1-butyl Pyridinium Research Articles

Refolding of guanidinium hydrochloride denatured bovine serum albumin using pyridinium based ionic liquids as artificial chaperons

Herein, the refolding ability of pyridinium based ionic liquids against chemically induced unfolding of bovine serum albumin (BSA) is reported. The study was performed utilizing circular dichroism (CD), steady-state fluorescence, time-resolved fluorescence, and dynamic light scattering (DLS) experiments. Further, ANS (8-Anilinonaphthalene-1-sulfonic acid) binding was performed to study the effect of ionic liquids (ILs) on the hydrophobicity of unfolded protein. The CD results confirmed that the alpha helical content of the denatured protein increased by a significant amount in presence of different concentrations of all the three ILs. The CD results were further supported by steady state fluorescence and ANS binding study. The dynamic light scattering (DLS) results show that the hydrodynamic size of the unfolded protein decreases in presence of all the three ILs. The decrease in hydrodynamic size may be attributed to the increase in compactness and the possible refolding of the protein in presence of ILs. Fluorescence lifetime measurements confirm that the average lifetime of GdmCl treated BSA reached near to the value of native BSA in presence of ILs which again supports the refolding of protein. All the experimental results agreed with each other and suggested that all three ILs have the potential to refold the denatured protein. The 1-butyl pyridinium bromide (BPB), however, proved to be the most effective refolding agent amongst the three ILs utilized for the study.

DETERMINATION OF PYRIDINIUM IONIC LIQUID CATIONS BY ION CHROMATOGRAPHY WITH DIRECT CONDUCTIVITY DETECTION

Determination of two pyridinium ionic liquid cations (1-ethyl pyridinium cation and 1-butyl pyridinium cation) by ion chromatography using a carboxylic acid based cation-exchange column and direct conductivity detection was carried out. The optimized chromatographic conditions were 8.0 m mol L−1 methanesulfonic acid +5% acetonitrile (v/v) as eluent, flow rate of 1.0 mL min−1, and column temperature of 45°C. Detection limits (S/N = 3) for the two cations were 1.93 and 4.68 mg L−1, respectively. Relative standard deviations (n = 5) for peak areas were less than 0.8%. This simple method was successfully applied to determine pyridinium ionic liquids in spiked surface water.

Dramatic Change in Viscosities of Pure Ionic Liquids upon Addition of Molecular Solvents

Viscosities of binary mixtures of pyridinium based ionic liquids (1-butyl pyridinium tetrafluoroborate, [BP][BF4], 1-butyl 3-methyl pyridinium tetrafluoroborate [3-MBP][BF4], 1-butyl 4-methyl pyridinium tetrafluoroborate, [4-MBP][BF4]), and phosphonium based ionic liquids, (tetrabutyl phosphonium alaninate, [TBP][Ala]; tetrabutyl phosphonium valinate, [TBP][Val]) with the molecular solvents, water, methanol and dichloromethane, have been measured at 298.15 K. A Brookfield ultra-rheometer was employed to measure the reported viscosities. The drop in viscosity in the close vicinity of pure ionic liquid is more prominent in polar solvents like water compared to less polar solvents. The temperature dependence of this observation was also studied for binary mixtures of [4-MBP][BF4] with water in range of 298.15–323.15 K. The Vogel-Fulcher-Tamman (VFT) equation was employed to investigate the temperature dependence of the viscosities of pure pyridinium-based ionic liquids in the temperature range from 298.15–323.15 K.

Direct electrochemistry of glucose oxidase based on its direct immobilization on carbon ionic liquid electrode and glucose sensing

Direct electrochemistry of glucose oxidase (GOx) has been achieved by its direct immobilization on carbon ionic liquid electrode (CILE) with a conductive hydrophobic ionic liquid, 1-butyl pyridinium hexafluophosphate ([BuPy][PF 6]) as binder for the first time. A pair of reversible peaks is exhibited on GOx/CILE by cyclic voltammetry. The peak-to-peak potential separation (Δ E P) of immobilized GOx is 0.056 V in 0.067 M phosphate buffer solution (pH 6.98) with scan rate of 0.1 V/s. The average surface coverage and the apparent Michaelis–Menten constant are 6.69 × 10 −11 mol·cm −2 and 2.47 μM. GOx/CILE shows excellent electrocatalytic activity towards glucose determination in the range of 0.1–800 μM with detection limit of 0.03 μM ( S/ N = 3). The biosensor has been successfully applied to the determination of glucose in human plasma with the average recoveries between 95.0% and 102.5% for three times determination. The direct electrochemistry of GOx on CILE is achieved without the help of any supporting film or any electron mediator. GOx/CILE is inexpensive, stable, repeatable and easy to be fabricated.

Microwave Assisted Dealkylation of Alkyl Aryl Ethers in Ionic Liquids.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Microwave Assisted Dealkylation of Alkyl Aryl Ethers in Ionic Liquids

Alkyl aryl ethers undergo selective dealkylation in 1-butyl pyridinium bromide and 1-butyl-3-methyl imidazolium bromide ionic liquids under microwave irradiation to give the corresponding phenols in high yields. The ionic liquids serve the dual purpose of solvent as well as reagent and allow easy isolation of products.