Carbon-carbon Cross-coupling Reactions Research Articles

Immobilization of Schiff base-Pd complex in mesoporous silica KIT-6 channels: A novel, green, recyclable, and highly versatile mesoporous catalyst for the carbon-carbon cross-coupling reaction

In this study, we developed an efficient and novel nanocatalyst by immobilizing Schiff base-Pd complex inside mesoporous silica KIT-6 channels, which were successfully synthesized by using a simple procedure. The catalytic activity of KIT-6@Schiff base-Pd was investigated in the synthesis of a wide variety of biphenyl derivatives. The N2 adsorption–desorption isotherms indicated the excellent Brunauer–Emmett–Teller surface area for KIT-6@Schiff base-Pd of 121.65 m2/g. The chemical and physical properties of raw and modified samples (KIT-6@Schiff base-Pd) were characterized based on Fourier transform-infrared spectra, thermogravimetric analysis, energy-dispersive X-ray spectroscopy, N2 adsorption–desorption, scanning electron microscopy, X-ray elemental mapping, and X-ray diffraction analyses. We found that the synthesized catalyst could be recovered and reused up to four times.

Using Atomic Layer Deposition (ALD) to Immobilize Molecular Catalysts on Solid Powder Supports

While homogeneous molecular catalysts are valued for their high reaction specificity, they are not as easily recoverable at industrial scales as heterogeneous catalyst powders that can be rapidly separated from the reaction solution. Here, we will discuss a new approach using atomic layer deposition (ALD) to immobilize molecular catalysts onto heterogeneous powder supports to achieve this combination of selectivity and recoverability. In this presentation, we demonstrate applicability using a non-noble metal (nickel) molecular catalyst to do Suzuki carbon-carbon cross-coupling reactions. Due to extremely short catalyst lifetimes caused by dimerization, this catalyst exhibits limited catalytic reactivity under homogeneous conditions. However, when heterogenized and immobilized, product yields of over 90% can be achieved in aqueous conditions, and the catalytic activity is preserved through over five hundred recovery and wash cycles. Following this work, we will also report on how modification of the ALD surface chemistry and number of ALD cycles affect catalytic performance.

Synthesis of 5-membered Heteroaryl-substituted Benzyloxy-benzaldehydes by the Suzuki-Miyaura Coupling Reaction

Abstract: In medicinal chemistry, benzyloxy-benzaldehyde is a valuable intermediate, to which the attachment of a five membered heterocycle may be advantageous from the point of view of drug design. The starting iodo-benzyloxy-benzaldehydes were synthesized by the O-benzylation of o-, m- and p-hydroxybenzaldehydes with 2-, 3- and 4-iodobenzylbromides in refluxing acetone or acetonitrile in the presence of potassium carbonate and potassium iodide. Starting from the corresponding iodo-benzyloxy-benzaldehydes, the Suzuki-Miyaura carbon-carbon cross-coupling reaction was utilized to get five membered heteroaryl-substituted benzyloxy-benzaldehydes. Various methods for Suzuki cross-coupling were studied. The applied boronic acids were 2- and 3-thiophene-boronic acids, as well as 2- and 3-furan-boronic acids. The reactions were followed by TLC and HPLC-UV-MS analysis. The products were purified by column chromatography. The original Suzuki method comprising NaOEt/EtOH, tetrakis(triphenylphosphine)palladium, in toluene was applied only in a few cases, resulting in poor yields. In several cases, the Suzuki coupling of substituted aryl iodides with 2-furanboronic acid failed to result in the formation of the expected products using the palladium acetate/tri(o-tolyl)phosphine/aqueous tripotassium phosphate/dimethoxyethan system. But reacting 3-thiophene-boronic acids with the corresponding iodo-benzyloxybenzaldehydes, this method afforded the products in 76-99 % yields. The more powerful tetrakis(triphenylphosphine)palladium/ aqueous cesium carbonate/dimethylformamide system seemed to be more successful in cases of 2-thiophene boronic acid as well as 2- and 3-furan-boronic acids, providing the desired products in 75-93% yield. Twenty-six new compounds were synthesized.

Magnetically Recoverable Nanoparticulate Catalysts for Cross-Coupling Reactions: The Dendritic Support Influences the Catalytic Performance.

Carbon-carbon cross-coupling reactions are among the most important synthetic tools for the preparation of pharmaceuticals and bioactive compounds. However, these reactions are normally carried out using copper, phosphines, and/or amines, which are poisonous for pharmaceuticals. The use of nanocomposite catalysts holds promise for facilitating these reactions and making them more environmentally friendly. In the present work, the PEGylated (PEG stands for poly(ethylene glycol) pyridylphenylene dendrons immobilized on silica loaded with magnetic nanoparticles have been successfully employed for the stabilization of Pd2+ complexes and Pd nanoparticles. The catalyst developed showed excellent catalytic activity in copper-free Sonogashira and Heck cross-coupling reactions. The reactions proceeded smoothly in green solvents at low palladium loading, resulting in high yields of cross-coupling products (from 80% to 97%) within short reaction times. The presence of magnetic nanoparticles allows easy magnetic separation for repeated use without a noticeable decrease of catalytic activity due to the strong stabilization of Pd species by rigid and bulky dendritic ligands. The PEG dendron periphery makes the catalyst hydrophilic and better suited for green solvents. The minor drop in activity upon the catalyst reuse is explained by the formation of Pd nanoparticles from the Pd2+ species during the catalytic reaction. The magnetic separation and reuse of the nanocomposite catalyst reduces the cost of target products as well as energy and material consumption and diminishes residual contamination by the catalyst. These factors as well as the absence of copper in the catalyst makeup pave the way for future applications of such catalysts in cross-coupling reactions.

Mizoroki-Heck carbon-carbon cross-coupling reactions by water-soluble palladium (II) complexes in neat water

Water-soluble palladium complexes were synthesized, characterized, tested as (pre)catalyst for Mizoroki-Heck carbon-carbon cross-coupling reactions in water. Cross-coupling of aryl iodides and bromides with methyl and ethyl acrylates was achieved at 140 °C. When styrene was employed as the substrate excellent conversion to trans-stilbene was observed using 5 mol% catalyst loading in the presence of TBAB. The catalysts are versatile and can couple various substrates in a non-toxic and benign solvent. After extraction of the organic product the catalyst containing aqueous layer could be recycled twice with a significant drop in the aryl halide conversion after the third recycle. No catalyst poisoning was observed in the mercury poisoning experiments with both catalysts and this proves that both catalytic systems function as molecular homogeneous catalysts.

Ferrocenylimine Palladium (II) Complexes: Synthesis, Characterization and Application in Mizoroki-Heck and Suzuki-Miyaura Cross-Coupling Reactions

Carbon-carbon cross-coupling reactions are essential synthetic tools for synthesizing polymers, natural products, agrochemicals, and pharmaceuticals. Therefore, new catalysts that function with greater efficiency and functional group tolerance are being researched. We have prepared new ferrocenylimine monodentate N and P donor ligands and N^N and N^P bidentate chelating ligands (L1 to L4) employed in stabilizing palladium ions for application in Mizoroki-Heck and Suzuki-Miyaura cross-coupling reactions. The ferrocenylimine ligands were successfully synthesized by Schiff base condensation reactions of acetyl ferrocene with hydrazine monohydrate to afford ferrocenyl hydrazone (L1). Ligand L1 was further treated with aldehydes to give ferrocenyl(2-diphenylphosphino)imine (L3) and ferrocenyl(pyridyl)imine (L3), while phosphination of L1 with chlorodiphenylphosphine afforded L2. The ligands were used to prepare new palladium(II) complexes (C1 to C4) by complexation with [PdCl2(MeCN)2]. All the ligands and complexes were fully characterized using standard spectroscopic and analytical techniques, including 1H NMR and 13C NMR spectroscopy, FT-IR spectroscopy, mass spectrometry and elemental analysis. The complexes (C1 to C4) were tested for efficacies in catalyzing Mizoroki-Heck and Suzuki-Miyaura C-C cross-coupling reactions and proved to be suitable catalyst precursors. Ferrocenyl(2-diphenylphosphine)imino and ferrocenyl-methyl hydrazone palladium(II) complexes C2 and C3 showed the best activities at TONs of up to 201. The ferrocenyl palladium(II) (pre)catalysts demonstrated moderate activity in Mizoroki-Heck reactions involving substrates with substituents on the olefin and aryl halide (including 4-Cl, 4-CH3, -CO2Me and -CO2Et). Density Functional Theory was used to study the mechanism of the Mizoroki-Heck cross-coupling reactions and have led to confirmation of the widely accepted catalytic cycle. Catalyst precursors (C1 to C4) also displayed good activity and selectivity in Suzuki-Miyaura cross-coupling reactions, at 0.5 mol% catalyst loading, with good tolerance to functional groups present on the aryl halide and boronic acid substrates (such as 4-Cl, 4-CHO, 4-COOH, 3-NO2, 3,5-dimethoxy and 4-CH3).

Synthesis, Analytical Characterization and Anti-Diabetic Activity of Some Heterocycles of Quinazolin-4(3H)one

Aim: Novel quinazolin-4(3H)-one heterocycles were synthesized and assessed for their anti-diabetic activity. Non-enzymatic glycosylation of haemoglobin assay was carried out to identify their potential as anti-diabetic. The cyclization of quinazolinone-4(3H)-one heterocycles was achieved, whereas carbon-carbon cross coupling reactions were carried out using Sonogashira and Suzuki-Miyaura reaction conditions and characterized with analysis. This synthesis method afforded corresponding 2, 3 and 6 substituted quinazolin-4(3H)-ones (3a to 3m) with excellent yields.
 Methods: 2-Amino-6-bromobenzoic acid was used as a substrate which was converted to corresponding benzamide derivatives (1a-1b) by reaction with benzylamine or cyclohexylamine using acid-amine reaction, followed by cyclization and oxidation using suitable aldehyde in DMSO under microwave condition to give bromo substituted quinazolin-4(3H)-ones (2a-2c), which were cross coupled to suitable terminal alkyne with palladium catalyst as well as copper co-catalyst using Sonogashira condition to obtain desired (3a-3h) and suitable boronic acid with palladium catalyst using Suzuki-Miyaura condition to obtain desired (3i-3m). All synthesized compounds were characterized by FTIR, proton NMR, LC-MS analysis and evaluated for in vitro anti-diabetic activity using non-enzymatic glycosylation of haemoglobin assay.
 Results: Compounds 3m showed good inhibition of glycosylation of haemoglobin which in turn suggest good anti-oxidant potential on metabolism of glucose and hence lower glucose concentration. It showed IC50 value of 35.91±0.82 µg/mL which was comparable to the standard alpha tocopherol (34.47±0.87µg/mL).
 Conclusion: In-vitro non-enzymatic glycosylation of haemoglobin method is one of important assays to judge the control of diabetes. The haemoglobin present in RBCs has an affinity to bind with glucose. The greater the glucose level in blood, more amount of glucose-bound (called glycosylated) haemoglobin will be formed. Accordingly, presence of lower concentration of glycosylated haemoglobin is a sure guide to the lower concentration of glucose in the blood. Synthesized compounds (3a-3m) lower the blood glucose level and 3m has highest potential among those which can be further developed as potent anti-diabetic.

Synthesis, Drug Likeness and In-vitro Screening of Some Novel Quinazolinone Derivatives for Anti-Obesity Activity

Aim: A series of novel quinazolinone derivates was synthesized and assessed for their ability to inhibitory action on pancreatic lipase. The cyclization of quinazolinone-4(3H)-one derivatives was achieved, whereas carbon-carbon cross coupling reactions were carried out on cyclized quinazolinone-4(3H)-one. This synthesis method afforded corresponding 2, 3 and 6 substituted quinazolin-4(3H)-ones (3a to 3m) with moderate to high yields.
 Methods: Benzamide derivatives (1a-1b) were synthesized from anthranilic acid using acid-amine reaction, followed by cyclization using catalytic p-toluene sulfonic acid and oxidation using (diacetoxyiodo)benzene to give bromo substituted quinazolin-4(3H)-ones (2a-2b), which were cross coupled to suitable boronic acid using Suzuki-Miyaura condition to obtain desired compound (3a-3m). All synthesized compounds were characterized by FTIR, proton NMR, LC-MS analysis, checked for their drug likeness, absorption and evaluated for in vitro pancreatic lipase inhibition activity.
 Results: Analytical interpretation of all compounds with infrared, proton NMR and LC-MS spectroscopy confirmed their correct structure. All compounds (3a-3m) show good absorption and have reasonably good molecular properties except 3c and 3m which violate two criteria for Lipinski’s rule. Whereas, Compounds 3l and 3m showed IC50 value of 13.13±0.84 µg/mL and 13.80±1.27 µg/mL respectively comparable to the Orlistat (12.72±0.97µg/mL), a US FDA approved drug for the treatment of obesity.
 Conclusion: Pancreatic lipase is an important lipolytic enzyme, synthesized and secreted through pancreas, plays an important role in dietary trigycerol absorption and metabolism. Therefore, reducing fat absorption through pancreatic lipase inhibition is a promising strategy to treat obesity. Based upon our findings, compounds 3l and 3m can be further developed as potent anti-obesity agents.

Carbon-carbon cross-coupling reactions of organomagnesium reagents with a variety of electrophilic substrates mediated by iron catalysts

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Microwave-assisted Carbon-carbon and Carbon-heteroatom Cross-coupling Reactions in Organic Synthesis

Conventionally, the organic reactions are accomplished by conductive heating with an external heat source like an oil bath. On the contrary, since its inception, the application of microwave irradiation is growing as a suitable alternate heating method in organic synthesis. Microwave heating considerably reduces the reaction time without promoting any side reactions. The fundamental synthetic organic chemistry majorly deals with transition-metal-catalyzed C–C and C–heteroatom bond formation reactions. It is one of the most important methods in contemporary chemistry resulting in a tremendous increment in the applications of these reactions during the last few years. This field has been acknowledged with a number of Nobel Prizes during the last decade (2001, 2005 and 2010). A considerable effort has been done on the continuous development of new ligands and catalysts as well as an increased understanding of the mechanisms for the improvement of the reaction condition. This review focuses on some of the latest developments in the area of cross-coupling reactions aided by microwave irradiation.

Cu (Ii) Salen Complex@Kcc-1: A Recyclable Heterogeneous Catalyst in Carbon-Carbon Cross-Coupling Reaction

A Cu (II) Salen complex supported on KCC-1 (Cu(II) Salen complex@KCC-1) has been synthesized and characterized via XRD, FT-IR, TEM, and EDX. The synthesized catalyst was determined to be an effective heterogeneous catalyst for the coupling reaction of Suzuki-Miyaura. Cu (II) Salen @ KCC-1 complex can be separated and reused simply in the reaction mixture and reused several consecutive runs without a significant reduction in the performance of the catalyst. The development of a KCC-1-supported Cu catalyst is anticipating to be a promising system for carrying out heterogeneous catalytic reactions.

Pd-Guanidine@Boehmite: Chemoselective, Phosphine-Free and Practical Nanocatalyst in Carbon-Carbon Cross Coupling Reaction

Boehmite nanoparticles were synthesized via Al(NO3)3⋅9H2O and NaOH solution and then, an complex of Pd was fabricated on its surface (Pd-Guanidine@boehmite). This nanocatalyst was used as practical and recoverable nanocatalyst for the chemoselective C-C band formation such as Mizoroki-Heck and Suzuki–Miyaura reactions without phosphine ligands or inert atmosphere. This catalyst has been characterized by some analysis such as EDS, WDX, SEM, TGA, AAS, and BET. Also, obtained products from C-C coupling reactions were identified by NMR spectroscopy and melting points. This catalyst was recycled in described reactions without palladium leaching under reaction conditions.

Green Synthesis of Oxide-Supported Pd Nanocatalysts by Laser Methods for Room-Temperature Carbon-Carbon Cross-Coupling Reactions.

This work reports the design and development of a new class of highly active Pd nanocatalysts supported on substoichiometric oxides. These novel catalysts are generated by green laser synthesis methods to generate high-surface-area substoichiometric oxide nanoparticles followed by photoreduction in aqueous solutions to deposit highly active Pd nanocatalysts within the surface defects of the oxides. The laser methods eliminate the use of toxic chemicals, including hazardous solvents and chemical reducing agents, and allow efficient reduction of the Pd ions in aqueous solutions aided by the photogenerated electrons from the semiconductor support. The Pd catalysts incorporated within these oxides exhibit high activity for carbon-carbon bond-forming reactions. The Pd/TiO2 catalyst with 0.3 mol % Pd achieves 100% conversion in the reaction between bromobenzene and benzeneboronic acid to the biphenyl product within 240 minutes at room temperature without any external heating. With a catalyst loading of 0.3 mol % Pd in the microwave-assisted reaction between bromobenzene and benzeneboronic acid at 60 °C, 92 and 83% conversions to the biphenyl product are achieved within 5 min of reaction time using the Pd/TiO2 and Pd/ZnO catalysts, respectively. The results demonstrate a remarkable catalytic activity of the substoichiometric oxide-supported Pd catalysts with turnover frequencies (TOF, h-1) of 24 000, 10 000, and 3200 achieved under mirowave-assisted reactions at 60 °C for the 0.03 mol% Pd of the Pd/TiO2, Pd/ZnO, and Pd/ZrO2 catalysts, respectively. The high activity and good reusability of these nanocatalysts are attributed to the optimum catalyst-support interaction between the small Pd nanoparticles and the surface defects of the substoichiometric oxide support prepared by the laser vaporization-controlled condensation method.

An insight into the novel covalent functionalization of multi-wall carbon nanotubes with pseudopeptide backbones for palladium nanoparticles immobilization: A versatile catalyst towards diverse cross-coupling reactions in bio-based solvents

Materials functionalization with multicomponent reactions (MCRs) has grabbed a lot of attention nowadays due to the integration of outstanding features of MCRs with materials domains. Herein, we put the spotlight on the isocyanides and Meldrum’s acid-based MCRs route for the one-pot covalent functionalization of multi-wall carbon nanotubes (MWCNTs) which led to pseudopeptide-decorated MWCNTs with the ability to immobilized palladium nanoparticles and serve as a neoteric catalytic system. Characterization of the synthesized nanocatalyst was carried out by FT-IR, 1H NMR, XRD, SEM, TEM, EDX and TGA. The catalytic activities of the nanocatalyst for diverse carbon-carbon cross-coupling reactions were examined in bio-based solvents. The results showed the catalytic performance of the nanocatalyst for the formation of Csp2-Csp2, Csp-Csp2 and Csp-Csp bonds through homocoupling and intermolecular Ullmann, CH arylation, Mizoroki-Heck, Sonogashira and Glaser coupling reactions with considerable improvements in the yield, reaction times, bio-based media and chemoselectivity of the procedures. Additionally, this method demonstrated a high potential for recycling of heterogeneous catalysts by maintaining their initial performances without any evidence of the Pd leaching.

Recent Developments in Nanostructured Palladium and Other Metal Catalysts for Organic Transformation

Nanocatalysis is an emerging field of research and is applicable to nearly all kinds of catalytic organic conversions. Nanotechnology is playing an important role in both industrial applications and academic research. The catalytic activities become pronounced as the size of the catalyst reduces and the surface area-to-volume ratio increases which ultimately enhance the activity and selectivity of nanocatalysts. Similarly, the morphology of the particles also has a great impact on the activity and selectivity of nanocatalysts. Moreover, the electronic properties and geometric structure of nanocatalysts can be affected by polar and nonpolar solvents. Various forms of nanocatalysts have been reported including supported nanocatalysts, Schiff-based nanocatalysts, graphene-based nanocatalysts, thin-film nanocatalysts, mixed metal oxide nanocatalysts, magnetic nanocatalysts, and core-shell nanocatalysts. Among a variety of different rare earth and transition metals, palladium-based nanocatalysts have been extensively studied both in academia and in the industry because of their applications such as in carbon-carbon cross-coupling reactions, carbon-carbon homocoupling reactions, carbon-heteroatom cross-coupling reactions, and C-H activation, hydrogenation, esterification, oxidation, and reduction. The current review highlights the recent developments in the synthesis of palladium and some other metal nanocatalysts and their potential applications in various organic reactions.

Design and Synthesis of a Novel Banana-Shaped Functional Molecule via Double Cross-Coupling.

A novel banana-shaped molecule using 2,8-Dimethyl-6H,12H-5,11-methanodibenzo [b,f] [1,5]diazocine (Tröger’s base) as bent-core was synthesized via double Carbon-Carbon cross-coupling reaction. The double Sonogashira cross-coupling reaction was optimized by using Pd(PPh3)2Cl2 as catalyst, CuI as cocatalyst and diisopropylamine as base in place of triethylamine. The structure of this compound was confirmed by 1H-NMR, 13C-NMR, Fourier transform infrared (FT-IR) spectroscopy and mass spectrometry.

Synthesis of Dendrimer Assisted Co-Pd Bimetallic Nanoparticles and Catalytic Activity for Suzuki–Miyaura Coupling Reactions

Triazine-based dendrimer 2,4,6-tris(di-acetamido)-1,3,5-triazine encapsulated heterogeneous Co-Pd bimetallic nanoparticles (NPS) were prepared through sequential loading method from the dendrimer which was synthesized directly between the reaction of 2,4,6-triamino-1,3,5-triazine and acetyl chloride at room temperature about 2 hours. The physicochemical characteristics of Co-Pd bimetallic NPS were studied with the aid of EDX, XRD, TG& DSC techniques. The presence of cobalt was 55.75% and palladium was 9.40% of the mass of the 2,4,6-tris(di-acetamido)-1,3,5-triazine assisted Co-Pd Bimetallic NPs 4 observed from EDX analysis. The TG& DSC analysis curves indicated the thermal stability up to 320°C which is a very important steadiness key for catalytic effectiveness of the prepared Co-Pd Bimetallic NPs 4. The nano-shape FCC structure of Co-Pd bimetallic NPs was confirmed by XRD analysis. The average size of Co-Pd bimetallic NPs of 17.50 nm length was calculated through the Debye-Scherrer formula while TEM analysis showed the average particle size was 14.50 nm. The dendrimer was also analyzed by IR, ¹HNMR, ¹³CNMR and elemental analysis. The catalytic performance of these nanoparticles' catalyst was explored for C–C coupling reactions such as Suzuki–Miyaura at moderate reaction conditions whereas the reusing potential of the catalyst was evaluated without noticeable loss of activity for five successive runs. All the results of the analysis of this catalyst make it a cost-effective and highly active catalyst for the carbon-carbon cross-coupling reactions which are demand in chemical and pharmaceutical industries.

One-pot synthesis of new $N$-(1-methylpyridin-4(1$H)$-ylidene)amine ligands for palladium-catalyzed Heck coupling reaction

A series of new derivatives of N-(1-methylpyridin-4(1H)-ylidene)amines, [L1]-[L5], were synthesized and characterized by FTIR, NMR, MS, and XRD analysis. These targeted compounds were synthesized by the melt reaction between N-methylated-4-chloropyridinium triflate and corresponding amines (1-naphthyl amine, o-ansidine, 2-nitroaniline, p-ansidine, and cyclohexyl amine) followed by the addition of sodium hydride in dichloromethane in the same pot. These highly electron-donating N-(1-methylpyridin-4(1H)-ylidene)amine ligands considerably improve the catalytic activity of palladium acetate towards Heck-Mizoroki carbon-carbon cross-coupling reactions.

A domino desulfitative coupling and decarboxylative coupling of 3,4-dihydropyrimidine-2-thiones with copper(I) carboxylates

A novel and general carbon-nitrogen and carbon-carbon cross-coupling reaction between 3,4-dihydropyrimidine-2-thiones and copper(I) carboxylates were performed in the presence of palladium acetate. The copper(I) carboxylates act not only as desulfurative reagents but also as sources of carbon nucleophiles. A wide array of highly substituted and functionalized pyrimidines scaffolds were synthesized in good yields.

Highly Loaded Multi-Walled Carbon Nanotubes Non-Covalently Modified with a Bis-Imidazolium Salt and their Use as Catalyst Supports.

The surfaces of multi-walled carbon nanotubes (MWCNTs) were non-covalently modified using two bis-imidazolium dibromide derivatives having phenyl or pyrene groups. Due to the presence of the two pyrene groups the bis(pyren-1-ylmethylimidazolium) dibromide derivative was immobilised at a loading of about 15-16 wt %, whereas only <3 wt % of the phenyl derivative was immobilised. The presence of the two imidazolium cations helped the immobilisation of tetrachloropalladate ions after exchange with bromide ions. Tetrachloropalladate was used as pre-catalyst in several Suzuki-Miyaura carbon-carbon cross-coupling reactions in water or water/ethanol at 50 °C in only 0.1 mol % and compared with the non-supported pre-catalyst. The MWCNT-supported material was used in five consecutive cycles of the Suzuki-Miyaura reaction. Recycling using phenylboronic acid and 4-bromobenzaldehyde in water/ethanol was achieved with only a minor loss in activity. HRTEM images clearly showed the presence of the bis(pyren-1-ylmethylimidazolium) derivative on the sidewalls of MWCNTs.