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Deep eutectic solvents (DESs), as ionic liquid analogues for green solvents, have gained increasing attentions in chemistry. In this work, three typical kinds of DESs (ChCl/Gly, ChCl/AcOH and ChCl/Urea) were successfully synthesized and characterized by Fourier transform infrared spectroscopy (FTIR) and Raman. Then comprehensive and systematical analyses were performed by the methods of density functional theory (DFT). Two methods (B3LYP/6-311++G(2d,p) and dispersion-corrected B3LYP-D3/6-311++G(2d,p)) were employed to investigate the structures, vibrational frequencies and assign their ownership of vibrational modes for the DESs, respectively. Nearly all the experimental characteristic peaks of IR and Raman were identified according to the calculated results. By linear fitting of the combined calculated vs experimental vibration frequencies, it can be found that both of the two methods are excellent to reproduce the experimental results. Besides, hydrogen bonds were proved to exist in DESs by IR spectrum, structure analysis and RDG analysis. This work was aimed at predicting and understanding the vibrational spectra of the three typical DESs based on DFT methods. Moreover, by comparing experimental and theoretical results, it provides us a deep understanding of the formation mechanisms of DESs., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Acidic deep eutectic solvents (DESs) have been considered desirable extractants and catalysts for desulfurization. However, their hydrogen bond donors (HBDs) are usually sole organic acids, which are not conducive to efficient green catalysis. Herein, a novel inorganic–organic dual-acid DES (DADES) was reported for efficient extractive and oxidative desulfurization. Benefiting from the physical interaction among the three components in a DADES, a transparent homogeneous liquid can be obtained even though inorganic acid (boric acid, BA) and organic acid (acetic acid, AA) can be immiscible. Furthermore, the dual-acid HBD can increase the acidity of the DADES and reduce its viscosity, accelerating its mass transfer efficiency and enhancing its catalytic activity. With 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) as the hydrogen bond acceptor, [Bmim]Cl/BA/0.3AA effectively activated hydrogen peroxide and achieved sulfur removal of 96.6% at 40 °C. Furthermore, the universality of the synergistic effect in various DADESs was confirmed by the modulation of the types of organic acids. This study not only motivates the construction of more intriguing novel DESs based on the DADES concept but also highlights their potential in clean fuel production. [ABSTRACT FROM AUTHOR]

Highlights • Sn based DESs with urea were firstly synthesized and introduced into hexagonal boron nitride. • Sn based DESs with urea were served as both reaction solvents and metal sources. • These materials present higher adsorption capacity for dibenzothiophene (DBT) from model oils. • The nature of the ADS source from the π-complexation and hydrogen bonding interaction between SnO 2 and DBT. Graphical abstract Sn based DESs with urea were firstly synthesized and introduced into hexagonal boron nitride. These materials present higher adsorption capacity for dibenzothiophene (DBT) from model oils. The nature of the ADS source from the π-complexation and hydrogen bonding interaction between SnO 2 and DBT. Abstract Adsorptive desulfurization (ADS) from fuels is considered as the most promising strategy due to the advantage of low energy consumption, to treat on sulfur which would induce serious air pollution. In this work, Sn-based DESs with urea were firstly synthesized and introduced into hexagonal boron nitride (h-BN) as both reaction solvents and metal sources. Adsorption experiments show that the as-prepared adsorbents present higher adsorption capacity for dibenzothiophene (DBT) from model oils as compared with the commercial BN. Especially, the Sn-BN-800 (SnO 2 supported BN with OH groups substitution at B sites) shows the highest performance. By combining experimental and theoretical analysis, we propose that the performance enhancement arises from the π-complexation and hydrogen bonding interaction between SnO 2 and DBT. In addition, the OH groups, which were substituted at the edge site of B, may also enhance the electron transfer from DBT to Sn-BN-800, leading to the improved adsorption capacity. [ABSTRACT FROM AUTHOR]

Five low-cost deep eutectic solvents (DESs) were synthesized based on choline chloride (ChCl) and a series of straight-chain monobasic acids. Under UV light irradiation, one-pot extraction combined with the metal-free photochemical aerobic oxidative deep desulfurization of fuels in deep eutectic solvents was successfully achieved. This liquid-liquid extraction and photochemical oxidative desulfurization system (EPODS) comprised of air, isobutylaldehyde (IBA), DESs and model oil. The factors influencing sulfur removal were systematically investigated, including the amount of DES, volume ratio of model oil and IBA, different sulfur concentrations, different substrates and fuel composition. The sulfur removal of dibenzothiphene (DBT) could reach 98.6% with air as oxidizing agent under UV light irradiation. Sulfur removal by different sulfur compounds decreased as BT ＞ DBT ＞ 4,6-DMDBT. The possible photochemical oxidative desulfurization mechanism was researched by gas chromatograph-mass spectrometer (GC-MS), electron spin-resonance (ESR) spectroscopy and density functional theory (DFT). [ABSTRACT FROM AUTHOR]

A bifunctional guanidine-functionalized basic binuclear poly(ionic liquid)s were successfully prepared ternary copolymerization of binuclear bromine ILs, guanidine functionalized binuclear ILs and DVB by free radical polymerization, which were applied for one-pot efficiently catalyzing the cycloaddition of the simulated flue gas (15% CO 2 + 85% N 2) without any co-catalyst. [Display omitted] • Novel guanidine-functionalized basic binuclear poly(ionic liquid)s (GB-PILs) are successfully prepared. • GB-PILs provide the built abundant pores and the exposed bromine anions. • GB-PILs can efficiently catalyze the CO 2 cycloaddition of the simulated flue gas without solvent and cocatalyst. • The mechanism of co-catalyzing the cycloaddition reaction of CO 2 and epoxide with guanidine basic sites and binuclear ones in P-DBTMGH catalyst is explored. The direct conversion of low partial pressure (10–15 %) from industrial waste gas into high value-added chemicals provides a favorable solution to global climate change. However, developing high-efficient catalysts for the conversion of low partial pressure CO 2 under mild conditions is still a major challenge. Here, guanidine-functionalized basic binuclear poly(ionic liquid)s (P-DBTMGH) were prepared by free radical copolymerization. With the introduction of guanidine ionic liquids into the framework of GB-PILs, the alkalinity in the structure was improved, and thus enhancing CO 2 surface adsorption and activation ability. Meanwhile, bromide containing binuclear sites help to increase the ion density of bromide and promote the occurrence of ring opening. Using epichlorohydrin as a probe substrate, P-DBTMGH could efficiently catalyze the cycloaddition reaction of the simulated flue gas (15 vol% CO 2 + 85 vol% N 2) without any co-catalyst or solvent, and chloropropene carbonate (CPC) with a selectivity and yield of 99 % and 96 % was obtained, which was better than or equivalent to the results reported previously. Moreover, the theoretical studies deeply understood the synergetic effect of guanidine basic sites and bromide containing binuclear sites on CO 2 activation and ring-opening of epoxides, which provides a better choice for high-value utilization of low partial pressure CO 2 from flue gas. [ABSTRACT FROM AUTHOR]

• A novel electronic modulation strategy on metal-free catalyst via organic modification was proposed. • The electron transfer effect was well proved and the electron transfer direction was clarified. • A deep oxidative desulfurization can be achieved with the residual sulfur content less than 10 ppm. • The mechanism of the improved catalytic activity was illustrated clearly. Tuning electronic structure of metal catalysts by organic modification is an efficient strategy for domination of their catalytic performances. However, the electronic structure tuning over metal-free catalysts remains to be a challenge. In this work, an organic modification strategy with deep eutectic solvents (DES) as organic modifier over metal-free catalysts was proposed to tune the electronic structure of hexagonal boron nitride (h-BN). Detailed experiments showed that the electronic properties of h-BN was rationally tuned by the introduced DES, in which the B atoms in h-BN were positively charged. Meanwhile, the modulated electronic properties can lower the activation energy for the generation of hydroxyl radicals (•OH) from hydrogen peroxide (H 2 O 2), thus leading to a promoted catalytic performance in oxidative desulfurization. This finding may pave a new strategy for tuning metal-free catalysts with highly-active catalytic performance. An organic ligand modification strategy over metal-free boron nitride catalyst. [Display omitted] [ABSTRACT FROM AUTHOR]

• Dual Brønsted DESs were designed as extractants and catalysts for oxidative desulfurization. • The reaction mechanism was studied in depth through experimental and theoretical method. • Synergistic effect made the DES showed higher catalytic activity than other DESs. • Decreasing viscosity of DES was verified as effective strategy to improve reaction rate. Deep eutectic solvents (DESs) are generally used as attractive solvents or extractants rather than catalysts in the field of synthesis and separation. Herein, dual Brønsted acidic DESs were prepared by mixing sulfonated quaternary ammonium and oxalic acid as extractants and catalysts for deep oxidative desulfurization. Compared to the DESs with single acidic group, the dual acidic DESs exhibited much higher catalytic activity likely due to the synergistic effect. The 1H NMR study indicated that the weak interaction between DES and sulfur compounds led to a low extraction capacity. However, the sulfur removal could reach 97.7% under optimized reaction conditions. Density functional theory (DFT) calculations demonstrated that sulfonic group and carboxylic group are of equal importance to desulfurization performance. Further, the desulfurization efficiency was also strongly affected by the viscosity of DESs. Here, we put forward a new strategy that the reaction time could be sharply shortened to 40 min and 100 min by adding low viscous acetonitrile and polyethylene glycol into DES to form mixing reaction system, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • The minimum water content for a stable MA:S:W NADES was in a molar ratio of 1:1:3. • The effect of water on the properties of NADESs was explored. • The nanostructure of NADESs was studied experimentally and theoretically. • Water bridges the other two components through hydrogen bonds. • Solvation effect of water facilitates the proton transfer. Natural deep eutectic solvents (NADESs) have drawn significant attention as green solvents for their special properties like biodegradability and biocompatibility. Nevertheless, the high viscosity of NADESs tends to prevent their implementation in industry. Even though dilution with water will lower the viscosity of NADESs effectively, fundamental knowledge of the intermolecular network in NADESs as well as the effect of water on the cooperative hydrogen-bonding network has not been evaluated systematically. Herein, solutions spanning a range of molar ratios of DL-Malic acid, L-Serine and water were synthesized. The experimental results demonstrate that it takes at least three moles of water to achieve a stable NADES. Besides, density functional theory (DFT) calculations indicate that water molecules connect DL-Malic acid and L-Serine by a water bridge framework. Furthermore, the progressive addition of water facilitates the proton transfer, making the hydrogen atom of the carboxyl group gradually ionize and approach the amino group. We hope the findings would provide a better understanding of the structural characteristics of NADESs and shed light on the applications. [ABSTRACT FROM AUTHOR]

Convenient synthesis of deep eutectic solvent for effective, selective, and reversible capture of SO 2. [Display omitted] • Pyridine based DESs could be received through a facile procedure with a low cost. • The obtained DESs show remarkable absorption capacity & rapid absorption rates. • DESs' desirable selectivity & cycling performance indicates its potential usage. • The absorption process was revealed in detail via FT-IR, NMR & DFT calculations. In this study, deep eutectic solvents (DESs) consisting of 1-ethyl-3-methylimidazolium chloride (EmimCl) and pyridine derivatives were prepared through a facile procedure. The studied DESs exhibit superb absorption behavior for SO 2 at 298.15 K and 1.0 bar, of which per g EmimCl: 2-NH 2 Py (7: 1) could capture 1.247 g SO 2 , exceeding the vast majority of the previously reported DESs and ionic liquids (ILs). The factors that could affect the absorption capacity were explored orderly, like the category and molar ratio of pyridine derivatives, the absorption temperature, and SO 2 partial pressure. Based on the above investigation, EmimCl: 2-NH 2 Py (7: 1) exhibits rapid equilibration time (<45 s), outstanding SO 2 /CO 2 selectivity (312/1), and ultra-high recycling performance (40 times), which is far superior to the other reported DESs and ILs. In addition, the possible absorption process was studied from both experimental and theoretical aspects. The obtained data indicate that Lewis acid-base interaction and SO 2 ···Cl- covalent interaction both exist between SO 2 and DES, leading to an ideal absorption capacity and selectivity for SO 2. This study might provide a novel insight to remove SO 2 and other gaseous pollutants. [ABSTRACT FROM AUTHOR]

Deep eutectic solvents (DESs) have been deemed as green solvents due to their similar physical properties to ionic liquids. The most advantage of DESs, especially choline chloride-based DESs, is that they are biodegradable and non-toxic. In this work, several choline-like DESs are synthetized and characterized by 1 H NMR, FTIR, UV-vis, Raman and ESI–MS. The DESs with different straight alkyl chains linked to N atom were studied. It is found that [C 12 DMEA]Cl/FeCl 3 shows the best performance and 52.9% of desulfurization efficiency is obtained. For comparison, two kinds of phenyl substituted DESs, [BzMDEA]Cl/FeCl 3 and [BzMDEA]Cl/FeCl 3 , are employed to investigate the extractive mechanism. The result shows that CH-π interaction may be much stronger than π-π interaction in this reseasch. The DESs can be regenerated by water and the extractive efficiency is almost not declined. [ABSTRACT FROM AUTHOR]

• Isothermal saturation method was used to measure the solubility of 1-(4-tert-butyl-2,6-dimethylphenyl)ethenone in eight pure solvents and two binary solvents at temperatures ranging from 273.15 K to 308.15 K. • Analysis of 1-(4-tert-butyl-2,6-dimethylphenyl)ethenone by DSC and XRD. • Van't Hoff model, modified Apelblat model, NRTL model, Wilson model, Jouyban − Acree model, Sun model were used to correlate the solubility of 1-(4-tert-butyl-2,6-dimethylphenyl)ethenone. • Hansen solubility parameter was used to reveal the solubility behavior of 1-(4-tert-butyl-2,6-dimethylphenyl)ethenone. • The thermodynamic properties (Δ sol H°, Δ sol S°, Δ sol G°, %ξ H and %ξ TS) were discussed by van't Hoff equation. In this work, the solubility of 1-(4-tert-butyl-2,6-dimethylphenyl)ethenone was measured and correlated by isothermal saturation method in eight pure solvents (isopropyl alcohol, n -octanol, ethyl acetate, acetonitrile, ethanol, acetone, cyclohexane, methanol) and two binary solvents (isopropyl alcohol + ethyl acetate, ethanol + acetonitrile) at temperatures ranging from 273.15 K to 308.15 K. The results show that the solubility of 1-(4-tert-butyl-2,6-dimethylphenyl)ethenone in the selected solvent is positively correlated with temperature. The experimental solubility data were correlated by six thermodynamic models, including Van't Hoff equation, modified Apelblat equation, NRTL model, Wilson model, Jouyban − Acree model and Sun model. The values of RAD and RMSD showed that these models fit the solubility data well. Besides, Hansen solubility parameter was used to reveal the solubility behavior of 1-(4-tert-butyl-2,6-dimethylphenyl)ethenone. Finally, the thermodynamic propertie Δ sol H○, Δ sol S○, Δ sol G○, %ξ H and %ξ TS were calculated by van't Hoff equation. The results showed Δ sol H○, Δ sol G○, Δ sol S○, are all positive values, indicating that the dissolution process in selected solvents was entropy-driven and endothermic. [ABSTRACT FROM AUTHOR]

A supported SiW 12 O 40 -based ionic liquid (SiW-IL) catalyst with high catalytic activity is designed and synthesized by sol–gel method. The supported catalyst had amphiphilic property, making it exhibit good catalytic performance in solvent-free oxidative desulfurization system. The removal of dibenzothiophene (DBT) with the supported catalyst reached 99.9%, while the sulfur removal is only 6.3% with SiW-IL. The characterizations show that SiW-IL is supported on the carrier successfully and the supported catalyst had a sheet-shaped morphology. Then, various of experimental conditions were taken into consideration to investigate the influences of the desulfurization efficiency and the optimal conditions were obtained. Additionally, sulfur removal of different substrates decreased in the following orders: DBT > 4-MDBT > 4,6-DMDBT > BT under the same conditions. GC–MS analysis was employed to study the mechanism of the desulfurization, DBT sulfone was proved to be the oxidizing product of DBT. Moreover, the supported catalyst had a good thermal and chemical stability, and sulfur removal of DBT still remained 96.2% after recycling 7 times. [ABSTRACT FROM AUTHOR]

Bismuth phosphate (BiPO 4 ) has been researched as one of the important bismuth-containing salts with high-efficient photocatalytic activity under UV light irradiation. However, the morphologies and microstructures of BiPO 4 photocatalyst on photocatalytic activity have not been clearly investigated. Herein, BiPO 4 photocatalyst with various morphologies and microstructures have been synthesized via a facile reactable ionic liquid [Omim]H 2 PO 4 assisted solvothermal process in H 2 O, ethanol, ethylene glycol (EG) and ethylene glycol monomethyl ether (EGME), respectively. The photocatalytic ability of the as-prepared samples was evaluated using ciprofloxacin (CIP) as target pollutant. The result implied that different photocatalytic activities for CIP degradation is mainly attributed to different morphologies and microstructures of BiPO 4 samples prepared in different solvents. The BiPO 4 sample which was prepared under H 2 O condition showed the highest photocatalytic activity. In addition, inorganic salt NaH 2 PO 4 ·2H 2 O was utilized to prepare BiPO 4 samples instead of [Omim]H 2 PO 4 . It can be found that the photocatalytic efficiency of BiPO 4 prepared via ionic liquid exhibited higher photocatalytic activity than that of inorganic salt for the degradation of CIP under UV light irradiation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Seven AA-ChCl DESs have been systematically synthesized and investigated. • The indistinguishable vibrational modes of C H or O H are identified in IR. • The chemical shifts of inactive hydrogen atoms are assigned that cannot be directly confirmed. • The liquid form of the AA-ChCl DESs mainly depends on the O H···Cl and O H···O interaction. • The O H···Cl interaction strength decreased with the alkyl chain of aliphatic acids increasing. Deep eutectic solvents (DESs) are considered as "green solvents". In this work, seven aliphatic acid-choline chloride DESs (AA-ChCl DESs) were successfully prepared. With the help of density functional theory (DFT) calculations, the experimental peaks that cannot be directly or accurately confirmed have been identified. The formation mechanism was studied with Fourier transform infrared (FT-IR) and 1H nuclear magnetic resonance (1H NMR) spectroscopy and DFT calculation. The liquid formation of the AA-ChCl DESs mainly depends on two forces, the hydrogen bonds of O H···Cl and O H···O. Among them, the O H···Cl play a leading role. The O H···Cl interaction strength decreased with the alkyl chain of aliphatic acids due to the increase of intermolecular distance, which means that the formation ability of AA-ChCl decreased gradually. It hopes that the current work can provide useful information to design DESs and expand their potential applications. [ABSTRACT FROM AUTHOR]

• The type IV DESs were synthesized successfully through coordination. • The type IV DESs are usded for EDSs of diesel fuel for the first time. • DESs formed by ZnCl 2 and N-methylformanilide showed high extractive performance. • The Nernst partition coefficient (K N) reached as high as 2.41. • The extraction mechanism was investigated by experimental and theoretical analysis. As promising green alternative solvents for ionic liquids, deep eutectic solvents (DESs) have been widely used in separation, catalysis, synthesis, etc. Most of the researches have focused on the application of DESs formed by hydrogen bonding interaction. In this paper, amide-based type IV DESs were synthesized from metal chloride and amides with coordination interaction, and they were used for extractive desulfurization of fuels. The experimental results showed the DES ZnCl 2 /N-methylformanilide (ZnCl 2 /MFA) had the highest desulfurization efficiency with the Nernst partition coefficient (K N) as 2.41. The extraction mechanism was firstly explored by Fourier transform infrared spectrometer (FT-IR) and 1H nuclear magnetic resonance (1H NMR). Then density functional theory (DFT) study suggested that π-π interactions and C H···π interactions contribute mainly to effective removal of DBT from fuel oil by DESs. [ABSTRACT FROM AUTHOR]

Developing an adsorbent with optimal absorption capacity for SO 2 elimination has been an important issue, yet a great challenge remains. Herein, we initiated a series of ternary deep eutectic solvents (DESs), consisting of diethylenetriamine (DETA), ethylene glycol (EG) and 1-ethyl-3-methylimidazolium chloride ([Emim]Cl) with various molar ratio for the systematical investigation of SO 2 absorption. It was found that DES with the molar ratio of 2: 1: 2 (DETA: EG: [Emim]Cl) exhibits remarkable absorption capacity (1.02 g SO 2 /g DES) and robust reusability for SO 2 at room temperature and ambient pressure, which is distinctively higher than most of the reported binary DESs so far. Moreover, FT-IR, 1H NMR, 13C NMR together with DFT calculations were adopted to clarify the absorption mechanism for SO 2. It indicates that the remarkable absorption capacity might be ascribed to the existence of multiple absorption sites. Therefore, this study offers a promising alternative for the design and preparation of highly effective absorbents for gas elimination. Highly efficient and reversible capture of SO 2 by facile synthesized ternary deep eutectic solvents with multiple absorption sites. [Display omitted] • Green DESs can be obtained through a facile procedure with relatively lower cost. • Enhanced absorption capacity and desired cycling performance can be received. • Multiple absorption sites in DES were proved by experiments and DFT calculations. [ABSTRACT FROM AUTHOR]

In this work, solubility of musk ketone in four binary solvents (methanol + ethyl acetate, isopropanol + ethyl acetate, n-hexane + ethyl acetate, n-heptane + ethyl acetate) was experimentally studied by employing the isothermal saturation method at (273.15 to 313.15) K under 101.3kPa. The results show that the solubility of musk ketone increases with the increase of temperature and the mole fraction of ethyl acetate. Hansen solubility parameter was used to reveal the solubility behavior of musk ketone. The experimental solubility data in binary solvents were correlated by the λh equation, modified Apelblat equation, Van't Hoff equation, Jouyban−Acree model, Sun model. The values of RD and RMSD indicated that these models fit the solubility data well in binary solvents. The thermodynamic properties (Δ sol H°, Δ sol S° , Δ sol G° , %ξ H and %ξ TS) were discussed by van't Hoff equation. The results show that the force for the dissolution process was entropy-driven and the dissolution process was endothermic. • The solubility of musk ketone in four binary mixed solvents was measured. • Analysis of musk ketone by DSC and XRD. • Five models were used to correlate the solubility date. • Hansen solubility parameter was used to reveal the miscibility of musk ketone. • The thermodynamic properties were discussed by van't Hoff equation. [ABSTRACT FROM AUTHOR]