4333-62-4Relevant academic research and scientific papers
Experimental and theoretical studies on imidazolium ionic liquid-promoted conversion of fructose to 5-hydroxymethylfurfural
Li, Yu-Nong,He, Liang-Nian,Yang, Zhen-Zhen,Liu, An-Hua,Yu, Bing,Luan, Chao-Ran,Wang, Jin-Quan
, p. 2752 - 2758,7 (2012)
A combined experimental and computational study on the imidazolium ionic liquid-promoted conversion of fructose to 5-hydroxymethylfurfural (HMF) was performed. In particular, 1-butyl-3-methyl-imidazolium bromide (BMImBr) was found to be unexpectedly effective for conversion of fructose into HMF without utilizing any other additive or catalyst. Under the optimized conditions, nearly 100% conversion of fructose with a 95% yield of HMF could be obtained. In addition, BMImBr could be easily recovered and reused over 6 times without significant loss of activity. This protocol represents a simple, recyclable and environmentally friendly pathway for HMF production. Furthermore, the detailed mechanism of the BMImBr-promoted conversion of fructose into HMF was also studied through an in situ FT-IR technique, NMR and density functional theory calculations, and demonstrated that the hydrogen bond interaction between BMImBr and fructose could play an important role in promoting the dehydration of fructose. This work also provides further understanding at the molecular level of the reaction process for ionic liquid-promoted conversion of fructose to HMF.
Photochemical Reduction of CO2 Using 1,3-Dimethylimidazolylidene
Denning, Derek M.,Thum, Matthew D.,Falvey, Daniel E.
, p. 4152 - 4155 (2015)
Product analysis along with fluorescence quenching and laser flash photolysis experiments demonstrate that it is possible to effect a net photochemical reduction of CO2 through photolysis of an excited state donor in the presence of 1,3-dimethylimidazolium-2-carboxylate.
Imidazolium bromide-based ionic liquid assisted improved activity of trypsin in cationic reverse micelles
Debnath, Sisir,Das, Dibyendu,Dutta, Sounak,Das, Prasanta Kumar
, p. 4080 - 4086 (2010)
The present work reports the imidazolium-based ionic liquids (ILs) assisted enhancement in activity of water-pool solubilized enzyme trypsin in cationic reverse micelles of CTAB. A set of imidazolium ILs (1-alkyl-3-methyl imidazolium bromides) were prepared with varying lengths of their side armwhich results in the differential location of these organic salts in the reverse micelles. The different ILs offered varied activating effects on the biocatalyst. The activity of trypsin improved 30-300% in the presence of 0.1-10 mM of different ILs in reverse micelles of CTAB. Trypsin showed 300% (4-fold) increment in its activity in the presence of IL2 (1-ethyl-3-methyl imidazoliumbromide,EMIMBr) compared to that observed in the absence of IL in CTAB reverse micelles. The imidazolium moiety of the IL, resembling the histidine amino acid component of the catalytic triad of hydrolases and itsBr- counterion, presumably increases the nucleophilicity of water in the vicinity of the enzyme by forming a hydrogen bond that facilitates the enzyme-catalyzed hydrolysis of the ester.However, the ILs with increasing amphiphilic character had little to no effect on the activity of trypsin due to their increased distance from the biocatalyst, as they tend to get localized toward the interfacial region of the aggregates. Dynamic light scattering experimentationwas carried out in the presence of ILs to find a possible correlation between the trypsin activity and the size of the aggregates. In concurrencewith the observed highest activity in the presence of IL2, the circular dichroism (CD) spectrum of trypsin in CTAB reverse micelles doped with IL 2 exhibited the lowest mean residue ellipticity (MRE), which is closest to that of the native protein in aqueous buffer.
Photochemistry of imidazolium cations. Water addition to methylimidazolium ring induced by UV radiation in aqueous solution
Sarmiento, Gabriela P.,Zelcer, Andrés,Espinosa, Mariela S.,Babay, Paola A.,Mirenda, Martin
, p. 155 - 163 (2016)
The UV-C induced photoaddition of water to N-alkyl-N′-methylimidazolium cations was studied. The main photoreaction products exhibit chemical additions of a proton and a hydroxyl group to either positions 4 or 5 of the imidazolium ring. For unsymmetrical imidazolium cations, two positional isomers were obtained as products. In these cases, the most abundant isomer is the one in which the hydroxyl group adds at the side of the ring having the longer alkyl substituent. Experiments performed in D2O solutions reveal that the additions of proton and hydroxyl group never take place at the same carbon atom, in a reaction that produces equal amounts of diastereoisomers. Moreover, the formation of diastereoisomers at equal proportions suggests that the reaction proceeds in an unconcerted fashion.
Expanding the catalytic activity of nucleophilic N-heterocyclic carbenes for transesterification reactions
Nyce, Gregory W.,Lamboy, Jorge A.,Connor, Eric F.,Waymouth, Robert M.,Hedrick, James L.
, p. 3587 - 3590 (2002)
(graph presented) Currently, there is a renewed interest in reactions that are catalyzed by organic compounds. Typical organic catalysts for acylation or transesterification reactions are based on either nucleophilic tertiary amines or phosphines. This communication discusses the use of nucleophilic N-heterocyclic carbenes as efficient transesterification catalysts. These relatively unexplored and highly versatile organic catalysts were found to be mild, selective, and more active than traditional organic nucleophiles.
New room-temperature ionic liquids with C2-symmetrical imidazolium cations
Dzyuba,Bartsch
, p. 1466 - 1467 (2001)
New 1,3-dialkylimidazolium hexafluorophosphates with two butyl, pentyl, octyl, nonyl or decyl groups are room temperature ionic liquids.
Synthesis of biphenyl-4,4′-diylbis(naphthalene-1-ylmethanone) via carbonylative coupling
Song, Ju Hyun
, p. 3031 - 3034 (2015)
More recently, an interest has been developed in three component carbonylation reactions, such as the carbonylative Suzuki, carbonylative Sonogashira and carbonylative Heck reactions, which allow for a significant increase in molecular complexity. To develop a luminescent material with high colour purity, luminous efficiency and stability, we synthesized diketone by carbonylative Suzuki coupling in the presence of Pd(NHC)(NHC=N-heterocyclic carbene) complex as the catalyst. Carbonylative coupling of 4,4′-diiodobiphenyl and naphthalene-1-ylboronic acid was investigated to study the catalytic ability of Pd(NHC) complex. Reactions were carried out using both CO and metal carbonyls. bis(1,3-Dihydro-1,3-dimethyl-2H-imidazol-2-ylidene)diiodopalladium was used as the catalytic complex. Reaction products biphenyl-4,4′-diylbis(naphthalene-1-ylmethanone) 3 and (4′-iodobiphenyl-4yl)(naphthalene-1-yl)methanone 4 were obtained as a result of CO insertion into the palladium(II)-aryl bond. However, when pyridine-4-ylboronic acid was used in place of naphthalene-1-ylboronic acid as the starting reagent, synthetic reaction yielding 3 and 4 were found.
Electrochemical and physicochemical properties of redox ionic liquids using electroactive anions: Influence of alkylimidazolium chain length
Xie, Han Jin,Gélinas, Bruno,Rochefort, Dominic
, p. 283 - 289 (2016)
Ferrocenylsulfonyl(trifluoromethylsulfonyl)imide [FcNTf] is reported as a redox anionic species used to obtain an electroactive ionic liquid with a typical alkylimidazolium cation. Here, several of these redox ionic liquids (RILs) were prepared by combining FcNTf with alkylimidazolium cations in order to understand the influence of symmetry and alkyl chain length on the RIL system. The physicochemical and electrochemical properties are characterized for [CxCyIm][FcNTf], where x and y were varied between 1 and 8, both in the pure, undiluted state and in solutions of acetonitrile. In pure form, the ionic conductivity of [CxCyIm][FcNTf] was found to range between 0.22 and 0.42 mS cm-1 at 60 °C, and the alkyl chain length was found to have a similar effect on viscosity as in conventional imidazolium-NTf2 ionic liquids. While an increase in alkyl chain length increases viscosity and decreases mass transport, it was found to have no effect on the redox potential of the ferrocene center. The cyclic voltammetry of [CxCyIm][FcNTf] solutions diluted in acetonitrile exhibited behavior which depends on concentration and on the presence of a supporting electrolyte. At concentrations above 50 wt.% and in the absence of any supporting electrolyte, the electroactive anion was found to deposit as a dense film on the electrode upon oxidation. This behavior is linked to formation of Fc+NTf- zwitterions, which accumulates in the double-layer and precipitates on the electrode surface. This study also investigates the electrochemical properties of film deposition.
A new method for improving the ion conductivity of anion exchange membranes by using TiO2 nanoparticles coated with ionic liquid
Chu, Yuhao,Chen, Yuenan,Chen, Nanjun,Wang, Fanghui,Zhu, Hong
, p. 96768 - 96777 (2016)
Recently a new method for increasing the ion conductivity of anion exchange membranes (AEM) was developed based on the novel materials ionic liquids (ILs). We mixed the ILs into the membrane directly instead of immobilizing onto the polymer backbone as in the traditional way. Nano-TiO2 was introduced to stabilize the ILs in the membrane. The ILs were immobilized by the nano-TiO2, acting as the "active sites" in the membrane, to enhance the mobility of the hydroxyl groups so as to increase the ion conductivity. Both pure ILs composite membranes and ILs-TiO2 composite membranes were synthesized, and their properties were compared. 1H nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy were used to analyze the structures of the composite membranes. The mechanical properties, thermal stabilities, ion conductivities, water uptakes, swelling ratios, and ion exchange capacities of the membranes were investigated. The interaction between the TiO2 and ionic liquids was confirmed by X-ray diffraction. The stability of the ILs in the membrane was measured comprehensively. All these results show that this novel method is effective and promising for AEM applications.
Iridium(I) Compounds as Prospective Anticancer Agents: Solution Chemistry, Antiproliferative Profiles and Protein Interactions for a Series of Iridium(I) N-Heterocyclic Carbene Complexes
Gothe, Yvonne,Marzo, Tiziano,Messori, Luigi,Metzler-Nolte, Nils
, p. 12487 - 12494 (2016)
A series of structurally related mono- and bis-NHC–iridium(I) (NHC: N-heterocyclic carbene) complexes have been investigated for their suitability as potential anticancer drugs. Their spectral behaviour in aqueous buffers under physiological-like conditions and their cytotoxicity against the cancer cell lines MCF-7 and HT-29 are reported. Notably, almost all complexes exhibit significant cytotoxic effects towards both cancer cell lines. In general, the cationic bis-carbene complexes show higher stability and greater anticancer activity than their neutral mono-carbene analogues with IC50values in the high nanomolar range. Furthermore, to gain initial mechanistic insight, the interactions of these iridium(I)–NHC complexes with two model proteins, namely lysozyme and cytochrome c, were explored by HR-ESI-MS analyses. The different protein metalation patterns of the complexes can be roughly classified into two distinct groups. Those interactions give us a first idea about the possible mechanism of action of this class of compounds. Overall, our findings show that iridium(I)–NHC complexes represent very interesting candidates for further development as new metal-based anticancer drugs.
