Imidazolium Hexafluorophosphate Research Articles

How to Control Excited‐State Prototropism of Photoacids via the Acidity of Ionic Liquids

AbstractTo control presence of ionic species in excited state of a fluorophore is quite challenging task. Herein, we report the unusual excited‐state prototropism of an important photoacid carbazole dissolved in water in presence of small amount of added ionic liquids (ILs). We have observed that the excited state prototropic equillibria of carbazole dissolved in water can be affected by the presence of small amount of added ILs. More importantly, the excited‐state prototropism of carbazole can be controlled via the acidity of added ILs. More specifically, we found that the fluorescence emission from the neutral prototropic form of carbazole can be observed even under highly basic conditions (aqueous NaOH, pH 12.6) in presence of only small amount of any of the added ILs such as 1‐butyl‐3‐methyl imidazolium tetrafluoroborate ([bmim][BF4]), 1‐butyl‐1‐methylpyrrolidinium bis(trifluromethansulphonyl)imide ([bmpyrr][Tf2N]) and 1‐butyl‐3‐methyl imidazolium hexafluorophosphate ([bmim][PF6]). The observed fluorescence emission from the neutral form of carbazole can be attributed to excited state protonation of carbazole anion by taking proton from IL cation. In a true sense, the excited state carbazole does not transfer the proton; rather takes the proton from IL cation. The observed unusual excited state protonation of carbazole anion to neutral carbazole, in the excited state even in highly basic conditions can be attributed to the presence of acidic protons with the IL cations. Herein, we reports quite unusual results where the IL assisted excited state protonation of carbazole anion occured in an exclusive manner in which proton from the IL cation exclusively protonate carbazole anion surrounded by highly alkaline media (water, pH 12.6). ILs acidity controlled excited‐state properties of important photoacids can have a wide range of chemical and biological applications and the observed results can play important roles in chemical technology to control prototropic equillibra with the help of ILs for some specific application. These observations can open new windows to attract more applications for these alternative solvent media to applications in pH and pOH jump experiments, effective photo protecting agents and chemical lasers.

Deep Oxidative Desulfurization Utilizing Hybrid Keggin Catalyst with 1-methyl-3-octyl imidazolium hexafluorophosphate

تعتبر إزالة الكبريت بالأكسدة العميقة موضوعًا مهمًا لأبحاث التحفيز البيئي لإنتاج الديزل منخفض الكبريت.أحد العوامل المساعدة التي تم استخدامها مؤخرًا لإزالة مركبات الكبريت المقاوم من نموذج الديزل بالاكسدة هو بولي أوكسوميتالات من نوع كيجن. في هذا العمل, تم اختبار العامل المساعد من نوع كيجن TBAPW11O39 , نموذج الديزل, بيروكسيد الهيدروجين(H2O2) وسائل ايوني من نوع OMIM(PF6)) تحت ظروف تفاعل مختلفة. تم التقاط مركب الكبريت ثنائي بنزوثيوفين (DBT) من نموذج الديزل في السائل الايوني (IL) ثم يتأكسد الى سلفون مع بيروكسيد الهيدروجين كمؤكسد باستخدام TBAPW11O39 في مفاعل نوع (batch) . تم دراسة تأثيرزمن(30-180 دقيقة) و درجة حرارة (T) التفاعل(343,3232,303 كلفن) و وزن العامل المساعد(0.5-6) غم / لتر و النسبة المولية O/S) H2O2/ DBT) من 1:1الى 1:5(مول/مول) والنسبة الحجمية IL/diesel (1/10 – 5/10) (مل/مل).أظهر العامل المساعدد فعالية عالية لإزالة DBT باستخدام بيروكسيد الهيدروجين ، وبلغت اعلى إزالة للكبريت بنسبة 96٪ في الظروف المثلى (10 مل من نموذج الديزل ، T = 343 K ، وزن العامل المساعد=3 غم / لتر، النسبة المولية المؤكسد/مركب الكبريتH2O2/DBT))=1:5 والنسبة الحجمية السائل الايوني/الديزل= 2/10 لمدة 120 دقيقة). تشير هذه النتائج إلى أن ازالة الكبريت بالأكسدة التحفيزية مع الاستخلاص باستخدام العامل المساعد كيجن الهجينة لنموذج وقود الديزل هي طريقة فعالة وتوفر وعدًا لتحقيق إزالة الكبريت بعمق كبير.

In-Situ-Generated Fluoride-Assisted Rapid Dissolution of Uranium Oxides by Ionic Liquids.

A quantitative, rapid, endothermic dissolution of U3O8 in C4mim·PF6 (1-alkyl-3-methyl imidazolium hexafluorophosphate) has been achieved within 2 h at 65 °C by in situ generated fluoride ions by pre-equilibrating the ionic liquid with suitable concentrations of nitric acid. The efficiency of the dissolution followed the trend: UO3 > UO2 > U3O8. The fluoride generation was found to increase with the concentration of nitric acid being equilibrated, the water content of the ionic liquid, and also the time of equilibration. The rate of dissolution of U3O8 followed the trend: C4mim·PF6> C6mim·PF6 > C8mim·PF6. The maximum loading observed for the present case was 200 mg mL-1 which is considered to be quite high with an ionic liquid. The effects of different acid pre-equilibration (HClO4, HCl) on F- generation and subsequent dissolution characteristics have also been investigated. The in situ F- generation, as well as U3O8 dissolution, were found to predominantly follow a pseudo-second-order rate kinetics, while the rate constants for U3O8 dissolution were found to be higher than that of F- generation. The dissolved uranium was successfully electrodeposited on a Cu plate, as confirmed by EDXRF, while the formation of UO2 was revealed from the XRD pattern of the deposit.

The Impact of Chemical Modifications on The Ionic Conductivity of Ionic Liquid Encapsulated in Carbon Nanotubes, Potential Application in Aluminum Ion Battery

The transport and thermodynamic properties of 1-ethyl-3methyl imidazolium hexafluorophosphate ([EMIM][PF6]) ionic liquid encapsulated in carbon nanotubes or graphite represent a significant challenge in the development of Aluminum-ion batteries. To achieve high energy density in Aluminum-ion batteries, it is explored the use of ionic liquid solvents as electrolytes to enhance the ionic conductivity of the ionic liquid when encapsulated in carbon nanotubes as electrodes. The doping effects of sulfur and boron atoms in single-walled carbon nanotubes (SWCNTs) have been investigated to determine their impact on the ionic transfer number of the ionic liquid encapsulated in SWCNTs. The Green-Kubo formalism has been employed to calculate the ionic transfer number and electrical conductivity of the ionic liquid when encapsulated in SWCNTs doped with sulfur and boron atoms. The results obtained using the Green-Kubo formalism indicate that sulfur doping in SWCNTs, particularly in those with a larger radius, serves as a selective porous electrode material, significantly enhancing the electrical conductivity of the confined ionic liquid. Furthermore, the radial distribution function between the carbon alkyl groups in the ionic liquid and the carbon wall of the carbon nanotube, which is doped with sulfur and boron atoms, demonstrates that the doping effect does not alter the radial distribution function. The Green-Kubo result obtained for the electrical conductivity of the ([EMIM][PF6]) ionic liquid demonstrates excellent agreement with the experimental data.

Cheap and efficient strategy for photocatalytic degradation of ionic liquids by La/Ce-codoped TiO2@PAM composites.

Ionic liquids are regarded as green solvents mainly due to their non-volatile and easy regeneration and recycling properties. However, ionic liquids have negative effects on the environment and human health, especially alkyl imidazole ionic liquids are more toxic than traditional organic solutions. Studies on the toxicology, ecotoxicology, and degradation of ionic liquids are rarely found in the literature. Here, we prepared the cheap La and Ce-codoped TiO2@PAM (polyacrylamide) composite microspheres with a simple procedure for the first time to degrade three kinds of imidazole ionic liquids with high efficiency. The experimental results show that the composite La (0.25%) and Ce (0.15%)-codoped TiO2@PAM composite microspheres with calcination temperature of 450 °C had a high photocatalytic activity for 1-butyl-3-methyl imidazolium hexafluorophosphate, 1-hexyl-3-methyl imidazolium hexafluorophosphate, and 1-octyl-3-methyl imidazolium hexafluorophosphate with the concentration of 10 mg/L. The photocatalysis degradation extent of the three ionic liquids is 97.4, 91.2, and 88.5% at 90 min. This work opened a new route for the simple preparation of cheap composite microspheres in the photocatalytic degradation of ionic liquids with a high efficiency.

Diazo-Transfer Reaction of Nonactivated Ketones with 2-Azido-1,3-bis(2,6-diisopropylphenyl)imidazolium Hexafluorophosphate (IPrAP).

The diazo-transfer reaction of nonactivated ketone under mild reaction conditions was developed. Various nonactivated ketones such as aryl methyl ketones, sec-alkyl methyl ketones, and cyclic ketones were transformed into their corresponding α-diazoketones in one step by treating 2-azido-1,3-bis(2,6-diisopropylphenyl)imidazolium hexafluorophosphate (IPrAP) in the presence of iPr2NH in ethylene glycol. In the reaction of IPrAP with prim-alkyl methyl ketone and prim-alkyl aryl ketones, migratory amidation proceeded under the reaction conditions to afford the corresponding amides.

Imidazolium ionic liquids as neat lubricant for electroplating Sn on Cu substrate under sliding electrical contact at high temperatures up to 80 °C

Three kinds of imidazolium ionic liquids (IILs) with different fluorine-containing anions, i.e. imidazolium tetrafluoroborate (LB108), imidazolium hexafluorophosphate (LP108), imidazolium methyltributylammomiumbis ((trifluoromethyl)sulfonyl)imide ([HEMIM]NTf2), are selected as neat lubricant for electroplating Sn on Cu substrate under sliding electrical contact at room temperature (25 °C) and elevated temperatures (40 °C and 80 °C). All the IILs effectively reduce friction coefficient (0.28 for LB108 and LP108, 0.4 for [HEMIM]NTf2) and prevent Sn film from rapidly worn out and severe adhesive wear at 25 °C. However, at high temperatures, only LB108 well lubricate Sn-on-Sn contact up to 80 °C. It is found that, at 80 °C, the microstructure and chemical composition of the worn surface and the subsurface of the electroplating Sn are markedly modified due to two aspects: (1) temperature related phenomena (i.e. thermal diffusion of Cu to Sn film and even to SnO2 layer, as well as formation of intermetallic phase Cu6Sn5) and (2) interaction of the worn surface and IILs (i.e. adsorption, tribochemical interaction of the worn surface and the anion species, and diffusion of N species in Sn film). The interaction of the worn surface and the anion species of IILs plays an important role in wear reduction of electroplating Sn at 80 °C.

Synthesis, structures, electrochemical characterizations, theoretical and anticancer studies of Pd(II)-, Pt(II)- NHC complexes

We present the synthesis of two novel cationic Pd(II)- and Pt(II)- complexes ligated to a new C ∩ N donor N-heterocyclic carbene (NHC) ligand 3-methyl-1-(1-methyl-2-methylbenzoyl)imidazolin-2-ylidene, (1). Capitalizing 3-methyl-1-(1-methyl-2-methylbenzoyl)imidazolium hexafluorophosphate (1.HPF6), two novel isoelectronic and isostructural [Pd(1)2][PF6]2 (2), and [Pt(1)2][PF6]2 (3) complexes were synthesized. All the compounds were characterized by elemental analysis, 1H NMR, 13C NMR, IR, UV–Vis, mass spectroscopic studies, and finally single-crystal X-ray studies. X-ray crystallographic studies revealed both complexes 2 and 3 adopted square planar geometry. Electrochemical studies revealed Pt(II)/Pt(IV) reversible redox potential at 0.52 V. The catalytic activity of Pd(II)–NHC complex, 2 was tested for Suzuki coupling reactions. The structural assignments were further supported by DFT calculations. Molecular docking studies show a better binding affinity of 3 with Human-DNA Topoisomerase and BCL-2 protein compared to 2 and the scope of the complex 2 and 3 may be used as a drug. Cytotoxicity studies revealed that Pt(II)–NHC complex 3 is more potent than Pd(II)–NHC complex 2 against the breast cancer cell line (MCF-7) (IC50,7.9 ± 0.84 vs 6.0 ± 0.72 μM).

Novel-supported ionic liquid membranes for an effective removal of pentachlorophenol from wastewater

Recently ionic liquids (ILs) have been useful in many areas of wastewater treatment and separation processes in environmental engineering, such as supported ionic liquid membranes (SILM) based separations and solvent extraction applications. In this work novel ILs, namely 1-butyl-2,3-dimethyl imidazolium hexafluorophosphate [C4DMIM][PF6], tetrabutyl–phosphonium exafluorophosphate [TBP][PF6] were immobilized on PVDF (polyvinylidene fluoride) membrane for the removal of organic pollutant such as pentachlorophenol (PCP) from the water phase by SILM. Operating conditions like pH, feed and permeate concentration, membrane flux, and the mechanism was also studied. The interactions of H+ bonding, hydrophobic interactions, and carbon–π bonding interactions are explained via the SILM transport mechanism. The membranes were characterized by SEM, EDX, and FTIR analysis. In the experimental study, a high zetapotential of −93.24 mV was achieved, which is an indication of the excellent stability of SILM. At a pH of 4, [TBP][PF6] had the highest penetration rate of 87%. In contrast, [C4DMIM][PF6] yielded 79% after 30 h of experimentation at the feed pH 4. Similarly, after 30 h, [TBP][PF6] got the highest rate of permeation (80.50%), followed by [C4DMIM][PF6] (73.00%). The 0.1 M NaOH was used as a stripping agent in this study. PCP was successfully separated from the aqueous phase using two different hydrophobic ionic liquids as [C4DMIM][PF6] and [TBP][PF6]. This SILM technique has the potential in the future for further developments and for extracting organic contaminants from wastewater on a laboratory or industrial scale.

An ionic liquid‐enhanced soy protein adhesive with high bonding strength and antibacterial activity

AbstractTraditional formaldehyde resin adhesives can release harmful substances, which endanger human health and contribute to environmental pollution. The development of alternative high‐performance, environmentally benign adhesives is therefore of great importance. In this study, we evaluate the effect of several additives on the properties and performance of soy protein isolate adhesive, a bio‐based adhesive. Triglycidyl isocyanurate, a chemically cross‐linker, 1,3‐dimethyl imidazolium hexafluorophosphate ([MMIM]PF6), a crystalline ionic compound, and borax, which is covalently reactive with hydroxyl groups, were added to soy protein isolate to build a dense network structure. The wet shear strength of the adhesive prepared with all additives was 109% greater than that of the unmodified soy protein isolate adhesive (1.34 vs. 0.64 MPa). This improvement is due to the synergistic enhancement of the bonding strength through covalent cross‐linking and hydrogen‐bonding interactions. In addition, the anti‐fungal properties of the adhesive were significantly improved through the use of chemical additives. This work provides a new approach for the preparation of high‐performance, antimicrobial, bio‐based adhesives, which will be beneficial in the development of greener alternatives to commonplace chemicals.

Synthesis of High-Molecular-Weight Biobased Aliphatic Polyesters by Acyclic Diene Metathesis Polymerization in Ionic Liquids.

Acyclic diene metathesis (ADMET) polymerization of an α,ω-diene monomer of bis(undec-10-enoate) with isosorbide (M1) using a RuCl2(IMesH2)(CH-2-O i Pr-C6H4) (HG2, IMesH2 = 1,3-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene) catalyst and conducted at 50 °C (in vacuo) in ionic liquids (ILs) afforded higher-molecular-weight polymers (P1, M n = 32 200-39 200) than those reported previously (M n = 5600-14700). 1-n-Butyl-3-methyl imidazolium hexafluorophosphate ([Bmim]PF6) and 1-n-hexyl-3-methyl imidazolium bis(trifluoromethanesulfonyl)imide ([Hmim]TFSI) were suitable as effective solvents among a series of imidazolium salts and the pyridinium salts. The polymerization of α,ω-diene monomers of bis(undec-10-enoate) with isomannide (M2), 1,4-cyclohexanedimethanol (M3), and 1,4-butanediol (M4) in [Bmim]PF6 and [Hmim]TFSI also afforded the higher-molecular-weight polymers. The M n values in the resultant polymers did not decrease even under the scale-up conditions (300 mg to 1.0 g scale, M1, M2, and M4) in the polymerizations in [Hmim]TFSI; the subsequent reaction of P1 with ethylene (0.8 MPa, 50 °C, and 5 h) gave oligomers (proceeded via depolymerization). Tandem hydrogenation of the resultant unsaturated polymers (P1) in a [Bmim]PF6-toluene biphasic system upon the addition of Al2O3 (1.0 MPa H2 at 50 °C) gave the corresponding saturated polymers (HP1), which waswere isolated by a phase separation in the toluene layer. The [Bmim]PF6 layer containing the ruthenium catalyst could be recycled without a decrease in the activity/selectivity of the olefin hydrogenation at least eight times.

Ionic Liquid Functionalized Metal-Organic Framework ([DEIm][PF6]@MOF-5): Synthesis, Characterization, and Catalytic Application in the Reduction of 4-Nitrophenol.

A novel, unique, highly effective, and recyclable heterogeneous catalyst, diethyl imidazolium hexafluorophosphate ionic liquid supported metal-organic framework ([DEIm][PF6]@MOF-5), has been synthesized using a simple impregnation method at ambient temperature. Characterization of the catalyst was done through various techniques such as Fourier transform infrared (FTIR), energy dispersive X-ray, X-ray diffraction (XRD), transmission electron microscopy, scanning electron microscopy (SEM), elemental mapping, Raman spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis (TGA) analyses. The kinetic study has shown the high catalytic performance of [DEIm][PF6]@MOF-5 for the reduction of 4-nitrophenol (NP) compared to other catalysts. The catalyst also exhibited efficient electrochemical activity toward 4-NP reduction. The catalyst was recyclable for more than seven cycles without any significant loss in its catalytic performance. The recycled catalyst was further studied using XRD, FTIR, SEM, and TGA analyses to investigate the structural changes that occurred during the reaction. The catalyst maintained its structural integrity even after seven cycles.

Dinuclear silver(I)‐ and gold(I)‐ N heterocyclic carbene complexes; Synthesis, structural characterizations, photoluminescence and theoretical studies

Herein, a new family of cationic Ag(I)- and Au(I)-, complexes ligated to a novel C∩N donor N- heterocyclic carbene (NHC) ligand 3-methyl-1-(1-methyl-2-methylbenzoyl)imidazolin-2-ylidene, (1) are described. Compound 3-methyl-1-(1-methyl-2-methylbenzoyl)imidazolium hexafluorophosphate (1.HPF6) essentially serves as a carbene precursor that delivers the NHC carbene to Ag(I) and Au(I). The corresponding complex [{Ag(1)}{PF6}]2,(2), was prepared using mild base Ag2O and 3-methyl-1-(1-methyl-2-methylbenzoyl)imidazolium hexafluorophosphate (1.HPF6). Transmetallation method was capitalized to synthesize [{Au(1)}{PF6}]2,(3). All the novel compounds were characterized by elemental analysis, 1H NMR, 13C NMR, HR mass spectroscopic studies, and finally by single crystal X-ray studies. X-ray crystallographic studies revealed that the dinuclear complex 2 and 3 adopt linear geometry (Ccarbene-Ag/Au-Nimi) where strong Ag–Ag and Au–Au interaction present. The structural assignments were further supported by DFT calculations. TDDFT studies have been performed to inside into the electronic properties.

Removal of 2,4-dichlorophenol using ionic liquid [BMIM]+[PF6]- encapsulated PVDF membrane

2,4-Dichlorophenol (2,4-DCP) is one of the toxic chlorophenol compounds found in aquatic environments. Chlorophenols are priority pollutants, due to their high toxicity, mutagenicity and carcinogenicity. In this study, experiments were carried out for the removal of 2,4-Dichlorophenol (Cl2C6H3OH) from aqueous solution using commercial grade PVDF membrane immobilised with 1-Butyl-3-methyl imidazolium hexafluorophosphate [BMIM]+[PF6]- ionic liquid. Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FT-IR) used to identify and to confirm the surface morphology, functional groups and operational stability of Ionic Liquid [BMIM]+[PF6]- encapsulated PVDF membrane. The effect of various factors such as feed phase pH, initial 2,4-DCP concentration, operation time and stirring speed along with different stripping agents such as NaOH, KOH and NH4OH on the removal of chlorophenols has been investigated. The maximum permeation rate of 85.52% was achieved over an experimental run of 24 at pH 4 with a strip flux of 8.18323 × 10−09 mol m−2s−1 in 0.1 M NaOH strip phase.

RAFT polymerization-induced self-assembly of poly(ionic liquids) in ethanol

Abstract Poly(ionic liquids) (PILs) exhibit better durability, processability, and mechanical stability than ionic liquids. PIL self-assembly in green solvents is a well-established strategy for preparing polyelectrolytes. Reversible addition-fragmentation chain transfer (RAFT) polymerization-induced self-assembly (PISA) has proven to be the most controllable method for synthesizing polyelectrolytes. However, there have been few reports on preparing high-order morphology PILs by RAFT-PISA. A new type of ionic monomer, 1-butyl-3-(4-vinylbenzyl)imidazolium hexafluorophosphate ([BVBIm][PF6]), was prepared from substitution reaction and ion exchange reaction of 1-butylimidazole and 4-vinylbenzyl chloride. Herein, various morphologies, including spheres, worms, and vesicles, were easily obtained via RAFT ethanolic dispersion polymerization using poly(N,N-dimethylacrylamide) (PDMA43) as the macromolecular chain transfer agent and [BVBIm][PF6] as the monomer. Dispersion polymerization kinetic experiments, dynamic light scattering, transmission electron microscopy, and differential scanning calorimetry were used to investigate the PDMA43-b-P([BVBIm][PF6]) x block nanoparticles. This efficient RAFT-PISA method for preparing functionalized PIL nano-objects with controlled morphologies represents significant progress in this field.

Efficient surface treatment based on an ionic imidazolium hexafluorophosphate for improving the efficiency and stability of perovskite solar cells

Surface defects have been a primary limitation for perovskite solar cells (PSCs). Herein, the introduction of 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6) into the perovskite surface with the help of isopropanol (IPA) solvent can passivate the surface defects. The surface reconstruction of perovskite caused by IPA makes it easier for [BMIM]+ to passivate uncoordinated Pb2+ defects, [PF]6− to more easily replace and compensate unstable I−/Br− ions and I−/Br− vacancies. This forms large perovskite grains and island-like Cs0.05(MA0.12FA0.88)0.95Pb(I0.88Br0.12)3-x(PF6)x interlayers, which significantly reduces the defect-states density and inhibits recombination, and the energy barrier for the perovskite and the hole transport layer is also lowered. As a result, the open-circuit voltage was elevated from 1.112 to 1.181 V, and the efficiency for solar cells was also increased from 19.01% to 21.51%. In addition, the surface treatment of the hydrophobic BMIMPF6 can isolate the erosion of moisture and obtain better stability.

Selective CO2 Reduction to Ethylene Using Imidazolium-Functionalized Copper.

Electrochemical CO2 reduction is a promising approach to obtain sustainable chemicals in energy conversion. Improving the selectivity of CO2 reduction toward a particular C2 product such as ethylene remains a significant challenge. Herein, we report a series of imidazolium hexafluorophosphate compounds as surface modifiers for planar Cu foils to boost the Faradaic efficiency (FE) of ethylene from 5 to 73%, which is among the highest reported using polycrystalline Cu. The modified electrodes are convenient to prepare. The structure-function study demonstrates that varying the alkyl or aromatic substituents on the imidazolium nitrogen atoms has significant effects on the morphology of the deposited films and the product selectivity of CO2 reduction. Experimental FEC≥2, FEC2H4, ln(FEC≥2/FECH4), and ln(FEC2H4/FEC2H5OH) values show generally linear relationships with FEH2 while using different imidazolium modifiers, suggesting that factors governing proton reduction may also be directly related to both overall C≥2 generation and ethylene selectivity. This work presents an effective and practical way in tailoring the active sites of metallic surface for selective CO2 reduction.

Study of two green phosphonium‐based ionic liquids lubricants for steel/steel contact

AbstractThis study aims at the characterisation of physicochemical properties and tribological behaviour of quaternary phosphonium based ionic liquids (QPILs) P44414Sac and P44414Ace at ambient temperature and elevated temperature. The kinematic viscosity, viscosity index (VI), thermal stability, corrosivity and tribological properties of the ionic liquids (ILs) were systematically investigated. The copper strip corrosion test results revealed that the two green ILs are non‐corrosive because of their halogen‐free characteristic. Tribological data demonstrated that the present ILs exhibited extremely superior friction‐reducing and anti‐wear properties to conventional IL lubricant 1‐Butyl‐3‐methylimidazolium hexafluorophosphate (L‐P104), 1‐n‐Octyl‐3‐methyl imidazolium hexafluorophosphate (L‐P108) and commercially available synthetic oil PAO10. Electrical contact resistance (ECR) and surface analysis of the worn‐out steel disc surfaces revealed that the synergistic effect of a polarity induced physical adsorption layer and a tribo‐chemical reaction film formed a boundary film to protect steel‐steel contact between rubbing surfaces.

Synthesis of Diazoquinones and Azidophenols via Diazo‐Transfer Reaction of Phenols

AbstractThe first efficient diazo‐transfer reaction of phenols is described. o‐Quinone diazides (diazoquinones) were prepared from phenols in high yields by the diazo‐transfer reaction using 2‐azido‐1,3‐bis(2,6‐diisopropylphenyl)imidazolium hexafluorophosphate (IPrAP, 2‐PF6), which is a safe and stable crystalline. The reaction efficiently proceeded in methanol in the presence of a base. Phenols substituted with electron‐donating groups reacted more smoothly than those having electron withdrawing groups. Reactive phenols were diazotized by IPrAP with iPr2NH as a base, and low reactive phenols were diazotized with N,N‐dimethyl‐4‐aminopyridine (DMAP). Furthermore, the formed diazoquinones reacted with sodium azide in 2‐methoxyethanol and afforded the corresponding azidophenol in high yields.

In Situ XANES Studies on Extracted Copper from Scrap Cu/ITO Thin Film in an Ionic Liquid Containing Iodine/Iodide.

Copper is coated on indium-tin-oxide (ITO) thin film to improve its electrical resistivity. In order to recycle the scrap Cu/ITO thin film, an ionic liquid (1-butyl-3-methyl imidazolium hexafluorophosphate ([C4mim][PF6])) containing iodine/iodide (IL-I) was used to extract copper at 303, 343, 413, 374, and 543 K. The extraction efficiency of copper from the scrap Cu/ITO thin film was >99% with IL-I. Using XRD, crystal In2O3 was found on the regenerated ITO thin film which had a resistivity similar to that of unused ITO thin film. Using X-ray absorption near edge structural (XANES) spectroscopy, at least two paths for the extraction of copper from the Cu/ITO thin film into IL-I were identified. Path I: Copper is stripped from the scrap Cu/ITO thin film and then interacts with I3− in the IL-I to form nano CuI. The nano CuI further interacts with I−. Path II: Copper interacts with I3− on the surface of the Cu/ITO thin film to form nano CuI. The nano CuI is further stripped into the IL-I to interact with I−. During extraction, the nanoparticle size could be increased in the IL-I by conglomeration due to fewer coordinating anions and decrease in the viscosity of IL-I at high temperatures. Furthermore, nanoparticle growth was affected by [PF6]− of the IL-I determined via 31P NMR.