A Liquid-State Tetrafluoroborate Ion-Selective Electrode Based on Brilliant Green Tetrafluoroborate

Abstract

A liquid-state ion-selective electrode which is sensitive to tetrafluoroborate ion, and which is based on Brilliant green tetrafluoroborate, has been developed. A chlorobenzene solution of the basic dye salt is absorbed into natural rubber sheeting which acts as the membrane in the electrode. At concentrations of tetrafluoroborate ion between 10^?4 and 10^?1 M a near Nernstian slope of 58.5 mV per decade change of concentration was obtained at 25°C; the potential response became steady within 1 minute at each concentration. Selectivity constants are given for a range of anions of which only perchlorate interferes markedly (K_{BF 4}-_{/ClO 4}- = 1.0 to 1.6).     

Electroanalysis of Benazepril Hydrochloride Antihypertensive Drug Using an Ionic Liquid Crystal Modified Carbon Paste Electrode

Electroanalysis of benazepril HCl was successful using a carbon paste electrode modified with an ionic liquid crystal ( 1‐butyl‐1‐methylpiperidinium hexafluorophosphate) in presence of sodium dodecyl sulfate. The electrode performance was compared to ionic liquids (1‐n‐hexyl‐3‐methyl imidazolium tetrafluoroborate and 1‐butyl‐4‐methyl pyridinium tetrafluoroborate). Electrochemical determination of benazepril HCl was in the linear dynamic range of 8.89×10^?7 to 1.77×10^?5 mol L^?1 (correlation coefficient 0.999) and LOD 7.17×10^?9 mol L^?1. benazepril HCl was determined using this sensor in presence of urine metabolites such as uric acid, ascorbic acid. Binary mixtures of dopamine/benazepril and amlodipine/benazepril were also determined successfully.     

Bioelectroanalytical Determination of Rutin Based on bi‐Enzymatic Sensor Containing Iridium Nanoparticles in Ionic Liquid Phase Supported in Clay

A matrix comprising iridium nanoparticles and 1‐butyl‐3‐methylimidazolium tetrafluoroborate ionic liquid (Ir‐BMI.BF₄) supported in montmorillonite (MMT) was obtained through an efficient incorporation process. This modified clay matrix (Ir‐BMI.BF₄‐MMT) was used for the immobilization of the enzymes laccase (LAC) and polyphenol oxidase (PPO) and employed in the construction of a bi‐enzymatic biosensor for determination of rutin by square‐wave voltammetry. Under optimized conditions, the analytical curve showed a linear range for rutin concentrations from 9.17×10^?8 to 3.10×10^?6 mol L^?1 with a detection limit of 3.09×10^?8 mol L^?1. The method was successfully applied to the determination of rutin content in pharmaceutical samples.     

Theoretical study of interactions between 1-alkyl-3-methyimidazolium tetrafluoroborate and dibenzothiophene: DFT,NBO, and AIM analysis

Density functional theory is employed to study the interaction energies between dibenzothiophene (DBT) and 1-alkyl-3-methylimidazolium tetrafluoroborate ([C _n mim]⁺[BF₄]^?). The structures of DBT, 1-ethyl-3-methylimidazolium tetrafluoroborate ([C₂mim]⁺[BF₄]^?), 1-butyl-3-methylimidazolium tetrafluoroborate ([C4mim]+[BF₄]?), 1-hexyl-3-methylimidazolium tetrafluoroborate ([C₆mim]⁺[BF₄]^?), 1-octyl-3-methylimidazolium tetrafluoroborate ([C₈mim]⁺[BF₄]^?), [C₂mim]⁺[BF₄]^?–DBT, [C₄mim]⁺[BF₄]^?–DBT, [C₆mim]⁺[BF₄]^?–DBT and [C₈mim]⁺[BF₄]^?–DBT systems are optimized systematically at the B3LYP/6-31G(d,p) level, and the most stable geometries are obtained by NBO and AIM analyses. The results indicate that DBT and imidazolium rings of ionic liquids are parallel to each other. It is found that the [BF₄]^? anion prefers to be located close to a C1–H9 proton ring in the vicinity of the imidazolium ring and the most stable gas-phase structure of [C _n mim]⁺[BF₄]^? has four hydrogen bonds between [C _n mim]+ and [BF₄]?. There are hydrogen bonding interactions, π–π and C–H–π interactions between [C₈mim]⁺[BF₄]^? and DBT, which is confirmed by NBO and AIM analyses. The calculated interaction energies for the studied ionic liquids can be used to interpret a better extracting ability of [C₈mim]⁺[BF₄]^? to remove DBT, due to stronger interactions between [C₈mim]⁺[BF₄]^? and DBT, in agreement with the experimental results of dibenzothiophene extraction by [C _n mim]⁺[BF₄]^?.     

A Novel Category of Ionic Liquids Based on Diacetone Acrylamide Cation and Their Use as Esterification Catalysts

A novel category of salts based on diacetone acrylamide cation （DA^＋） and the anions such as acetate （Ac^-）, trifluoroacetate （TF^-）, tetrafluoroborate （BF^-）, hexafluorophosphate （PF^-）, sulfate （SO^-） and chloride （Cl^-） were synthesized by usual neutralization of acids and bases at room temperature and characterized by IR, ^1H NMR and elemental analysis （EA）. The results show that these compounds possess the characteristic of ionic liquids. In addition, four of them, DABF, DACl, DASO and DAPF, were efficient catalysts for esterication of acetic acid with C1-C6 alcohols and octanol.     

Accelerating the electron transfer of choline oxidase using ionic-liquid/NH2-MWCNTs nano-composite

A nano-composite consisting of amine functionalized multi-walled carbon nanotubes and a room temperature ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate) was prepared and used for modification of glassy carbon electrode. By immobilizing choline oxidase (ChOx) on the modified electrode, the enzyme direct electron transfer has been achieved. The modified electrode exhibited a pair of well-defined cyclic voltammetric peaks at a formal potential of ?0.395?V versus Ag/AgCl in 0.2?M phosphate buffer solution at pH 7.0. This peak was characteristic of ChOx-FAD/FADH₂ redox couple. The electrochemical parameters such as charge transfer coefficient (??) and apparent heterogeneous electron transfer rate constant (k _s) were estimated to be 0.36 and 2.74?s^?1, respectively. When the enzyme electrode was examined for the detection of choline, a relatively high sensitivity (2.59???A?mM^?1) was obtained. Under the optimized experimental conditions, choline was detected in the concentration range from 6.9?×?10^?3 to 6.7?×?10^?1?mM with a detection limit of 2.7???M. The peak currents of ChOx were reasonably stable and retained 90% of its initial current after a period of 2?months.     

Nucleophilic substitution inO-phenyldibenzofuranium and 10-phenylxanthonium cations

Reactions ofO-phenyldibenzofuranium tetrafluoroborate with nucleophiles (OH^?, NO₂ ^?, AcO^?) in aqueous media follow the S_NAr-mechanism and involve dehydroarenes. In DMSO, this salt smoothly reacts with NO₂ ^? and I^? with predominant opening of the furan ring. 10-Phenylxanthonium tetrafluoroborate readily arylates the NO₂ ^? ion in water (at the N and O atoms), mainly with predominant opening of the central ring, and is completely decomposed even with weak bases (NH₂OH, 2,4-dinitrophenylhydrazine). The Bayer—Villiger oxidation of this salt affords xanthone and 2-phenoxybenzoic acid.     

Translational diffusion coefficient of a nitroxide radical in an ionic liquid, as determined via EPR spectroscopy, cyclic voltammetry, and chronoammetry

Values of the translational diffusion coefficient of a spin probe (2,2,6,6-tetramethyl-4-oxypiperidine-1-oxyl) are determined via cyclic voltammetry, chronoammetry, and EPR in ionic liquid (1-butyl-3methylimidazolium tetrafluoroborate) at 295 K. They are found to be (8 ± 3) × 10^?12, (9 ± 3) × 10^?12, and (11 ± 4) × 10^?12 m²/s, respectively.     

The Direct Electron Transfer of Iron‐Containing Superoxide Dismutase (Fe‐SOD) and its Catalysis for the Oxygen Reduction Reaction (ORR) in Room Temperature Ionic Liquids (RTILs) on a Gold Electrode

In this work, for the first time, the direct electron transfer of iron‐containing superoxide dismutase (Fe‐SOD) was observed by cyclic voltammetry on a gold (Au) electrode in three RTILs, i.e., 1‐ethyl‐3‐methylimidazolium tetrafluoroborate (EMIBF₄), 1‐n‐propyl‐3‐methylimidazolium tetrafluoroborate (PMIBF₄) and 1‐n‐butyl‐3‐methylimidazolium tetrafluoroborate (BMIBF₄). And the results demonstrate that when the scan rate was as low as 1 mV/s, a pair of well‐defined quasi‐reversible peaks of Fe‐SOD was presented, while as the potential scan rate was above 10 mV/s, the reduction peak of Fe‐SOD disappeared though its oxidation peak could be clearly observed even as the potential scan rate was up to 400 mV/s, strongly indicating that these CVs we observed were attributable to Fe‐SOD rather than the impurities in RTILs. Its catalysis for oxygen reduction reaction (ORR) was directly verified by the shifting of formal potential, E⁰′, of ORR, to the positive direction though the value of standard rate constant, κ⁰, corresponding to ORR, was not much enhanced. In PMIBF₄, for the multi‐walled carbon nanotubes (MWCNTs)‐modified gold electrode, both the reduction peak current and oxidation peak current for oxygen redox reaction were all dramatically enhanced compared to the case of a bare gold electrode, and the value of κ⁰ was also increased from 3.1 × 10^?3 cm s^?1 for the bare gold electrode, to 17.5 × 10^?3 cm s^?1. Hence, in the presence of Fe‐SOD in RTILs, MWCNTs, showing catalysis for the electron transfer process of ORR, coupled with Fe‐SOD, leading to the shifting of formal potential corresponding to ORR to the positive direction, presented us a satisfactory catalysis for ORR in RTILs. Some reasons available for this catalysis behavior stemming from Fe‐SOD, and MWCNTs as well, for ORR are discussed based on the previously developed proposition.     

Synthesis and characterization of anhydrous conducting polyimide/ionic liquid complex membranes via a new route for high‐temperature fuel cells

The paper deals with the synthesis and characterization of a new series of anhydrous conducting acid‐doped complex membranes based on polyimide (PI) and ionic liquid (IL) for high‐temperature fuel cells via a new route. For this purpose, three imidazolium‐based ILs (RIm⁺BF₄^?) with different alkyl chain lengths (R=methyl, ethyl, and butyl) are added into polyamic acid (PAA) intermediate prepared from the reaction of benzophenonetetracarboxylic dianhydride and diaminodiphenylsulfone in different –COOH/imidazolium molar ratios (n = 0.5, 1, and 2). Then, the thermally imidized complex membrane was doped with H₂SO₄. The conductivities of acid‐doped PI/IL complex membranes prepared by taking n of 1 are found to be in the range of 10^?4?10^?5 S cm^?1 at 180°C, whereas the acid‐free PI/IL complex membranes show the conductivity at around 10^?9?10^?10 S cm^?1. Thermogravimetric analysis results reveal that the acid‐doped PI/IL complex membranes are thermally stable up to 250°C. Dynamic mechanical analysis results of the acid‐doped ionically interacted complex membrane show that the mechanical strengths of the PI/IL complex membranes including 1‐methyl imidazolium tetrafluoroborate (MeIm‐BF₄) and 1‐ethyl 3‐methyl imidazolium tetrafluoroborate (EtIm‐BF₄) are comparable with those of pristine PI until 200°C. Furthermore, it can be clearly emphasized that the ionic interaction between carboxylic acid groups of PAA's and IL's cations offers a positive role in long‐term conductivity stability by preventing the IL migration at high temperatures. On the other hand, preliminary methanol permeability tests of the acid‐doped membranes show that they can also be considered as an alternative for direct methanol fuel cells. Copyright © 2011 John Wiley & Sons, Ltd.     

A Novel Sulfate Polymeric Membrane Sensor Based on a New Bis‐Pyrylium Derivative

A novel ion‐selective polymeric membrane sensor based on pyrylium‐4,4‐(1,4‐phenylen) bis[2,6‐bis(2‐naphthyl)]‐bis[tetrafluoroborate] (PBGNB) as an excellent sensing material is successfully developed. The electrode possesses the advantages of a very low detection limit (5.0×10^?8 M), a wide working concentration range (1.0×10^?8?1.0×10^?1 M) and specially, a high sulfate selectivity over most common organic and inorganic anions. The sensor displays Nernstian behavior (slope of 29.5±0.5 mV per decade) in a wide pH range (3.0–8.5). It shows a short response time in the whole concentration range (ca. 10 s). The electrode was used as an indicator electrode in the potentiometric titration of sulfate ions with barium ions. The proposed sensor was successfully applied to the direct determination of salbutamol sulfate and paromomycin sulfate.     

Physical and electrochemical characterization of activated carbons with high mesoporous ratio for supercapacitors based on ionic liquid as the electrolyte

A series of activated carbons with high mesoporous ratio were prepared by KOH reactivation based on activated carbon as the precursor. As the KOH/AC mass ratio was increased to 4:1, the mesoporous ratio increases from 60% to 76%, and the average pore size from 2.23 to 3.14?nm. Moreover, the specific capacitance for the activated carbon in ionic liquid 1-ethyl-3-methylmidazolium tetrafluoroborate ([EMIm]BF₄) can reach the maximum value of 189?F?g^?1 (8.0???F?cm^?2). In addition, the decrease of specific capacitance for activated carbons by KOH reactivation with current density increase shows two regimes, suggesting that activated carbons with high mesoporous ratio are much fit for charge?Cdischarge at larger current density.     

Boron-incorporated Sulfonated polysulfone/polyphosphoric acid electrolytes for supercapacitor application

In the present work, boron-doped multicomponent gel polymer electrolytes composed of host polymer, sulfonated polysulfone (SPSU) and the additives; ionic liquid, 1-ethyl-3-methyl-imidazolium tetrafluoroborate (IL), H₃BO₃, polyphosphoric acid (PPA) were prepared. Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) techniques were used to characterize the sulfonated polysulfone-based electrolytes. Ion conductivity of these gel electrolytes were studied by dielectric impedance analyzer within the temperature from ?20 to 100°C. The ionic conductivity of the SPSU-5IL-1PPA and SPSU-5IL-1H₃BO₃-1PPA were measured as 4.8 × 10^?3 and 9 × 10^?4 S cm^?1, respectively. Supercapacitor having activated carbon-based composite electrode and electrolyte was constructed with the configuration: Al/C/electrolyte/C/Al. The electrochemical properties and ion transfer characteristics of the supercapacitor were investigated by the cyclic voltammetry (CV). Galvanostatic charge—discharge experiments exhibited good electrochemical reversibility and produced a specific capacitance value of 120 F g^?1 at 1 A g^?1. The symmetric supercapacitor system was retained almost 85% of its initial activity after 1000 cycle.     

Vibrational Spectroscopic Study on Ion Solvation and Ion Association of Lithium Tetrafluoroborate in 4‐Ethoxymethyl‐ethylene Carbonate

应用红外及拉曼光谱研究了不同浓度的四氟硼酸锂在4-乙氧甲基-碳酸乙烯酯溶剂中的离子溶剂化和离子缔合现象。环形变谱带和羰基伸缩振动谱带的分裂,以及骨架环振动谱带的迁移和分裂表明,锂离子与溶剂分子间存在着较强的相互作用,这种相互作用是通过溶剂羰基氧原子实现的。利用光谱拟合技术定量计算了表观溶剂化数。随着电解质锂盐浓度的增加,溶剂化数逐渐由4.32降至1.26。此外,四氟硼酸根v1谱带的分裂表明在高浓度溶液中存在着光谱自由的四氟硼酸根、直接接触离子对和离子对二聚体。     

Heck Reaction of Iodoarenes with Methyl Acrylate Catalyzed by Cyciopalladated Complexes of Tertiary Arylamines Immobilized in Ionic Liquid[ Bmim ] ^＋ BF4^-

Heck reaction of iodoarenes with methyl acrylate, catalyzed by cyclolmlladated complexes of tertiary arylamines, was investi-gated in ionic liquid 1-butyl-3-metylimidazolium tetratluorobo-rate ([Bmim] BF4^- ). The products can be isolated convenient-ly from the ionic liquid-catalyst system. The catalysts could be reused for more than 10 times still with satisfactory catalytic ac-tivity.     

Differential Pulse Polarographic Determination of Some (5-Nitro-2-Furl)Alkylidene-2-Hydrazinothiazole Derivatives

Abstract

The differential pulse polarographic analysis of four (5-nitro-2-furyl)alkylidene-2-hydrazinothiazole derivatives are presented, 0.1 M tetramethylammonium tetrafluoroborate solution was found to be the best supporting electrolyte. At static mercury drop electrode the nitro group of the compounds studied was reduced to the amine in a six-electron process. Linear response was observed over 0.2 to 140 mg.L^?1 with a relative standard deviation of 3.3%.     

Cu(II) complexes of N-propyl-2-picolinamine N-oxide

Cu(II) complexes have been prepared with N-propyl-2-picolinamine N-oxide(PA) employing the perchlorate, tetrafluoroborate, nitrate, chloride and bromide salts. The following unique solids have been isolated and characterized: Cu(PA)₂X₂ (X = ClO₄^?, BF₄^? and NO₃^?) and Cu(PA)X₂ (X = Cl^?, Br^?). Characterization has been accomplished primarily by IR, electronic and ESR measurements of the solid state since considerable alteration of the complexes occurs on dissolution. PA bonds as a bidentate ligand via its N-oxide oxygen and amine nitrogen in all of the complexes. Anion coordination occurs in the halogen complexes and the nitrate ions appear to be bound to Cu(II) as monodentate ligands in Cu(PA)₂(NO₃)₂. In addition, there appears to be a rhombic distortion of the CuO₂N₂ chromophore of the perchlorate and tetrafluoroborate solids which is probably due to the steric requirements of the propyl substituents.     

Antitumor effects of binuclear ferrocene derivatives

On the basis of an earlier model of chemical carcinogenesis, the antitumor activity of the mono-, bi- and poly-nuclear ferrocene derivatives ferricenium tri-iodide (1), ferricenium tetrachloroferrate (2), 1, 1′-diethylferricenium triiodide: (3), N-(ferrocenylmethyl)hexamethylenetetramine tetrafluoroborate (4), bis(ferrocenylmethyl)benzotriazolium tetrafluoroborate (5), bis(ferrocenyl-α-ethyl)benzotriazolium tetrafluoroborate (6) and bis(ferrocenylmethyl)-2-methylbenzimidazolium tetrafluoroborate (7), and the oligomer (—Fc—CH₂—Fc^+˙—CH₂—)_7–8^? (PF₆)_7–8 (8) was studied in vivo (Fc?C₁₀H₈Fe). The tumor models studied included MCH-11 (mouse sarcoma induced by methylcholantrene), P-815 (mouse mastocytoma of DBA/2 origin) and virus-induced Raucher leukemia (RLV). The cytotoxic effects of these preparations were examined against in vitro cultured normal murine cells (line L-929). The binuclear ferrocene derivatives 5, 6 and 7 inhibited the development of experimental tumors in mice. Ferricenium tri-iodide (1) was effective in Rauscher leukemia. Kinetic dependencies for most complexes had a two-phase character: the region of inhibition of tumorogenesis was followed by a region in which the complexes accelerated the development of this process. The link between the structure of compounds 1–8 and their antitumor effects is discussed.     

ULTRASONIC RELAXATION KINETICS OF PLANAR:OCTAHEDRAL EQUILIBRIA OF A NICKEL MACROCYCLIC COMPLEX

Abstract

The equilibrium between the diamagnetic, planar nickel(II) macrocyclic complex known as NiCR²⁺(CR is 2,12-dimethyl-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17),2, 11,13,15pentaene) and its paramagnetic, six-coordinate dimethanol adduct has been examined in methanol solution as the tetrafluoroborate salt. From the temperature dependence of the electronic absorption spectrum, thermodynamic parameters of ΔH°₄₆ = ?4.35 kcal mol^?1 and ΔS°₄₆ = ?8.72 cal deg^?1 mol^?1 were determined. From the excess ultrasonic absorption a relaxation frequency of 15 MHz was observed from which rate constants of k₄₆ of 8.6 × 10⁷ s^?1 and k₆₄ of 7.9 × 10⁶ s^?1 were calculated. The rate constant k₄₆ is nearly the same as the rate constant for solvent exchange which had previously been determined by NMR. This implies that the solvent exchange is effected by the octahedral-planar equilibrium and that a two-step mechanism with a five-coordinate intermediate can be eliminated.     

CALORIMETRIC STUDY OF THERMOCHROMIC COMPLEXES. 2. HEAT CAPACITY AND PHASE TRANSITION OF BIS(N,N‐DIETHYLETHYLENEDIAMINE)COPPER(II) PERCHLORATE

Abstract

The thermochromic phase transition of bis(N,N-diethylethylenediamine) copper(II) perchlorate has been studied by adiabatic calorimetry in the 12–359 K temperature range. A large heat capacity anomaly was observed at 317.64 K with a long heat-capacity tail extending down to ～200 K. The enthalpy and entropy of the phase transition were found to be δ_trs H = 17.43 kJ mol^?1 and δ_trs S = 55.21 J K^?1 mol^?1, respectively. Together with a calorimetric study of a homologous thermochromic complex, bis(N,N-diethylethylenediamine)copper(II) tetrafluoroborate (J. Phys. Chem. Solids, 55, 99 (1994)), the nature of the present thermochromic phase transition is well described by a puckering motion of the copper-ligand chelate rings and a change in the ligand-field strength estimated on the basis of the angular overlap model. The correlation between structures, electronic spectra and thermal properties is discussed.