Quaternization Reaction Research Articles

Synthesis, surface activities and aggregation properties of asymmetric Gemini surfactants.

A series of Gemini surfactants with an asymmetric structure (PKO 15-3(OH)-n; n = 12, 14 and 16) were synthesized through a simple two-step reaction consisting of a ring-opening reaction followed by a quaternization reaction. The surface tension measurements indicated that the surface activities of PKO 15-3(OH)-n were higher than those of traditional single-chain and symmetrical Gemini surfactants. The thermodynamic parameters obtained from electrical conductivity measurements showed that the micellization processes of PKO 15-3(OH)-n were spontaneous and entropy-driven. Transmission electron microscopy and dynamic light scattering measurements confirmed that PKO 15-3(OH)-n molecules with a higher asymmetric degree could form vesicles, in which surfactant molecules were interdigitated side-by-side in the vesicle membrane. The obtained results are not in accordance with those calculated from the critical packing theory, which can further complement the theory.

Optimization of invert emulsion oil-based drilling fluids performance through heterocyclic imidazoline-based emulsifiers

In this work six structurally related imidazoline oligomers based on the reaction of liner polyamine with saturated and unsaturated long alkyl chains (C18 oleic and stearic) fatty acids were prepared, followed by a quaternization reaction to produce new conventional and gemini imidazolinium quaternary salts. The chemical structures of prepared amphiphiles were confirmed via spectroscopic methods and elemental microanalysis, also, the prepared emulsifier’s characterization has been studied through static interfacial tension, visual and microscopic examination of prepared emulsification systems. The static interfacial tension measurements show a high ability to reduce interfacial tension values between diesel oil and water. The visual and microscopic examination gave evidence of a multilayer interface around emulsion particles and an increase of emulsion droplets size as a function of time with acceptable emulsion stability and phase separation. For both oil-based mud cost and diesel oil toxicity, this article brings to light many important aspects of designing new emulsifiers for low toxicity invert emulsion muds with lower diesel oil content. The prepared emulsifiers were mixed to be investigated and evaluated as primary emulsifiers package to formulate the invert emulsion oil-based muds (IEOBMs). The electrical stability, rheological properties, and filter loss were evaluated before and after hot roller aging and compared with the reference mud sample formulated from the commercial-grade emulsifiers. The experimental investigations conducted based on the Herschel-Bulkley rheological model showed good rheological behavior compared to the reference mud sample, high resistance to the deformation that occurred to prepared mud systems due to hot roller aging, good electrical stability, and high pressure-high temperature filtration loss values.

Enhanced Hydroxide Conductivity and Dimensional Stability with Blended Membranes Containing Hyperbranched PAES/Linear PPO as Anion Exchange Membranes.

A series of novel blended anion exchange membranes (AEMs) were prepared with hyperbranched brominated poly(arylene ether sulfone) (Br-HB-PAES) and linear chloromethylated poly(phenylene oxide) (CM-PPO). The as-prepared blended membranes were fabricated with different weight ratios of Br-HB-PAES to CM-PPO, and the quaternization reaction for introducing the ionic functional group was performed by triethylamine. The Q-PAES/PPO-XY (quaternized-PAES/PPO-XY) blended membranes promoted the ion channel formation as the strong hydrogen bonds interconnecting the two polymers were maintained, and showed an improved hydroxide conductivity with excellent thermal behavior. In particular, the Q-PAES/PPO-55 membrane showed a very high hydroxide ion conductivity (90.9 mS cm−1) compared to the pristine Q-HB-PAES membrane (32.8 mS cm−1), a result supported by the morphology of the membrane as determined by the AFM analysis. In addition, the rigid hyperbranched structure showed a suppressed swelling ratio of 17.9–24.9% despite an excessive water uptake of 33.2–50.3% at 90 °C, and demonstrated a remarkable alkaline stability under 2.0 M KOH conditions over 1000 h.

Janus Surface Micelles on Silica Particles: Synthesis and Application in Enzyme Immobilization.

In these years, synthesis and applications of Janus structures have aroused great interest for large-scale applications in chemistry and materials science. Up to now, Janus particles with different morphologies and different functionalities have been synthesized in solutions, but the synthesis of Janus particles on solid surfaces has not been touched. In this research, Janus surface micelles (JSMs) are fabricated on the surfaces of silica particles by polymerization induced surface self-assembly (PISSA) approach, and the JSMs are used for enzyme immobilization. Usually, enzyme immobilization should be able to optimize the performance of the immobilized enzymes, and an ideal immobilization system must offer protection to the immobilized enzyme with retained bioactivity. Herein, it is demonstrated that JSMs on silica particles can be used as an ideal platform for the immobilization of enzymes. To prepare JSMs, poly(2-(dimethylamino) ethyl methacrylate) macro chain transfer agent (PDMAEMA-CTA) brushes on silica particles and poly(di(ethylene glycol) methyl ether methacrylate) macro CTA (PDEGMA-CTA) are employed in reversible addition-fragmentation chain transfer dispersion polymerization of styrene. After polymerization, JSMs with polystyrene cores and PDMAEMA/PDEGMA patches on the surfaces are prepared on silica particles. After quaternization reaction, the quaternized PDMAEMA patches are used for the immobilization of enzymes. Experimental results turn out that enhanced bioactivities of the immobilized enzymes are achieved and the enzyme molecules are well protected by surface Janus structures.

Hyperbranched Poly(Glycidol)‐Grafted Silica Nanoparticles for Enhancing Li‐Ion Conductivity of Poly(Ethylene Oxide)

AbstractSilica nanoparticles bearing hyperbranched polyglycidol (hbP) grafts are synthesized and blended with poly(ethylene oxide) (PEO) for the fabrication of composite solid polymer electrolytes (SPEs) for enhancing Li‐ion conductivity. Different batches of hbPs are prepared, namely, the 5th, 6th, and 7th with increasing molecular weights using cationic ring‐opening polymerization and grafted the hbPs onto the silica nanoparticles using quaternization reaction. The effect of end functionalization of hbP‐grafted silica nanoparticles with a nitrile functional group (CN–hbP–SiO2) on the ionic conductivity of the blends with PEO is further studied. High dipole moments indicate polar nature of nitriles and show high dielectric constants. Among all the hbPs, the 6th‐batch CN–hbP–SiO2 nanoparticles exhibit better ionic conductivity on blending with PEO showing ionic conductivity of 2.3 × 10−3 S cm−1 at 80 °C. The blends show electrochemical stability up to 4.5 V versus lithium metal.

Synthesis, Characterization, and Computational Chemical Study of Aliphatic Tricationic Surfactants as Corrosion Inhibitors for Metallic Equipment in Oil Fields.

Aliphatic tricationic surfactants were prepared by the esterification reaction, followed by a quaternization reaction to protect oil well facilities from corrosion problems. Microelemental analysis and Fourier transform infrared and 1H NMR spectroscopic techniques were performed to explore the obtained motifs. The performance of these amphiphiles as inhibitors for metallic S90 steel corrosion in formation water was investigated through electrochemical tests (potentiodynamic polarization and electrochemical impedance spectroscopy). The results revealed significant inhibition effectiveness improvement with increasing concentrations of these amphiphiles. Its maximum inhibition efficiency reaches 93.07% at 250 ppm for the compound (AED). Potentiodynamic polarization graphs demonstrated that tricationic amphiphiles behave as mixed-type inhibitors. In addition, the adsorption of the tricationic surfactant at the S90 steel surface followed Langmuir isotherm. Atomic force microscopy revealed that a protective layer formed at the surface of S90 steel caused the inhibition of corrosion. During the inhibition procedure of S90 steel corrosion, theoretical research has been performed to validate electrochemical experiments and to clearly demonstrate the mechanism of these amphiphiles. Finally, quantum chemical calculations were calculated to achieve the justification for the obtained empirical results.

As-Synthesized Oleic Amido Propyl Betaine Surfactant Mixture and the Effect on the Crude Oil–Seawater Interfacial Tension

As-synthesized oleic amido propyl betaine surfactant mixture was developed through a slight modification of a conventional two-step betaine synthesis process of amidation and quaternization reactions. This method is a “direct formulating through synthesis” to achieve a targeted interfacial property (interfacial tension or IFT) of the as-synthesized surfactant. Oil–water IFT was measured in the crude oil–seawater system at 96 °C. The result showed that the as-synthesized surfactant was able to reduce crude oil–seawater IFT to the ultra-low level (<0.01 mN/m). As the finding emerged, the investigation was conducted to identify the elements that would bring the characteristic of ultra-low IFT. The characterization of the surfactant using FTIR, TG-IR, and HPLC suggested that unreacted materials associated with the surfactant remained, such as the carryover of a fatty amide from the intermediate process, residues of N, N trimethylene dimethylamine and sodium chloride as a by-product, and the important newly formed sodium oleate compound that was inadvertently generated via the reaction. The performance of the as-synthesized in seawater condition has been verified and the surface tension plot shows the lowest surface tension point at 0.05 wt.% concentration before developing a plateau region at higher surfactant concentration, indicating that the formation of surfactant micelles has been interrupted by the presence of other components in the solution. The dynamic IFT test performed on the as-synthesized product revealed that it was still able to reduce the crude oil–seawater IFT to an ultra-low level, despite the multiple undesirable components in the surfactant. IFT as low as 3.4 × 10−4 mN/m for the specific seawater and crude oil composition was obtained at a temperature of 96 °C.

Sensitive Determination of Imatinib Mesylate in Human Plasma Using DABCO-Based Ionic Liquid-Modified Magnetic Nanoparticles

In this research, new DABCO-based ionic liquid-modified Fe3O4 nanoparticles (NPs) were synthesized by the quaternization reaction. Modified magnetic NPs were characterized by different techniques. The functionalized magnetic NPs were utilized as a novel sorbent for magnetic SPE of imatinib mesylate (IMA) from human plasma samples followed with UPLC–MS–MS. Effective parameters on the extraction of IMA were studied by three-level Box–Behnken experimental design under response surface methodology. Under the optimized conditions, the proposed method was validated based on the principles of Guidance for Industry Bioanalytical Method Validation by the U.S. Food and Drug Administration. The linearity of the developed method was achieved within the range of 0.7–2500 ng mL−1. The LOD and lower limit of quantification were 0.68 and 0.21 ng mL−1, respectively. Satisfactory extraction recovery values ranged from 93 to 102% for human plasma samples with relative standard deviation values lower than 5.9%. The proposed analysis method was sensitive, efficient, rapid, and practical for the determination of IMA in biological samples.

Tripropyl Chitosan Iodide-Based Gel Polymer Electrolyte as Quasi Solid-State Dye Sensitized Solar Cells

Electrolyte as one of the major components in dye sensitized solar cells (DSSCs) plays an important role in dye regeneration and as the inner charge carrier transport between electrodes. Gel polymer electrolyte is a potential alternative to liquid electrolytes which suffer of leakage and solvent evaporation. In this present research, functionalization of chitosan by the quaternization reaction of chitosan with iodopropane forming tripropyl chitosan iodide is proposed for the preparation of gel polymer electrolyte. Tripropyl chitosan iodide was characterized by nuclear magnetic resonance spectroscopy (NMR), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Four different polymer electrolytes were tested at different compositions in presence of iodide/triiodide redox salt and imidazolium ionic liquid in DSSCs configurations. The results show that the gel polymer electrolyte containing the tripropyl chitosan iodide in presence of 1-propyl-3-methylimidazolium iodide ionic liquid showed better performance with power conversion efficiency of 0.415% as compared to the gel polymer electrolyte film without ionic liquid with power conversion efficiency of 0.075%. The results shown the synergistic effects of the polycationic tripropyl chitosan iodide with the ionic liquid 1-propyl-3-methylimidazolium iodide on the photovoltaic performance.

Imidazolium functionalized poly(vinyl alcohol) membranes for direct methanol alkaline fuel cell applications

AbstractIn this study, imidazolium functionalized poly(vinyl alcohol) (PVA) was synthesized by acetalization and direct quaternization reaction. Afterwards, composite anion exchange membranes based on imidazolium‐ and quaternary ammonium‐ functionalized PVA were used for direct methanol alkaline fuel cell applications. 1H NMR and Fourier transform infrared spectroscopy data indicated that imidazole functionalized PVA was successfully synthesized. Inductively coupled plasma mass spectrometry data demonstrated that the imidazolium structure was efficiently obtained by direct quaternization of the imidazole group. Composite anion exchange membranes were fabricated by application of the functionalized PVA solution on the surface of porous polycarbonate (PC) membranes. Fuel cell related properties of all prepared membranes were investigated systematically. The imidazolium functionalized composite membrane (PVA‐Im/PC) exhibited higher ionic conductivity (7.8 mS cm−1 at 30 °C) despite a lower water uptake and ion exchange capacity value compared to that of quaternary ammonium. In addition, PVA‐Im/PC showed the lowest methanol permeation rate and the highest membrane selectivity as well as high alkaline and oxidative stability. Dynamic mechanical analysis results reveal that both composite membranes were mechanically resistant up to 107 Pa at 140 °C. The superior performance of imidazolium functionalized PVA composite membrane compared to quaternary ammonium functionalized membrane makes it a promising candidate for direct methanol alkaline fuel cell applications. © 2020 Society of Chemical Industry

Synthesis and properties of dications-containing poly(aryl ether sulfone) anion exchange membranes

Since the 21st century, energy and environmental issues have become the focus of global attention. Traditional fossil energy resources such as oil and natural gas are drying up. Meanwhile, a large number of harmful gases and other pollutants would be produced in the use of traditional energy, which has a serious damage to the environment and climate. With the rapid increase of energy consumption and the need of environmental protection, the demand for clean and efficient energy is growing. Fuel cell (FC) is considered as one of the most promising energy conversion technologies that can replace conventional fossil fuels, and it is also an important choice in the use of hydrogen, methanol, ethanol and other renewable energy. As a new energy with great potential, FC can reduce the energy crisis and environmental pollution effectively by directly converting the chemical energy of the external input fuel into electrical energy and continuously supplying power to the outside. Ion exchange membrane (IEM) is an important component of FC, which is responsible for transferring ions and forming a complete FC circuit. According to the types of conducting ions, IEM can be divided into proton exchange membrane (PEM) and anion exchange membrane (AEM), which are applied to proton exchange membrane fuel cell (PEMFC) and alkaline anion exchange membrane fuel cell (AAEMFC), respectively. Compared with PEMFC, AAEMFC has the advantages of using non noble metal catalyst, high electrode reaction reactivity, and low fuel purity requirements and so on. However, the commercial AEM with organic cations often has low ionic conductivity and poor alkali and dimensional stability, which seriously hinders its development and application in AAEMFC. Therefore, it is urgent to design and develop new high-performance AEM materials. In order to improve the conductivity, alkali stability and dimensional stability of AEMs, a novel reactive bisphenol monomer with pendant dimethylphenoxybenzene group, 1,1-bis (4-hydroxyphenyl)-1-(4-(3,5-dimethylphenoxy) phenyl) phenyl-2,2,2-trifluoroethane ( 2 ), was synthesized based on molecular design using 4-fluoro-2,2,2-trifluoroacetophenone, 3,5-dimethylphenol and phenol as starting materials by a two-step organic reaction. Then, two series of poly(aryl ether sulfone) anion exchange membranes (2-PAES-QA- xx and 2-PAES-Im- xx ) with comb structure were prepared through aromatic nucleophilic copolycondensation, bromination and quaternization reaction based on monomer 2 . The structures of the active bisphenol monomer, the poly(aryl sulfone) containing methyl groups, the brominated poly(aryl ether sulfone)s and the ionized polymers were characterized systematically by nuclear magnetic resonance spectroscopy, respectively. The water uptake, swelling ratio, ionic conductivity, thermal stability, mechanical properties, and alkaline resistance stability of the prepared 2-PAES-QA- xx and 2-PAES-Im- xx membranes were studied in detail. The relationship between the structure and properties of different types of AEMs is further compared. The obtained AEMs showed good overall performance, and the OH– conductivity of these membranes at 60°C is 35.9–51.6 and 32.6–44.9 mS/cm, respectively. The IEC values of the representative 2-PAES-QA-60 and 2-PAES-Im-60 maintained at 79.7% and 88.5% of the initial values after immersion in 4 mol/L NaOH at 80°C for 336 h, respectively. This work provides a new strategy for the design and preparation of comb-type AEM materials.

The Quaternization Reaction of 5-O-Sulfonates of Methyl 2,3-o-Isopropylidene-β-D-Ribofuranoside With Selected Heterocyclic and Aliphatic Amines.

The synthesis of N-((methyl 5-deoxy-2,3-O-isopropylidene-β-D-ribofuranoside)-5-yl)ammonium salts are presented. To determine the effect of the nucleophile type and outgoing group on the quaternization reaction, selected aliphatic and heterocyclic aromatic amines reacted with: methyl 2,3-O-isopropylidene-5-O-tosyl-β-D-ribofuranoside or methyl 2,3-O-isopropylidene-5-O-mesyl-β-D-ribofuranoside or methyl 2,3-O-isopropylidene-5-O-triflyl-β-D-ribofuranoside were performed on a micro scale. High-resolution 1H- and 13C-NMR spectral data for all new compounds were recorded. Additionally, the single-crystal X-ray diffraction analysis for methyl 2,3-O-isopropylidene-5-O-mesyl-β-D-ribofuranoside and selected in silico interaction models are reported.

Biological properties of novel polysuccinimide derivatives synthesized via quaternary ammonium grafting

Two novel polysuccinimide (PSI) derivatives with antibacterial properties were synthesized by the reaction of polysuccinimide with different quaternary ammonium salts with an active terminal group. 4-bromobutyl-quinolinium bromide and 4-bromobutyl-benzalkonium bromide were synthesized from a quaternization reaction between 1,4-dibromobutane and a tertiary amine (quinoline and N, N-dimethylbenzylamine). These ammonium salts with a bromide end group were chemically grafted along the polysuccinimide chains by quaternization of the nitrogen atoms of PSI. The chemical structures of these PSI derivatives were characterized by 1H NMR analysis and FT-IR spectra. Thermal stability of these macromolecules was studied by thermo-gravimetric analysis. Antibacterial activity against E. coli strains was determined by the minimum inhibitory concentration and the minimum bactericidal concentration. In all the cases, it was possible to grant antibacterial properties to the polysuccinimide derivatives. Finally, hemolysis and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays were performed. PSI derivatives caused a lightly hemolytic effects on isolated human erythrocytes and murine fibroblast cell line, decreasing the cell proliferation of cancer cervical and breast cell lines.

Kinetic Investigations of Quaternization Reactions of Poly[2‐(dimethylamino)ethyl methacrylate] with Diverse Alkyl Halides

AbstractKinetic investigations of the quaternization reactions of poly[2‐(dimethylamino)ethyl methacrylate] (PDMAEMA) with alkyl halides (1‐iodobutane, 1‐iodoheptane, and 1‐iododecane) are carried out at different temperatures. For this purpose, a PDMAEMA (Mn = 17.8 kDa, Ð = 1.35) synthesized via reversible addition fragmentation chain transfer polymerization is utilized. The progress of the quaternization reactions is followed by proton nuclear magnetic resonance. As expected, the rate of quaternization is higher with increasing temperature. The experimental data are used to determine the following kinetic parameters: order of the reaction, Arrhenius' pre‐exponential factor, and activation energy. To the best of knowledge, this is the first contribution that provides detailed kinetic data of the quaternization reactions on PDMAEMA.

Film Properties and Antimicrobial Efficacy of Quaternized PDMAEMA Brushes: Short vs Long Alkyl Chain Length.

Quaternized poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) brushes bearing quaternary ammonium groups of different alkyl chain lengths (ACLs) were prepared and assessed as biocidal coatings. For the synthesis of the antimicrobial brushes, first well-defined PDMAEMA chains were grown by surface-initiated atom transfer radical polymerization on glass and silicon substrates. Next, the tertiary amine groups of the polymer brushes were modified via a quaternization reaction, using alkyl halides, to obtain the cationic polymers. The polymer films were characterized by Fourier-transform infrared spectroscopy, ellipsometry, atomic force microscopy, and water contact angle measurements. The effect of the ACL of the quaternary ammonium groups on the physicochemical properties of the films as well as the contact killing efficiency of the surfaces against representative Gram-positive and Gram-negative bacteria was investigated. A hydrophilic to hydrophobic transition of the surfaces and a significant decrease of the degree of quaternization of the DMAEMA moieties was found upon increasing the ACL of the quaternization agent above six carbon atoms, allowing the wettability, the thickness, and the pH-response of the brushes to be tuned via a facile postpolymerization, quaternization reaction. At the same time, antimicrobial tests revealed that the hydrophilic polymer brushes exhibited enhanced bactericidal activity against Escherichia coli and Bacillus cereus, whereas the hydrophobic surfaces showed a significant deterioration of the in vitro bactericidal performance. Our results elucidate the antimicrobial action of quaternized polymer brushes, dictating the appropriate choice of the ACL of the quaternization agent for the development of coatings that effectively inhibit biofilm formation on surfaces.

β-Cyclodextrin-derived Room Temperature Macromolecular Ionic Liquids by PEGylated Anions.

A series of cyclodextrin-derived room temperature macromolecular ionic liquids carrying rather low glass transition temperatures of -20 to -40 °C are synthesized via sequential esterification, quaternization, and anion metathesis reactions. In addition to being ionic in nature, they are viscous liquids at room temperature with more fluidic behavior at elevated temperatures. They serve as a solvent for organic dyes or iodine separation via a liquid-liquid extraction approach. This strategy is useful for the development of various sugar (macro)molecule-based functional ionic liquids as well as macromolecular ionic liquids.

Novel trimeric cationic pyrdinium surfactants as bi-functional corrosion inhibitors and antiscalants for API 5L X70 carbon steel against oilfield formation water

Three trimeric cationic pyridinium surfactants (APMC 6 , APMC 12 and APMC 18 ), were synthesized via esterification reaction, followed by a quaternization reaction, and characterized by micro-elemental analysis, FTIR, and 1 HNMR spectroscopy. Surface-active parameters for APMC compounds were investigated using surface tension measurements. The critical micelle concentration values declined as a function of the alkyl chain length. The corrosion inhibition performance of these surfactants was studied on API 5L X70 carbon steel against oilfield formation water as corrosive medium by various electrochemical techniques. The results indicated that APMC surfactants showed superior corrosion inhibitive activity, as the inhibition efficiency (%I.E.) was up to 94% for APMC 18 . Atomic force microscopy confirmed the creation of a protective layer on the carbon steel surface. Furthermore, the anti-scaling aspects of APMC compounds were investigated using static scale precipitation technique. The data revealed that the scale inhibition performance elevated by increasing the dosage of APMC compounds. Both anti-corrosion and anti-scaling results supported the potential multifunctional use of APMC compounds against corrosion and scale problems in formation water. Finally, quantum chemical calculations and Monte Carlo simulations were computed to fulfill a rationale of the obtained experimental data. • Three trimeric cationic surfactants (APMC) were synthesized and characterized. • APMC surfactants were good mixed-type corrosion inhibitors for X70 steel protection. • APMC surfactants were good antiscalant against scale tenable formation water. • AFM surface examination confirms the adsorption of APMC surfactants on X70 steel. • Theoretical insilico calculations showed good agreement with experimental data.

Eco-friendly quaternization of nicotinamide and 2-bromoacetophenones in deep eutectic solvents. Antifungal activity of the products

Most organic solvents used in quaternization reactions are volatile, hazardous, toxic and form by-products, thus inducing health issues and pollution. Deep eutectic solvents are greener alternatives, but they have not been tested yet in the quaternization reaction. Here we propose eutectic solvents in the quaternization reaction of nicotinamide with substituted 2-bromoacetophenones. The reaction was performed at 80 °C by three synthetic approaches: conventional during 2–6 h, microwave during 20 min and ultrasonic during 3 h. The highest yields of about 98% were obtained by microwave. The most suitable eutectic solvents were choline chloride with either urea, oxalic or levulinic acid. The use of deep eutectic solvents has several advantages: environmental benignity, biodegradability, easy purification and simple preparation. All tested compounds showed antifungal activities against Botrytis cinerea, Colletotrichum acutatum, Alternaria radicina and Fusarium graminearum at 10 and 100 µg/mL.

Porosity-Induced Selective Sensing of Iodide in Aqueous Solution by a Fluorescent Imidazolium-Based Ionic Porous Framework.

Developing a chemosensor for rapid, sensitive, and visual detection of iodide (I-) by a simple synthetic strategy is still challenging. Herein, we report a highly efficient iodide sensor by simply introducing ionic imidazolium groups into the porous network. This sensor, that is, a fluorescent ionic porous framework (IPF), was prepared by the quaternization reaction of octa((benzylchloride)ethenyl)silsesquioxane and 1,4-bis(1H-imidazole-1-yl)benzene and exhibited moderate porosity with a Brunauer-Emmett-Teller surface area of 379 m2 g-1 and blue fluorescence when excited by UV light. The IPF suspension in water can detect I- with high sensitivity and selectivity among various anions and quick response by fluorescence quenching. In contrast to no response toward I- by the linear model compound and the enhanced sensing performance with an increment of porosity, this finding indicates that the porosity of IPF is important for the detection of I- and an inducement of the sensing process. A fluorescent paper sensor was further developed, which shows high efficiency for the visual detection of I- similar to the abovementioned sensor, suggesting its potential in convenient and on-site sensing of I-. In addition, the paper sensor is recyclable with a remarkable fluorescence resuming ratio of 83% after 10 times cycle detection. Moreover, the developed sensor is used for the analysis of real samples. This work represents the first example of the detection of I- by an ionic porous polymer. Compared with conventional iodide sensors, the present sensor does not require unique structures to form the pseudocavity during sensing I- and can easily achieve high efficiency by incorporating ionic hydrogen bond donors into the porous network, indicating the importance of porosity and the feasibility of replacing the pseudocavity with a real cavity (or pore). More iodide sensors with high efficiency can be designed and fabricated by this novel and simple strategy.

Synthesis and biological evaluation of some novel 1‐alkyl‐3‐methylimidazolium carboxylate ionic liquids as potential antifungal agents

AbstractIn an effort to discover lead compounds that may be of importance as potent antifungal agents, a series of novel 1‐alkyl‐3‐methylimidazolium carboxylate ionic liquids were efficiently synthesized through a solvent‐free ultrasound‐assisted quaternization reaction of 1‐methylimidazole and alkyl bromides RBr (R = hexyl, octyl) followed by an anion exchange process with selected carboxylate anions (cinnamate, salicylate, crotonate, and oxalate). Quantitative yields obtained were in the range of 86–94%. Structure characterization was done using FT‐IR, 1H‐NMR, and 13C‐NMR spectroscopic techniques. All the synthesized compounds showed in vitro antifungal activity against the fungus Candida albicans with the minimum inhibitory concentrations found to be less than or equal to 1%. Preliminary cytotoxicity assays (trypan blue exclusion and MTT) were performed on all ionic liquids and findings revealed higher lymphocyte viability in 1‐hexyl‐3‐methylimidazolium carboxylate ionic liquids than in 1‐octyl‐3‐methylimidazolium counterparts. No extensive toxicity effect was observed with the carboxylate anion variation. Among the tested compounds, 1‐hexyl‐3‐methylimidazolium crotonate and 1‐hexyl‐3‐methylimidazolium oxalate exhibited the lowest cytotoxicity in the trypan blue exclusion and MTT assays, respectively. Together, our results highlight the potential of carboxylate‐based ionic liquids in the development of next‐generation antifungal drugs.