1-己基-3-甲基咪唑六氟磷酸盐离子液体的微波辅助合成与结构表征

采用1-溴代己烷和N-甲基咪唑为原料,微波辅助快速合成了溴化1-己基-3-甲基咪唑([HMIM]Br)中间体,此步反应产率可达到95%。通过将中间体和六氟磷酸钾进行离子交换,制备了离子液体1-己基-3-甲基咪唑六氟磷酸盐([HMIM]PF6),产率约为48%。与传统方法相比,反应时间极大地缩短。产物的结构经傅立叶变换红外光谱(FT-IR)、超导脉冲傅立叶变换核磁共振氢谱(1HNMR)和超导脉冲傅立叶变换核磁共振碳谱(13CNMR)确认,纯度经高效液相色谱法(HPLC)分析达到99.0%以上。     

Experimental vibrational study of imidazolium-based ionic liquids: Raman and infrared spectra of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide and 1-ethyl-3-methylimidazolium ethylsulfate

The vibrational structure of two room-temperature ionic liquids with the cation 1-ethyl-3-methylimidazolium [EMIM] and the respective anions bis(trifluoromethylsulfonyl)imide [TFSI] and ethylsulfate [EtOSO(3)] is investigated. In particular, attenuated total reflection (ATR) infrared (IR) as well as Raman spectra in the spectral range from 500 to 3500 cm(-1) have been recorded and analyzed. Moreover, the depolarization ratios of the Raman lines are determined. The individual peaks are assigned to the corresponding vibrational modes of the molecules. While the CH stretching region around 3000 cm(-1) is dominating in Raman spectra, it is remarkably weak in IR spectra. Finally, the results for 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide are compared to previous studies of single ions available in the literature. This comparison shows good agreement.     

Facile ultrasound-assisted synthesis of ZnO nanorods in an ionic liquid

ZnO nanocrystals have been synthesized by ultrasound-assisted synthesis from Zn(CH₃COO)₂2H₂O and NaOH in the neat room-temperature ionic-liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide, [C₄mim][Tf₂N]. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) show that the formed ZnO nanocrystals are of rod like shape with lengths from 50 to 100 nm and diameters of about 20 nm. X-ray diffraction (XRD) confirms the crystallinity as well as the sample purity. The band gap of the as-prepared ZnO nanorods was estimated to be 3.31 eV from UV–Vis absorption measurements. The photoluminescence spectrum shows the characteristic greenish emission of ZnO at room temperature (λ_max = 563 nm). The ZnO bonding levels have been determined by X-ray photoelectron spectroscopy (XPS). Nitrogen adsorption–desorption measurements show typical samples to have a specific surface area of 49.93 m²/g.     

Degradation of 1-butyl-3-methylimidazolium chloride ionic liquid in a Fenton-like system

The study examined the usefulness of a Fenton-like system for the degradation of ionic liquid residues in water. The ionic liquid was oxidized in a dilute aqueous solution of 1-butyl-3-methylimidazolium chloride (bmimCl). The ionic liquid decomposes readily and rapidly in aqueous solution by chemical degradation in a Fenton-like system. Under chosen conditions the initial bmimCl solution was reduced by a factor of 0.973 within 90 min. Additional results showed that bmimCl degradations in a Fenton-like system in excess H2O2 could be interpreted as a combined oxidation-reduction mechanism. Preliminary investigations of the mechanism of such degradations have indicated that initial OH* radicals can attack any one of the three carbon atoms on the imidazolium ring. The intermediates of this reaction may be mono- di- or amino- carboxylic acids.     

Facile synthesis of ZnO nanostructures and investigation of structural and optical properties

ZnO nanostructures were synthesized by chemical bath deposition method, using zinc nitrate [Zn(NO₃)₂] and hexa-methylene-tetra-amine [(HMT),C(H₂)₆N₄] as precursors. Controlled size and shape evolution of ZnO nanostructures were achieved by changing the HMT concentration from 0.025 M to 0.1 M, whereas Zn(NO₃)₂ concentration kept constant. X-ray diffraction (XRD) and Raman study confirmed the formation of single crystalline, hexagonal wurtzite ZnO structure. Sharp peaks in Raman spectra, corresponding to E₂(low) and E₂(high) referred to wurtzite structure with higher order of crystallinity. Transmission electron microscopy (TEM) revealed that the shape and size of the nanostructures reduced, with increasing concentration of HMT. Further, effect of structure's size was observed in the band gap (shift). Photoluminescence study showed two peaks at ~ 380 nm and ~ 540 nm corresponding to the band to band transition and defect transitions. Modifications of properties are explained in detail on the basis of shape and size change of the structures and possible mechanism is discussed.     

Facile synthesis of Pr(OH)3 nanostructures and their application in water treatment

By means of a facile electrochemical approach, Pr(OH)₃ nanostructures consisting of nanosheets amorphous were successfully constructed on Cu substrates, and their morphologies can be readily tuned by simply adjusting the current density. Moreover, these Pr(OH)₃ nanostructures exhibit a good performance to remove Congo red in wastewater treatment.     

Influence of 1-ethyl-3-methylimidazolium bis (trifluoromethyl sulfonyl) imide plasticization on zinc-ion conducting PEO/PVdF blend gel polymer electrolyte

The influence in terms of plasticizer on zinc-ion conducting polymer blend electrolyte system, [PEO (90 wt%)/PVdF (10 wt%)]-15 wt% Zn (CF₃SO₃)₂] with various concentrations of 1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide (EMIMTFSI) was investigated. The freshly-prepared thin films of [PEO (90 wt%)/PVdF (10 wt%)]-15 wt% Zn (CF₃SO₃)₂)?+?x wt% EMIMTFSI, where x?=?1, 3, 5, 7, and 10 wt%] were characterized by means of X-ray diffraction (XRD), Fourier transformed infrared (FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and impedance analysis techniques. The room temperature XRD patterns tend to support the enhanced amorphous phase as a result of deducing the degree of crystallinity of the polymer blend–salt system by the addition of 7 wt% EMIMTFSI. The relevant SEM images of 7 wt% EMIMTFSI incorporated gel polymer electrolyte exhibit a minimised spheurilite structure when compared to that of the polymer blend–salt system. Unusually, the highest ionic conductivity realized in the case of the typical gel polymer electrolyte system, [PEO/PVdF-Zn (CF₃SO₃)₂ + 7 wt% EMIMTFSI] is found to be 1.63?×?10^?4 S cm^?1 at room temperature. The temperature dependence of conductivity has been examined based on the Vogel–Tammann–Fulcher (VTF) equation, thereby suggesting the segmental chain motion and free volume changes. The occurrence of ion dynamics and dielectric relaxation behaviour in the chosen system has been analysed in a detailed fashion at room temperature using frequency response impedance formalisms involving electric modulus and dielectric permittivity features.     

Gold particle synthesis via reduction of gold salt in the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate aqueous solution

The formation of gold particles via reduction of HAuCl4 x 4H2O by ascorbic acid in the presence of ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate and sodium alginate has been studied. The shape of the synthesized particles could be tuned by controlling the reaction conditions. Specifically, the flowerlike gold particles can be synthesized by the present synthetic route. It demonstrates that both the ionic liquid and the sodium alginate play an important role for the formation of the flowerlike particles. The synthesized flowerlike particles show enhanced electroactivity for H2O2.     

Sonochemical preparation of TiO2 nanoparticles in the ionic liquid 1-(3-hydroxypropyl)-3-methylimidazolium-bis(trifluoromethylsulfonyl)amide

Spherical shaped anatase nanoparticles (ø 5 nm) have been synthesized in the ionic liquid 1-(3-hydroxypropyl)-3-methylimidazolium-bis(trifluoromethanesulfonyl)amide from titanium tetraisopropoxide by ultrasound assisted synthesis under ambient conditions. XRD, EDX, TEM, XPS, Raman, UV–vis, PL and BET measurements have been employed for characterization of the nanostructure of as-prepared TiO₂. XRD and Raman measurements both show that the obtained material is crystalline with anatase structure. The morphology of TiO₂ nanoparticles was characterized by transmission electron microscopy (TEM). The bandgap of the TiO₂ nanocrystals estimated from XRD and UV–vis measurements is about 3.3 eV. The surface area of a typical sample is 177 m² g⁻¹. The synthesized anatase nanocrystals show good photocatalytic activity in the degradation of methylorange.     

Electrodeposition and properties of nanocrystalline ZnO films prepared in the presence of anionic surfactant SDS and ionic liquid 1-butyl-3-methylimidazolium methylsulfate

ZnO thin films were potentiostatically electrodeposited on transparent tin oxide conducting glass substrates at ?1.0 V (vs. Ag/AgCl) in the presence of anionic surfactant, sodium dodecyl sulphate (SDS) and hydrophobic ionic liquid, 1-butyl-3-methylimidazolium methylsulfate [bmim][CH₃SO₄]. X-ray diffraction (XRD) investigation confirm the formation of nanocrystalline and stoichiometric ZnO thin films. Scanning electron microscopy (SEM) results reveal that the grain size of the deposited ZnO film is reduced from 85 to 28 nm when small amount of ionic liquid is added to the deposition bath. Photoluminescence study at room temperature shows a clear absorption edge in the ultra violet (UV) region confirming the high quality, nanocrystalline and stoichiometric nature of the deposited ZnO films.     

Crystal structure and aggregation behavior in water of ionic liquid 1-hexadecyl-3-methylimidazolium Bromide

A large-transparent single crystal of 1-hexadecyl-3-methylimidazolium bromide monohydrate ([C₁₆mim]Br·H₂O) with 4-mm length was firstly obtained in the water-trichloromethane-toluene growth system (V_water:V_{trichloromethane}:V_toluene = 0.1:1:2). The crystal structure was determined by single crystal X-ray diffraction method. It crystallizes in the triclinic system, space group P-1, with unit cell parameters a = 5.4962(15) Å, b = 7.839(2) Å, c = 27.279(8) Å, α = 94.375°(4), β = 91.500°(5), γ = 101.999°(4), Z = 2, V = 1145.2(5)ų, Dc = 1.176 Mg/m³, μ = 1.804 mm^− 1, F(000) = 436, the final R1 = 0.0497, wR2 = 0.1154. The 3D supramolecular structure is constructed through the weak interactions between imidazolium cations, Br⁻ anions and lattice water molecules. The long alkyl chain to imidazolium ring and lattice water molecules play an important role in the self-assembled process. Moreover, it is proposed that [C₁₆mim]Br has the aggregation behavior in water at the higher concentration and the possible self-assembled structure is the interdigitated pattern.     

Ultrasound-assisted synthesis of dentritic ZnO nanostructure in ionic liquid

A facile and environment-friendly sonochemical route to fabricate well-defined dentritic ZnO nanostructures in a room-temperature ionic liquid has been reported. The structure and morphology of the synthetic branch-shaped ZnO products were characterized by X-ray diffraction and transmission electron microscopy. The photoluminescence (PL) spectrum of the synthetic dentritic ZnO nanostructures exhibits a strong ultraviolet emission at 378 nm and a weak green emission at 532 nm respectively at room temperature. A plausible formation mechanism of dentritic ZnO nanostructures was discussed in detail.     

Facile synthesis of superparamagnetic Fe-doped ZnO nanoparticles in liquid polyols

A facile polyol process was established to prepare superparamagnetic Fe-doped ZnO nanoparticles in a liquid polyol using Fe(acac)₃ and Zn(acac)₂ as precursors and triethylene glycol as the solvent. Scanning electron microscopy (SEM) images showed that as-prepared nanoparticles are uniform in size. X-ray diffraction (XRD) analysis revealed that the nanoparticles are of wurtzite structure without an impure phase. The successful doping of the Fe element into the ZnO host was evident by XRD lines shifting and energy dispersive X-ray spectroscopy (EDS) results. Magnetization measurements demonstrated that the Fe-doped ZnO nanoparticles were superparamagnetic at room temperature.     

All-cellulose composites by partial dissolution in the ionic liquid 1-butyl-3-methylimidazolium chloride

Fully bio-based and biodegradable all-cellulose composites were prepared in the form of films by partial dissolution of two cellulose sources: a commercially available microfibrillated cellulose (MFC) and filter paper (FP). The solvent selected for this work was the ionic liquid 1-butyl-3-methylimidazolium chloride ([C₄mim]Cl). Both cellulose sources were partially dissolved at 80 °C and consolidated by partial dissolution, resulting in excellent mechanical properties. X-ray diffraction and electron microscopy demonstrated that partial dissolution was a viable path to transform FP into a continuous paracrystalline matrix reinforced with cellulose I crystallites. In contrast, partially dissolved MFC was not as thoroughly dissolved and large amounts of undissolved material were still visible along the centre line of the films after the longest dissolution times. Consequently, partially dissolved MFC retained its initially high crystallinity. The degree of polymerization of the materials after dissolution was significantly reduced.     

Preparation of PbS-type PbO nanocrystals in a room-temperature ionic liquid

In a strong polar environment of ionic liquid 1-n-butyl-3-ethylimidazolium tetrafluoroborate [BEIM]BF₄, PbO nanocrystals with PbS-type crystal structure were successfully synthesized by the thermal decomposition of Pb(OH)₂ at 180 °C for 3 h under ambient pressure. The product was characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), electric diffraction (ED), X-ray photoelectron spectrum (XPS) and elemental analysis.     

Thermodynamic Properties at Saturation Derived from Experimental Two-Phase Isochoric Heat Capacity of 1-Hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide

New measurements are reported for the isochoric heat capacity of the ionic liquid substance 1-hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C6mim][NTf2]). These measurements extend the ranges of our earlier study (Polikhronidi et al. in Phys Chem Liq 52:657, 2014) by 5 % of the compressed liquid density and by 75 K. An adiabatic calorimeter was used to measure one-phase \((C_{\mathrm{V1}})\) liquid and two-phase \((C_{\mathrm{V2}})\) liquid + vapor isochoric heat capacities, densities \((\rho _s)\), and phase-transition temperatures \((T_s)\) of the ionic liquid (IL) substance. The combined expanded uncertainty of the density \(\rho \) and isochoric heat capacity \(C_\mathrm{V}\) measurements at the 95 % confidence level with a coverage factor of \(k = 2\) is estimated to be 0.15 % and 3 %, respectively. Measurements are concentrated in the immediate vicinity of the liquid + vapor phase-transition curve, in order to closely observe phase transitions. The present measurements and those of our earlier study are analyzed together and are presented in terms of thermodynamic properties \((T_s\), \(\rho _s\), \(C_{\mathrm{V1}}\) and \(C_{\mathrm{V2}})\) evaluated at saturation and in terms of key-derived thermodynamic properties \(C_\mathrm{P}\), \(C_\mathrm{S}\), \(W_\mathrm{S}^{{\prime }}\), \(K_{\mathrm{TS}}^{{\prime }}\), \(\left( {\partial P/\partial T} \right) _{\mathrm{V}}^{\prime }\), and \(\left( {\partial V/\partial T} \right) _\mathbf{P}^{\prime })\) on the liquid + vapor phase-transition curve. A thermodynamic relation by Yang and Yang is used to confirm the internal consistency of measured two-phase heat capacities \(C_{\mathrm{V2}} \), which are observed to fall perfectly on a line as a function of specific volume at a constant temperature. The observed linear behavior is exploited to evaluate contributions to the quantity \(C_{\mathrm{V2}} = f(V, T)\) from chemical potential \(C_{{\mathrm{V}\upmu }} =-T\frac{\mathrm{d}^{{2}}\mu }{\mathrm{d}T^{2}}\) and from vapor pressure \(C_{\mathrm{VP}} =VT\frac{\mathrm{d}^{2}P_{\mathrm{S}} }{\mathrm{d}T^{2}}\). The physical nature and specific details of the temperature and specific volume dependence of the two-phase isochoric heat capacity and some features of the other derived thermodynamic properties of IL at liquid saturation curve are considered in detail.     

Sol-gel synthesis of alumina,titania and mixed alumina/titania in the ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulphonyl) amide

In this paper we report on the synthesis of alumina, titania and mixed alumina–titania in the ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulphonyl) amide [Py_1,4]TFSA via sol-gel methods using aluminium isopropoxide and titanium isopropoxide as precursors. Our results show that the as-synthesized alumina is mainly mesoporous boehmite with an average pore diameter of 3.8 nm. The obtained boehmite is subject to a phase transformation into γ-Al₂O₃ and δ-Al₂O₃ after calcinations at 800 and 1,000 °C, respectively. The as-synthesized TiO₂ shows amorphous behaviour and calcination at 400 °C yields anatase which undergoes a further transformation to rutile at 800 °C. The as-prepared alumina–titania powders are amorphous and transformed to rutile and α-Al₂O₃ after calcination at 1,000 °C TiO₂. The obtained alumina–titania has a higher surface area than those of alumina or titania. The surface area of the as-synthesized alumina–titania was found to exceed 486 m² g⁻¹, whereas the surface areas of the as-synthesized boehmite and titania were around 100 m² g⁻¹, respectively.     

Facile synthesis of ZnO nanorod arrays and hierarchical nanostructures for photocatalysis and gas sensor applications

A facile one-step hydrothermal route was demonstrated to grow ZnO nanorod arrays and hierarchical nanostructures on arbitrary substrates without any catalysts and seeds coated before the reaction, which are prerequisite in the current two-step protocol. Meanwhile, ZnO nanoflowers composed of nanorods were obtained at the bottom of the autoclaves in the absence of substrates. An in situ spontaneous-seeds-assisted growth mechanism was tentatively proposed on the basis of the experimental data to explain the growth process of ZnO nanostructures. Moreover, the obtained ZnO nanorod arrays exhibited superior photocatalytic activity for decomposing methyl orange, and the nanoflowers showed better gas sensing performance towards some flammable gases and corrosive vapors with high sensitivity, rapid response-recovery characteristics, good selectivity and long-term stability.     

Direct extraction of double-stranded DNA into ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate and its quantification

Ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (BmimPF6), as a green solvent, was successfully used for the direct extraction of dsDNA. The extraction efficiency and the distribution coefficient values indicated that trace amounts of DNA at the levels of <5 ng microL-1 facilitate quantitative fast extraction, while proteins and metal species do not interfere. A total of 30% of the DNA in ionic liquid at approximately 20 ng microL-1 was back extracted into aqueous phase in phosphate-citrate buffer with a single-stage extraction. The extraction is demonstrated to be endothermic with an enthalpy of 34.3 kJ moL-1. The extraction mechanisms were proposed and verified by 31P NMR and FT-IR spectra. Interactions between cationic 1-butyl-3-methylimidazolium (Bmim+) and P-O bonds of phosphate groups in the DNA strands take place both in the dissolved BmimPF6 in aqueous phase and at the interface of the two phases. This interaction consequently led to the transformation of DNA conformations, along with a reduction of ethidium resonance light scattering at 510 nm, and a procedure for DNA quantification in ionic liquid was developed based on this observation.