FAMP. These results indicate that usefulness of copper mediated 18 F-fluorination for the production of 2-[18 F]FAMP, which would facilitate clinical translation of the promising tumor specific amino acid tracer. Individual facilities could adopt either production method based on radioactivity demand and equipment availability.

In this research, N-butyl-pyridinium tetrafluoroborate ([BPy][BF4]) ionic liquid (IL) was synthesized and characterized by 1H-NMR, 13C-NMR, and FT-IR spectroscopy. The synthesized ionic liquid was employed as an extractive agent for the removal of dibenzothiophene (DBT), a typical organosulfur pollutant from the organic medium. The effect of extractive desulfurization on a model fuel with DBT was investigated. The impact of operating parameters, i.e., temperature, extraction time, IL-to-fuel ratio, and fuel to oxidizing agent ratio, on the extraction efficiency was investigated. It was observed that the IL to model fuel ratio and the H2O2 dosage have significant effects on desulfurization efficiency. An 89.49% DBT removal efficiency was obtained at a temperature of 30 °C after 35 min of extraction when the volume ratio of IL:model fuel:H2O2 was 1:1:0.04. A density functional theory (DFT) study was carried out to investigate the interactions between the IL and the sulfur-containing compounds DBT/DBTO2.

The connection of a sterically constrained 3-methyl-pyrazine ring to a N-methyl-benzimidazole unit to give the unsymmetrical &alpha, &alpha, &rsquo, diimine ligand L5 has been programmed for the design of pseudo-octahedral spin-crossover [Fe(L5)3]2+ units, the transition temperature (T1/2) of which occurs in between those reported for related facial tris-didentate iron chromophores fitted with 3-methyl-pyridine-benzimidazole in a LaFe helicate (T1/2 ~ 50 K) and with 5-methyl-pyrazine-benzimidazole L2 ligands (T1/2 ~350 K). A thorough crystallographic analysis of [Fe(L5)3](ClO4)2 (I), [Ni(L5)3](ClO4)2 (II), [Ni(L5)3](BF4)2∙H2O (III), [Zn(L5)3](ClO4)2 (IV), [Ni(L5)3](BF4)2∙1.75CH3CN (V), and [Zn(L5)3](BF4)2∙1.5CH3CN (VI) shows the selective formation of pure facial [M(L5)3]2+ cations in the solvated crystals of the tetrafluoroborate salts and alternative meridional isomers in the perchlorate salts. Except for a slightly larger intra-strand interannular twist between the aromatic heterocycles in L5, the metric parameters measured in [Zn(L5)3]2+ are comparable to those reported for [Zn(L2)3]2+, where L2 is the related unconstrained ligand. This similitude is reinforced by comparable ligand-field strengths (∆oct) and nephelauxetic effects (as measured by the Racah parameters B and C) extracted from the electronic absorption spectra recorded for [Ni(L5)3]2+ and [Ni(L2)3]2+. In this context, the strictly high-spin behavior observed for [Fe(L5)3]2+ within the 5&ndash, 300 K range contrasts with the close to room-temperature spin-crossover behavior of [Fe(L2)3]2+ (T1/2 = 349(5) K in acetonitrile). This can be unambiguously assigned to an intraligand arm wrestling match operating in bound L5, which prevents the contraction of the coordination sphere required for accommodating low-spin FeII. Since the analogous 3-methyl-pyridine ring in [Fe(L3)3]2+ derivatives are sometimes compatible with spin-crossover properties, the consequences of repulsive intra-strand methyl&ndash, methyl interactions are found to be amplified in [Fe(L5)3]2+ because of the much lower basicity of the 3-methyl-pyrazine ring and the resulting weaker thermodynamic compensation. The decrease of the stability constants by five orders of magnitude observed in going from [M(L2)3]2+ to [M(L5)3]2+ (M = NiII and ZnII) is diagnostic for the operation of this effect, which had been not foreseen by the authors.

In this study, different ionic liquids including 1-aminoethyl-3-methyl-imidazolium bromide [C2NH2mim][Br] (1), 1-methyl-3-octylimidazolium chloride [C8mim][Cl] (2) and 1-methyl-3-octylimidazolium tetrafluoroborate [C8mim][BF4] (3) were applied to stabilize Pd nanoparticles (NPs) at toluene/water interface as thin films. Field emission-scanning electron microscopy (FE-SEM) images showed puckered chains of ionic liquid (1) around the Pd NPs as flower nanostructures. Transmission electron microscopy (TEM) image of Pd/1 showed clearly core–shell nanostructures. Furthermore, applications of Pd/1, Pd/2 and Pd/3 were investigated in the Suzuki–Miyaura C–C coupling reaction in the presence and absence of ultrasonic waves, hydrogenation catalysis of p-nitrophenol reduction and methanol oxidation reaction. Interestingly, Jf (forwarding current density due to methanol oxidation) was observed only for Pd/1. We believe that interactions of –NH2 and imidazolium groups of ionic liquid 1 with Pd particles are very important in producing of puckered shells around the Pd NPs. Injection of electron density from –NH2 group and Br− of ionic liquid 1 to Pd content tends to Pd be softer than other ionic liquids (2 or 3). This effect weakens the strength of Pd–O and facilitates the intermolecular reductive elimination between Pd–O and Pd–C≡O in rate-determining step of methanol oxidation to produce CO2 product. However, electron releasing group accelerates the increasement in negative charge density of metal accelerates intramolecular or intermolecular reduction elimination. Stabilization of Pd nanoparticles from organometallic precursor in the presence of various ionic liquids is investigated. The obtained Pd/ionic liquid thin films were applied in catalytic reactions such as Suzuki–Miyaura C–C coupling reaction, p-nitrophenol reduction and methanol oxidation process for fuel cells. In spite of Pd nanoparticle thin films used for methanol oxidation reaction that exhibit no considerable methanol oxidation, these catalysts exhibit good electrocatalytic activity.

The Biofine process is the currently used method for the industrial production of levulinic acid (LA) from biomass. In this process sulfuric acid is used to catalyze the reaction, the former is a corrosive and toxic catalyst. In this work, an environmental friendly catalyst: 1-butyl-2,3-dimethylimidazolium tetrafluoroborate ([BMMim][BF4]) was used to optimize the LA production from depithed sugarcane bagasse (DSB). The Box–Behnken design (response surface methodology) was used to design the set of experiments with three variables, namely, time, temperature and catalyst loading. The optimum condition for water as a solvent was 100 °C, 7 h and 4 g of a catalyst which yielded a maximum amount of 44.8% of LA from DSB. When different solvents were investigated at the optimum condition for LA production, methyl isobutyl ketone (MIBK) was the best solvent (54.2%). This study also showed that [BMMim][BF4] is capable of theoretically producing 62.1% of LA. The reusability study showed that [BMMim][BF4] can be used for up to four times without losing it activity.

Selectfluor, [1-chloromethyl-4-fluoro-1,4-diazoniabicyclo-[2.2.2]octane bis(tetrafluoroborate)], is not only an important electrophilic fluorinating agent but also a facile and efficient "fluorine-free" functional reagent in other organic reactions. In this Minireview, we will present a brief history of Selectfluor as a transition metal oxidant, fluorine cation and radical initiator in "fluorine-free" functionalizations over the last five years.

For three binary mixtures composed of ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]) with 2-propanol, N,N‑dimethylacetamide (DMA) and N,N‑dimethylformamide (DMF), the values of the experimental density and viscosity over the whole composition range for T = (293.15 to 323.15 K) are reported. Excess molar volume $$\mathop V\nolimits_{{\text{m}}}^{{\text{E}}}$$, partial molar volume $$\overline{{V_{i} }}$$, and the deviation in viscosity $$\Delta \eta$$ are calculated and explained in order to clarify the intermolecular interactions among the species in the mixtures. For all of the binary mixtures, the negative values of $$\mathop V\nolimits_{{\text{m}}}^{{\text{E}}}$$ and $$\Delta \eta$$ were fitted with the Redlich–Kister polynomial function. An increase in temperature decreases the values of $$\mathop V\nolimits_{{\text{m}}}^{{\text{E}}}$$ and increases the values of $$\Delta \eta$$. The results have been discussed regarding binary interaction forces and the formation of a complex between dissimilar molecules. For the correlation and prediction of the binary system densities, perturbed chain statistical associating fluid theory (PC-SAFT) was used. The results obtained from this theory are consistent with the experimental data.

In this article, we report the simultaneous determination cholesterol (CL), ascorbic (AA) acid and uric acid (UA) at a carbon paste electrode (CPE) modified with copper oxide decorated reduced graphene (CuO-rGR), with 1-methyl-3-octylimidazolium tetrafluoroborate (1M3OIDTFB) as a binder. The electrode, CuO-rGR/1M3OIDTFB/CPE, showed remarkable sensitivities towards the determination of the analytes, and well defined and clearly separated oxidation peaks were obtained during their simultaneous analysis in a buffer solution at pH 7.4. The differences observed between their peaks potentials are as follows: 430 mV (between CL and AA), 270 mV (between AA and UA) and 700 mV (between CL and UA). The morphologies and structure properties of the CuO-rGR were investigated by FESEMD and EDAX methods. The CuO-rGR/1M3OIDTFB/CPE displayed linear response in the concentration ranges 0.04–300.0 μM, 0.04–240.0 μM and 0.4–400.0 μM for CL, AA and UA with the detection limits 9.0 nM, 9.0 nM and 0.08 μM, respectively. The CuO-rGR/1M3OIDTFB/CPE displayed high performance for the determination of CL, AA and UA in real samples.

The solubility of theobromine and theophylline in seven pure imidazolium-based ionic liquids, including 1-butyl-3-methylimidazolium tetrafluoroborate ([C4mim]BF4), 1-butyl-3-methylimidazolium hexafluorophosphate ([C4mim]PF6), 1-butyl-3-methylimidazolium nitrate ([C4mim]NO3), 1-hexyl-3-methylimidazolium tetrafluoroborate ([C6mim]BF4), 1-hexyl-3-methylimidazolium hexafluorophosphate ([C6mim]PF6), 1-hexyl-3-methylimidazolium nitrate ([C6mim]NO3), and 1-octyl-3-methylimidazolium tetrafluoroborate ([C8mim]BF4), were measured via a static method combined with high-performance liquid chromatography between T = 303.15–353.15 K at atmospheric pressure. The solubility of theobromine and theophylline in the selected ionic liquids increased as the temperature increased. Both cations and anions in the ionic liquids affected the solubility, but anions had a more pronounced effect than the cations with a trend of NO3– > BF4– > PF6–. The simplified dual-parameter equation, the Apelblat empirical equation, and the λh equa...

We performed classical Molecular Dynamics computer simulations to analyze solutions of the gases CO2, N2, and CH4 in four 1-n-butyl-3-methylimidazolium-based ionic liquids (1-n-butyl-3-methylimidazolium acetate, 1-n-butyl-3-methylimidazolium prolinate, 1-n-butyl-3-methylimidazolium bromide, and 1-n-butyl-3-methylimidazolium tetrafluoroborate). Typical experimental conditions (10 bar gas pressure and room temperature) have been chosen to study mixtures of the ionic liquids with the gases at a single gas molar fraction of 0.25. Structural aspects are discussed to judge the absorption capacities of the ionic liquids. We observed that CO2 coordinates preferentially within the polar domain of the ionic liquids with the bromide and tetrafluoroborate anions presenting the best performances. The other gases, N2 and CH4, remain in the less polar domains of the ionic liquids. Cluster size analysis indicates phase separation for these two gases. Considering both, the absorption tendency and gas separation capacity of the ionic liquids, the anion is desired to be small and possessing multiple coordination sites. In this aspect, the tetrafluoroborate anion accomplished the best results.

A protocol of visible-light-promoted C2 selective arylation of quinoline and pyridine N-oxides, with diaryliodonium tetrafluoroborate as an arylation reagent, using eosin Y as a photocatalyst for the construction of N-heterobiaryls was presented. This methodology provided an efficient way for the synthesis of 2-aryl-substituted quinoline and pyridine N-oxides. This strategy has the following advantages: specific regioselectivity, simple operation, good functional group tolerance, and high to moderate yields under mild conditions.

The nanofriction coefficient of ionic liquids (ILs), 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) and 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]), on the surfaces of mica and graphite was investigated using atomic force microscopy (AFM). A pronounced layered spatial distribution was found in the IL film formed on the solid substrates and can be divided into 3 well distinguishable regions exhibiting different physical properties with increasing distance from the substrate. We found that the friction coefficient (μ) increases monotonically as the layering thickness decreases, no matter what the thickness of the bulk IL is. This suggests that the layering assembled IL at solid surfaces is more important than the bulk phase in determining the magnitude of the nanoscale friction. The increase in the friction coefficient as the layering thickness decreases is most likely attributed to the assembled ordered IL layers closer to the substrate surfaces having a greater activation barrier for unlocking the surfaces to allow shear.

AA7075-xZrB2 (x = 0, 5, 10, 15, and 20 wt.%) composites were manufactured by reacting potassium zirconium fluoride (K2ZrF6) and potassium tetrafluoroborate (KBF4) with molten AA7075 at 800°C. The ZrB2 particles formed by the reaction were fairly uniformly distributed throughout the whole composite. The microhardness of the composites increased from 45 to 78 VHN with ZrB2 contents from 0 to 20 wt.%, respectively. The wear rate rose as the load and sliding distance increased and fell as the sliding speed increased. The material-removal mechanism of the composites was due to abrasive wear.

In this work, a series of experiments were carried out to study the kinetic inhibition performance of N-butyl-N-methylpyrrolidinium tetrafluoroborate ([BMP][BF4]), poly(N-vinylcaprolactam) (PVCap) and compound inhibitor systems on methane hydrate from both macroscopic and microscopic perspectives. In the macroscopic experiments, the influence of the concentration, the ratio of inhibitors, the subcooling on the induction time and gas consumption rate of methane hydrate were studied. The results indicated that [BMP][BF4] could inhibit the growth rate of CH4 hydrate, but failed to delay the nucleation. An improved inhibitory effect was observed by combining [BMP][BF4] and PVCap, and the optimal ratio of the two inhibitors was obtained to gain the best inhibition performance. Furthermore, the microstructure and morphology of methane hydrate crystals formed in different inhibitor systems were investigated through powder X-ray diffraction (PXRD), Raman spectroscopy and scanning electron cryomicroscopy (Cryo-SEM) methods. It was found that [BMP][BF4] and PVCap had different influences on the large cage occupancy by CH4 and the morphology of methane hydrate.

Three novel coordination compounds, [Cu(ca)2(Hbae)2] (1), [Cu(va)2(Hbae)2] (2) and [Cu4(va)4(bae)4]·H2O (3), have been prepared by self-assembly reactions of copper(ii) chloride (1 and 2) or tetrafluoroborate (3) and CH3OH (1 and 3) or CH3CN (2) solution of 2-benzylaminoethanol (Hbae) and cinnamic (Hca, 1) or valeric (Hva, 2 and 3) acid. Crystallographic analysis revealed that both 1 and 2 have mononuclear crystal structures, wherein the complex molecules are H-bonded forming extended supramolecular chains. The tetranuclear structure of 3 is based on the {Cu4(μ3-O)4} core, wherein the metal atoms are bound together by μ3 oxygen bridges from 2-benzylaminoethanol forming an overall cubane-like configuration. The strong hydrogen bonding in 1-3 leads to the joining of the neighbouring molecules into 1D chains. Concentration-dependent ESI-MS studies disclosed the equilibria between di-, tri- and tetranuclear species in solutions of 1-3. All three compounds act as catalysts for the aerobic oxidation of o-aminophenol to the phenoxazinone chromophore (phenoxazinone synthase-like activity), with the maximum reaction rates of 4.0 × 10-7, 2.5 × 10-7 and 2.1 × 10-7 M s-1 for 1, 2 and 3, respectively, supported by the quantitative yield of the product after 24 h. The dependence of the reaction rates on catalyst concentrations is evidence of reaction orders higher than one relative to the catalyst. Kinetic and ESI-MS data allowed us to assume that the tetranuclear species, originating from 1, 2 and 3 in solution, possess considerably higher activity than the species of lower nuclearity. Mechanistic and isotopic 18O-labelling experiments suggested that o-aminophenol coordinates to CuII species with the formation of reactive intermediates, while the oxygen from 18O2 is not incorporated into the phenoxazinone chromophore.

The behavior of aqueous solutions of mixtures of ionic liquids (ILs) is of special interest because of their amphiphilic character, from both a fundamental and application viewpoint. In this work, we conducted molecular dynamics (MD) simulations and density functional theory (DFT) calculations to understand the effect of water on the intermolecular interactions in three IL binary mixtures [C4mim]/[Cl]/[BF4], [C4mim]/[Cl]/[PF6] and [C4mim]/[BF4]/[PF6] containing the well-characterized cation, 1-n-butyl-3-methylimidazolium [C4mim]+ and the anions chloride [Cl]-, tetrafluoroborate [BF4]-, and hexafluorophosphate [PF6]-. The perturbation of the structures in the binary IL mixture by water molecules was analyzed in the bulk and at the liquid/vacuum interface using distribution functions, hydrogen-bond statistics, and density profiles. Interactions between anions and cations change drastically when the IL mixtures are dissolved in water. In particular, anion-water interactions are stronger than anion-cation interactions. H-Bonds are the dominant interactions. They are prevalently electrostatic and strong for the two [Cl]-containing systems in both the water-free and the water-containing systems. The very hydrophobic [C4mim]/[BF4]/[PF6] system gains stability from dispersive interactions and consequently segregates water markedly when admixed. The most probable orientations of IL cations in the bulk and at the vicinity of the interface were examined using bivariate distribution calculations and show [PF6]- segregating to the surface in keeping with its highly hydrophobic nature. DFT calculated structures, energies, dipole moments, global hardness and solvation energies using model ion pairs [C4mim][X] or complexes [C4mim]2[X][Y], with [X/Y]- = [Cl]-, [BF4]-, or [PF6]- are completely consistent with the findings for the bulk.

To obtain a better understanding of TiO2 nanotube (TiO2-NT) synthesis in different ethylene glycol (EG)-based electrolyte solutions by electrochemical anodization, the primary steps of TiO2-NT formation were studied by experimental techniques. In this regard, three different EG-based electrolyte solutions were used for anodic oxidation of titanium foil. The first electrolyte solution contains conventional ammonium fluoride (NH4F) dissolved in EG/water (98 : 2 v/v). In the second one, Ti foil anodization is performed in an electrolyte solution containing the 1-butyl-3-methyl-imidazolium tetrafluoroborate (Bmim-BF4) ionic liquid. Finally, the fluorine-containing species was replaced by the 1-butyl-3-methyl-imidazolium chloride (Bmim-Cl) ionic liquid. The results indicate that the TiO2-NTs did not form by anodization in the EG/H2O/Bmim-Cl electrolyte solution at 60 V. Interestingly, this electrolyte solution is less viscous than the fluorine-containing electrolyte solutions. In addition, we report a detailed study on the structural arrangement of electrolyte solution components near the solid surfaces using molecular dynamics (MD) simulation methods to reveal the factors governing the difference of the ionic species distribution. The MD results elucidate the role of the ionic constituents in the length of the nanotube arrays at a certain anodization condition. Furthermore, as reported herein for the first time, the lifetimes of ion–ion contacts and the interactions of ionic species with TiO2 walls have a substantial effect on the resulting nanotubes. These characteristics are analyzed by using radial distribution functions, density profiles, distance analysis, time correlation functions, and mean-square-displacements, complemented by DFT calculations.

Hydrophobic ionic liquids containing bis(trifluoromethanesulfonyl)imide, [NTf2]-, anions partially dissolve in aqueous phases. The potential ecotoxicity of [NTf2]- means wastewater streams must be closely monitored to avoid environmental release. A new ion chromatography method is presented, which improves on existing techniques and methods by significantly decreasing analysis time and improving chromatographic peak properties. Consequently, the limit of detection is lowered to 5 μM (1.4 ppm) and limit of quantification lowered to 30 μM (8.5 ppm). The method is reproducible and has a high precision for short and medium chain length ionic liquids (RSD = 0.95%); however, microemulsion effects increase measurement errors for long chain ionic liquids (RSD = 2.32%), albeit by a relatively small amount. Hence, the method is a highly accurate analytical method for highly polarizable [NTf2]- anions, and quantification in the presence of high salinity samples, such as seawater, is readily achieved. Importantly, this method is a significant improvement on existing techniques (chromatography, NMR, UV-Vis) for many reasons, making it ideal for environmental monitoring or process design of [NTf2]- ionic liquid-based applications.

The material dispersion of the [Ckmim][BF4] (k = 2, 3, 4, 6, 7, 8, 10) family of ionic liquids is measured at several temperatures over a broad spectral range from 300 nm to 1550 nm. The experimental curves are fitted to a modified three-resonance Sellmeier model to understand the effects of temperature and alkyl chain length on the dispersion behaviour. From the parameters of the fitting, we analyze the influence that the different constituents of these ionic liquids have on the dispersion behaviour. In addition, a semi-empirical approach combining simulated electronic polarizabilities and experimental densities for predicting the material dispersion is successfully tested by using a direct comparison with the experimental results. The limitations of this method are analyzed in terms of the molecular structure of the ionic liquids. The results of this work aim to increase our knowledge about how the molecular structure of an ionic liquid influences its material dispersion. Understanding this influence is fundamental to producing ionic liquids with tailored optical properties.

We report the synthesis of PEGylated imidazolium (bromide and tetrafluoroborate) and tris-imidazolium (bromide) salts containing triazole linkers, and their use as stabilizers for the preparation of water-soluble gold nanoparticles by reduction of tetrachloroauric acid with sodium borohydride. The nanomaterials have been characterized. The X-Ray Photoelectron Spectroscopy (XPS) indicated the presence of Au(I) and Au(0) species, the oxidized form being more abundant in the nanomaterial derived from the tris-imidazolium bromide. The catalytic activity of these gold nanoparticles has been proved in the A3 coupling between carbonyl compounds, terminal alkynes and amines to afford propargylamines, and in the cycloisomerization of γ-alkynoic acids to enol lactones. The nanomaterial derived from the PEG-tagged tris-imidazolium bromide provided the best performance and it has been recycled in both reactions (up to four and six runs) taking advantage of its solubility properties.

Johnson-Corey-Chaykovsky fluorocyclopropanation of double activated alkenes utilizing S-monofluoromethyl-S-phenyl-2,3,4,5-tetramethylphenylsulfonium tetrafluoroborate is an efficient approach to obtain a range of monofluorocyclopropane derivatives. So far, fluoromethylsulfonium salts have displayed the broadest scope for direct fluoromethylene transfer. In contrast to more commonly used fluorohalomethanes or freon derivatives, diarylfluoromethylsulfonium salts are bench stable, easy-to use reagents useful for the direct transfer of a fluoromethylene group to alkenes giving access to the challenging products - fluorocyclopropane derivatives. Interplay between the reactivity of the starting materials and stability of the fluorocyclopropanes formed determines the outcome of the process.

The synthesis of 4,5-diiodo-1,3-dimesityl-1,2,3-triazolium salts with different anions have been developed. These triazolium salts show diverse aggregation via halogen bonding between C–I bonds and anions. Triazolium with halide anions exists as a tetramer with saddle conformation. Triazolium tetrafluoroborate exists as a trimer with Chinese lantern shape conformation. Triazolium trifluoroacetate and acetate exist as dimers, respectively, while the former shows boat conformation and the latter forms rectangle conformation. Triazolium salts form a linear polymer with polyiodide.

In this work, we present a facile and effective protocol, the in situ tetrafluoroborate modification route, to improve the photoluminescence and stability of CH3NH3PbBr3 (MAPbBr3) nanocrystals by directly introducing tetrafluoroborate salts into the precursor solutions in the LARP process. It is found that the incorporation of tetrafluoroborate can control the optical properties and morphologies of the MAPbBr3 nanocrystals. By adjusting the amount of BF4−, the MAPbBr3 nanocrystals with tunable emission (480–525 nm) and high photoluminescence are acquired. Simultaneously, the stability of the MAPbBr3 nanocrystals can also be greatly improved via in situ tetrafluoroborate modification. More interestingly, the introduction of BF4− can induce the self-assembly crystal growth behavior of the MAPbBr3 nanocrystals, which exhibit orderly alignment and oriented self-assemblies. Such amazing results are primarily ascribed to the passivation of surface defects, the presence of a stable organic–inorganic hybrid ligand layer and formation of hydrogen bonding between BF4− and MA+ upon in situ incorporation of tetrafluoroborate.

This work reports the mutual diffusion coefficients of carbon dioxide - 1-Butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) system at different temperatures (313.15 and 323.15 K) and pressu...

By the interaction of Nb(NMe2)5 and 1,3-(2,6-diisopropylphenyl)imidazolium (IPr·HBF4) tetrafluoroborate a binuclear complex with coordinated N-heterocyclic carbene [(IPr)Nb(=NMe)(NMe2)(μ-F)2(μ-NMe2) NbF2(NMe2)] (1) is obtained. The reaction of Nb(NMe2)5 and 1,3-(2,4,6-trimethylphenyl)imidazolium (IMes·HBF4) tetrafluoroborate yields [(IMes)2H][NbF6] salt (2). The structure of the complexes is determined by single crystal X-ray diffraction.

The density and viscosity of 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF4] and 1-butyl-3-methylimidazolium chloride [BMIM][Cl] and their binary mixtures within the temperatures from 303.15 K to 323.15 K and at ambient pressure were determined in this work. The temperature dependences of density and viscosity were satisfactorily described with the linear model and the Vogel-Tammann-Fulcher type equation, respectively. The molar volume and viscosity of binary IL mixtures were predicted through ideal mixing rules showing that almost null deviations for IL mixtures were observed and their mixing was remarkably close to linear ideal behavior in the molar volumes, while comparatively large errors in viscosity occurred. Additionally, the molar volume of the investigated pure ILs and their mixtures could well be predicted by a predictive model presented by Valderrama et al. (Fluid Phase Equilib., 275 (2009) 145).

To gain a deeper understanding of the TiCl4 solvation effects in multi-component ionic liquids, we performed ab initio molecular dynamics simulations of 1-butyl-3-methylimidazolium [C4C1Im]+, tetrafluoroborate [BF4]&minus, chloride [Cl]&minus, both with and without water and titanium tetrachloride TiCl4. Complex interactions between cations and anions are observed in all investigated systems. By further addition of water and TiCl4 this complex interaction network is extended. Observations of the radial distribution functions and number integrals show that water and TiCl4 not only compete with each other to interact mainly with [Cl]&minus, which strongly influences the cation-[BF4]&minus, interaction, but also interact with each other, which leads to the fact that in certain systems the cation-anion interaction is enhanced. Further investigations of the Voronoi polyhedra analysis have demonstrated that water has a greater impact on the nanosegregated system than TiCl4 which is also due to the fact of the shear amount of water relative to all other components and its higher mobility compared to TiCl4. Overall, the polar network of the IL mixture collapses by including water and TiCl4. In the case of [Cl]&minus, chloride enters the water continuum, while [BF4]&minus, remains largely unaffected, which deeply affects the interaction of the ionic liquid (IL) network.