Pyridinium Cations Research Articles

Measured relative complex permittivities for multiple series of ionic liquids

Presented in this paper are experimentally measured relative complex permittivities as a function of frequency for a representative range of ionic liquids, comprising 64 imidazolium, choline, phosphonium, ammonium, pyrrolidinium, pyridinium and piperidinium cations with a variety of anions. The measurement was conducted using a coaxial probe technique at room temperature from almost DC (0 Hz) to 18 GHz with a high level of accuracy. The real parts of the complex permittivities have been summarized in table format with both the real and imaginary parts presented as individual spectra for each ionic liquid. It is found that an increase in the molecular weight results in a decrease in overall permittivity and this is true over multiple series of ionic liquids. Additives such as water are shown to have a profound effect on the complex permittivity. The measured data is useful for a wide range of applications, such as electronic devices, chemical synthesis and materials.

Ecotoxicity evaluation towards Vibrio fischeri of imidazolium- and pyridinium-based ionic liquids for their use in separation processes

The non-volatility character of the ionic liquids makes them environmentally attractive to new separation processes development, but their water solubility emphasizes the importance of the study of their impact on the aquatic environment. The present work reports the toxicity of 24 imidazolium- and pyridinium-based ionic liquids through Vibrio fischeri inhibition basic test. The toxicity-structure relationship of the ionic liquids has been studied through the anion and cation core, the cation alkyl chain length, and the presence of functional groups on the cation alkyl chain. Ionic liquids whose chemical structure includes pyridinium cations, long cation alkyl chains, and bis(trifluoromethylsulfonyl) imide ([Tf2N]) anions present the highest toxicity. Finally, considering ionic liquids as potential solvents for the aromatic/aliphatic separation process, their toxicity has been compared to that of sulfolane, which is the current organic solvent used in this kind of process. Most of the studied ionic liquids can be classified as harmless or practically harmless; meanwhile, only four of them present a slightly or moderately toxicity, the same than that of sulfolane. The present study suggests that not only the atmospheric pollution would be decreased, but the aquatic impact as well by using ionic liquids as alternative solvents. Ionic liquids (ILs) stand as more environmentally friendly solvents in the petrochemical industry. Their toxicity towards Vibrio fischeri bacteria is lower than most of the “green” alternative deep eutectic solvents (DESs) and much lower than the current solvent, sulfolane.

Molybdenum complexes with citrate revisited. A mononuclear [MoVOCl4(H2O)]− ion as a new synthetic entry

Products of the reaction of a mononuclear molybdenum(V) compound, (PyH)5[MoVOCl4(H2O)]3Cl2, with citric acid (IUPAC name: 2-hydroxypropane-1,2,3-tricarboxylic acid, abbreviated as H4cit) were characterized by spectroscopic techniques and X-ray structure analysis. When the supply of oxygen was limited, molybdenum retained the initial oxidation state and a tetranuclear Mo(V) compound formed, (MeNC5H5)4[MoV4O8(cit)2]·2H2O (1) (MeNC5H5+ = N-methylpyridinium cation). Otherwise, oxidation of metal to +6 state took place resulting in {(C6H5)4P}[MoVIO2Cl(H2cit)] (3), (PyH)2[MoVIO2(H2cit)2]·Py (4), (PyH)4[{MoVIO2(Hcit)}2(µ2-O)]·2Py (5), (PyH)4[MoVI4O11(Hcit)2]·2H2O·1/2CH3OH (6) and (PyH)6[MoVI4O11(Hcit)2]Cl2·H2O·3/2CH3OH (7) (Py = pyridine, C5H5N; PyH+ = pyridinium cation, C5H5NH+). In one instance, (PyH)2[MoVOCl2(Hcit)]0.39[MoVIO2Cl(Hcit)]0.61·CH3CN (2), a compound that is a solid mixture of Mo(V) and Mo(VI) species was obtained. In all complexes, the citrate coordinated to molybdenum in a chelating manner with at least two oxygen atoms that belonged to deprotonated OH and α-carboxyl groups. In {MoVIO2}2+ species, the two trans positions of the Mo=O moieties were occupied with carboxylate oxygens. In order to assess stabilities of different orientations of citrate ligands with respect to Mo=O, the isomeric forms of [MoVIO2Cl(H2cit)]− and [MoVIO2(H2cit)2]2−, the anions of 3 and 4, were subjected to DFT calculations. Results reveal that the relative energies of isomers are close to one another. A particular orientation of citrate does not seem to have a determining impact. As the case of the [MoVIO2(H2cit)2]2− isomers, which gain stability by intramolecular hydrogen bonds, shows, other factors are at work. For the metal–metal bonded {MoV2O4}2+ compounds, comparison with the known complexes suggests that a concept of a preferential orientation of citrate, i.e., with the alkoxide oxygen situated at the site trans to Mo=O, is not valid.

Dual-band simultaneous lasing in MOFs single crystals with Fabry-Perot microcavities

Multi-band microlasers based on single microcrystalline materials with Fabry-Perot (F-P) cavities are critically and technologically essential. Here, we demonstrate simultaneous dual-band lasing output (615 and 685 nm) in metal-organic frameworks (MOFs) and organic dyes hybrid single crystals, which support F-P resonances. Through a two-step assembly strategy, two different types of cationic pyridinium hemicyanine dye molecules can be encapsulated into the channel pores of anionic bio-MOF-1-2Me successfully. In addition, the employment of the host-guest system significantly increases the dye loading, enhances luminescent efficiency, and diminishes the aggregation-caused quenching (ACQ) effect in the resultant MOFs/dye composites. This finding not only combines the characteristic of MOFs materials with excellent luminescent properties of organic dyes, but also points out a simple and promising strategy to design multi-band microlasers based on F-P mechanism, opening a low-cost avenue for the rational design of miniaturized lasers in the future.

Ionic liquids with superior protection for mild steel in acidic media: Effects of anion, cation, and alkyl chain length

The inhibiting effect of seven ionic liquids (ILs) with various anions, cations, and alkyl chain lengths on mild steel corrosion in acidic solution (1 M HCl) was demonstrated using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). ILs with different chain lengths such as 1-ethyl-3-methyl-imidazolium hexafluorophosphate (EMIMPF6), 1-methyl-3-pentyl-imidazolium hexafluorophosphate (PenMIMPF6), and 1-methyl-3-octyl-imidazolium hexafluorophosphate (OctMIMPF6) were examined. In addition, ILs with various anions such as 1-methyl-1-octyl-pyrrolidinium hexafluorophosphate (OctMpyrPF6), 1-methyl-1-octyl-pyrrolidinium thiocyanate (OctMpyrSCN), and 1-methyl-1-octyl-pyrrolidinium dicyanamide (OctMpyrN(CN)2) were considered. Furthermore, ILs with various cations such as 1-octylpyridinium hexafluorophosphate (OctpyPF6), OctMpyrPF6, and OctMIMPF6 were compared. Of all the ILs successfully synthesized in our laboratory, three of them were new: OctMpyrPF6, OctMpyrSCN, and OctMpyrN(CN)2. PDP experiments indicated that the investigated ILs were inhibitors of the mixed type. The adsorption of the studied ILs at the interface of the mild steel/electrolyte obeyed the Langmuir adsorption isotherm, which was also confirmed by SEM and attenuated total reflectance (ATR)-FTIR. The adsorption free energy (ΔG°ads) of these ILs showed negative values, which confirms their spontaneous physical adsorption. In comparing ILs with the same anion and cation, the IL OctMIMPF6, which had the longest alkyl chain, gave the best protection efficiency. The N(CN)2 anion showed better protection for mild steel than SCN and PF6. Imidazolium cation gave better inhibition than pyrrolidinium and pyridinium cations. SEM and ATR-FTIR analyses confirmed the strong adsorption of the studied ILs on the metal surface to form a protective film, which supports the electrochemical and the theoretical results.

Extraction and determination of pyridinium ionic liquid cations in environmental water samples by using strong cation exchange solid phase extraction and ion chromatography

ABSTRACTThis paper presents a novel analytical method for the determination of pyridinium ionic liquid cations in environmental water samples by ion chromatography coupled with solid phase extraction. The water samples were purified and enriched by a sulphonic acid extraction column, and then the impurities were washed with 10 mL water – 20% (v/v) acetonitrile solution and the analytes eluted with 0.5 mol L−1 phosphoric acid – sodium dihydrogen phosphate buffer solution – 55% methanol. The eluted analytes were determined by ion chromatography with 3.0 mmol L−1 methane sulphonic acid – 8% acetonitrile as the mobile phase and direct conductivity detection. Three pyridinium cations were completely separated in 20 min and the retention mechanism basically conforms to the ion exchange mode. The newly developed method has been successfully applied to the analysis of pyridinium cations in spiked environmental water samples, which provided satisfactory recoveries in the range of 98.8% to 100.0% with the relative standard deviations less than 2.8%. The concentration of 0.004 to 0.01 mg L−1 in water samples can be preconcentrated by this method. The method is accurate, reliable, simple and practical. This research provides a new reference for detecting ionic liquid cations in environmental water samples and studying the environmental risk assessment of ionic liquids.

Synthesis, characterization, ecotoxicity and biodegradability evaluations of novel biocompatible surface active lauroyl sarcosinate ionic liquids

Ionic liquids (ILs) based surfactants have been emerged as attractive alternatives to the conventional surfactants owing to their tailor-made and eco-friendly properties. Therefore, present study described the synthesis of nine new fatty amino acids based IL surfactants utilizing lauroyl sarcosinate anion and pyrrolidinium, imidazolium, pyridinium, piperidinium, morpholinium and cholinium cations for the first time. The synthesized surface active lauroyl sarcosinate ionic liquids (SALSILs) were characterized by 1H NMR, 13C NMR and TGA. Next, the surface tension and critical micellar concentrations were determined and compared with the surface properties of ILs based surfactants. Further, the toxicity and biodegradability of the synthesized SALSIILs were evaluated to confirm their safe and efficient process applications. The studies revealed that three out of nine synthesized SALSILs containing pyridinium cation have showed strong activity towards the tested microbial growth. The remaining six SALSILs met the biocompatible measures demonstrating moderate to low activity depends on the tested microbes. The alicyclic SALSILs containing morpholinium and piperidinium cations have demonstrated 100% biodegradation after 28 days of the test period. Overall, it is believed that the synthesized SALSILs could effectively replace the conventional surfactants in a wide variety of applications.

Synthesis and photodynamic activity of novel non-symmetrical diaryl porphyrins against cancer cell lines

Photodynamic therapy (PDT) of cancer uses photosensitizers (PS), a light source and oxygen to generate high levels of reactive oxygen species (ROS), that exert a cytotoxic action on tumor cells. Recently, it has been shown that mixed non-symmetrical diaryl porphyrins, with two different pendants, are more photodynamically active than symmetrical diaryl porphyrins.In the present study, we investigate the in vitro photodynamic effects of four novel non-symmetrical diaryl porphyrins, two of which bear one pentafluoro-phenyl and one bromo-alkyl (apolar) pendant, whereas the two others bear one pentafluoro-phenyl and one cationic pyridine pendant. The four compounds were tested in a small panel of human cancer cell lines, and their photodynamic activities were compared with that of m-THPC (Foscan), currently the most successful PS approved for clinical use in cancer PDT.The results of the cytotoxicity studies indicate that the two molecules bearing the cationic pendant are more potent in vitro than those with the apolar pendant, and that they are as potent as Foscan. To gain further insights into the mechanism of PS-induced phototoxicity, induction of apoptotic, autophagic and necrotic cell death, and generation of reactive oxygen species (ROS) were evaluated in cancer cells following exposure to the PSs and irradiation. The effect of the PSs on the migratory activity of the cells was also assessed.The data obtained from this work support a greater potency of diaryl porphyrins with a positive charge in inducing cell death, as compared to those with the bromo-alkyl pendant; most importantly, some of these novel compounds exhibit features that might make them superior to the clinically approved PS Foscan.

A dual-functional 3D coordination polymer as a luminescent sensor for acetone in an aqueous medium and detecting the temperature

A novel coordination polymer, {[Cd4(Ccbp)3(dpe)4·4H2O]·(ClO4)5·4H2O} (CP 1) (Ccbp = 3-carboxy-1-(3-carboxybenzyl)pyridin-1-ium, dpe = 1,2-di(pyridin-4-yl)ethane), was synthesized under hydrothermal conditions by a zwitterionic organic ligand and dipyridine ligand, and was fully characterized. This CP 1 with a pyridine cation basic skeleton can be used as the first potential dual-function luminescence sensing material for the selective, sensitive and recyclable sensing of acetone molecules in aqueous phase and for the quantitative detection of ultra-low temperatures of 10 to 70 K.

Two metal-carboxylate-azide coordination networks derived from 1,4-bis(3-carboxylatopyridinium-1-methylene)benzene: Synthesis, structure and properties

Betaine-type ligands are an attractive class of zwitterionic molecule, which have attracted considerable interest because they may not only keep the versatile coordination modes of carboxylate groups but also provide a new way to adjust the charge distribution of coordination polymers by cationic pyridinium groups. In this article, two coordination polymers composed of betaine-type ligand and azide anions, {[Co2(L)(N3)4]n·2H2O}n (1), [Zn(L)(N3)2]n (2) (H2L·2Cl = 1,4-bis(3-carboxylatopyridinium-1-methylene)benzene dichloride), have been synthesized. These compounds were characterized by IR spectroscopy, elemental analysis, thermogravimetric analysis and single-crystal X-ray diffraction. The X-ray diffraction crystal structure analysis reveals that the complex 1 is a twofold interpenetrating three-dimensional framework. The magnetic measure shows that complex 1 exhibits a ferromagnetic behavior at low temperature. Complex 2 displays a one-dimensional chain, which is further extended into a 3D framework through hydrogen bond and van der Waals interactions. The luminescence data of complex 2 shows the emission of a yellow luminescence. Remarkably, complexes 1 and 2 both exhibit a good photocatalytic activity for degradation of rhodamine B (RhB) under the simulated sunlight irradiation.

Ionic Liquids and Salts from Ibuprofen as Promising Innovative Formulations of an Old Drug.

Herein we report the synthesis of novel ionic liquids (ILs) and organic salts by combining ibuprofen as anion with ammonium, imidazolium, or pyridinium cations. The methodology consists of an acid-base reaction of neutral ibuprofen with cation hydroxides, which were previously prepared by anion exchange from the corresponding halide salts with Amberlyst A-26(OH). In comparison with the parent drug, these organic salts display higher solubility in water and biological fluids and a smaller degree of polymorphism, which in some cases was completely eliminated. With the exception of [C16 Pyr][Ibu] and [N1,1,2,2OH1 ][Ibu], the prepared salts did not affect the viability of normal human dermal fibroblasts or ovarian carcinoma (A2780) cells. Therefore, these ibuprofen-based ionic liquids may be very promising lead candidates for the development of effective formulations of this drug.

Assessing the dispersion of supported H3PW12O40 catalysts: No longer a hurdle thanks to in situ IR upon pyridine adsorption

Pyridine is since a long time used as an infrared (IR) molecular probe to characterize the acidity of solids, in particular of heteropolyacids (HPAs). The latter are metal-oxygen-clusters nowadays widely used in acid catalysis. Indeed, thanks to their exceptionally strong Brönsted acidity, they allow operating chemical reactions under significantly milder conditions than required by conventional catalysts. In the case of H3PW12O40, the most acidic Keggin-type HPA, it is well-known that the exposure to pyridine leads to an unusual IR spectrum. Indeed, the band at about 1540 cm−1 associated to the ν19b pyridinium ring stretch mode is split in two. Up to now, this phenomenon was studied with the only aim of understanding its origin, which was proposed to be a tunneling effect related to a frustrated rotation of the pyridinium cation within the solid bulk of H3PW12O40. Here, we demonstrate for the first time that it can actually be used as an analytical tool, namely to probe the degree of dispersion of supported H3PW12O40 units, a key parameter dictating their catalytic performance. We support H3PW12O40 on TiO2 P25 (hydrophilic) and TiO2 T805 (hydrophobic), so yielding samples with different degrees of dispersion, as qualitatively assessed through X-ray photoelectron spectroscopy. Through in situ Fourier-transform IR spectroscopy upon pyridine adsorption, we show that the ν19b pyridinium vibration band only and systematically splits in the presence of agglomerated Keggin units. More precisely, the higher the fraction of agglomerated Keggin units, the more marked the band splitting. So, the latter appears as a fingerprint of agglomerated H3PW12O40. Furthermore, following an easy treatment, the IR spectra allow quantitatively evaluating the fractions of dispersed vs. agglomerated Keggin units within the samples, which is very difficult to achieve through any other technique.

Electrocatalysis of N-doped carbons in the oxygen reduction reaction as a function of pH: N-sites and scaffold effects

Metal-free nitrogenated amorphous carbon electrodes were synthesised via dc plasma magnetron sputtering and post-deposition annealing at different temperatures. The electrocatalytic activity of the electrodes towards the oxygen reduction reaction (ORR) was studied as a function of pH using cyclic voltammetry with a rotating disk electrode. The trends in onset potential were correlated to the carbon nanostructure and chemical composition of the electrodes as determined via Raman spectroscopy and X-ray photoelectron spectroscopy analysis. Results suggest that: 1) the ORR activity in acidic conditions is strongly correlated to the concentration of pyridinic nitrogen sites. 2) At high pH, the presence of graphitic nitrogen sites and a graphitized carbon scaffold are the strongest predictors of high ORR onsets, while pyridinic nitrogen site density does not correlate to ORR activity. An inversion region where pyridine-mediated activity competes with graphitic-N mediated activity is identified in the pH region close to the value of pKa of the pyridinium cation. The onset of the ORR is therefore determined by the activity of different sites as a function of pH and evidence for distinct reduction reaction pathways emerges from these results.

Synthesis, structural and mass spectrometric investigations of pyridinium bis(thiosalicylato)mercurate(II)

This work investigates the synthesis and structural properties of a hydrogen-bonded salt of the [Hg(SC6H4-2-CO2)2]2− ion. The known bis(thiosalicylato)mercury(II) complex [Hg(SC6H4-2-CO2H)2], dissolves in pyridine (py), from which the crystalline pyridinium salt (pyH)2[Hg(SC6H4-2-CO2)2] can be isolated. Single crystal X-ray crystallography reveals two distinct three-molecule aggregates, namely {Hg[SC6H4-2-C(=O)OH]2(NC5H5)2} and {Hg[SC6H4-2-C(=O)O]2(HNC5H5)2}, which differ in the location of the acidic hydrogen atoms, i.e. either compound-bound for the former species or located on the pyridinium cations in the latter. The thiolate ligands are S,O-chelating and the resultant O2S2 four-coordinate geometries are each based on a distorted disphenoidal geometry. The three-molecule aggregates are sustained by hydroxylOH⋯N(pyridine) hydrogen bonds in the case of {Hg[SC6H4-2-C(=O)OH]2(NC5H5)2} whereas the second aggregate features charge-assisted pyridiniumNH⋯O(carboxylate) hydrogen bonds. (pyH)2[Hg(SC6H4-2-CO2)2] was also characterised by negative-ion ESI mass spectrometry, where it showed appreciable stability towards capillary exit voltage-induced fragmentation. In contrast, the S-bonded monodentate thiosalicylate complexes RHg(SC6H4-2-CO2)− (R = Et, Ph or ferrocenyl) undergo facile decarboxylation at relatively low voltages, with the phenyl and ferrocenyl complexes subsequently forming RHgS− as an additional fragment ion at high voltages. Aggregate ions formed with the sodium counter-cations of the type [(RHgSC6H4-2-CO2)nNan−1]− show appreciable stability towards fragmentation.

Crystal structure, physico-chemical characterization and Hirshfeld surface analysis of a new 0D pyridinium dichlorido(dihydrogenphosphato-O,O′)zinc(II)

A new zero-dimensional (0D) chloro-substituted zincophosphate monomer, namely pyridinium dichlorido(dihydrogenphosphato-O,O′)[zinc (II), C5H5NH]ZnCl2(H2PO4), was synthesized via slow evaporation method at room temperature and structurally characterized by single-crystal X-ray diffraction. The structure of this compound is made up of an alternate ZnO2Cl2 and PO2(OH)2 tetrahedra, forming isolated four-membered rings [(ZnCl2PO2(OH)2)2]2− units accompanied by pyridinium cation. The crystal packing is consolidated by O–H···O, O–H···Cl, N–H···Cl and C–H···O hydrogen bonding system and offset π–π interactions, involving anti-parallel neighboring pyridinium rings (inter-centroid distance 3.65 A), which is supported by Columbic attractions between C5H5NH+ cations and (ZnCl2PO2(OH)2)− anions, and Van Der Waals interactions, forming also a supramolecular 3D structure. We discuss quantitatively these interactions using the Hirshfeld surfaces associated with 2D fingerprint plots. This compound was further characterized by solid-state NMR, infrared spectroscopies and DTA/TGA analysis. Solid-state 31P and 13C MAS-NMR spectroscopy results are in full agreement with the X-ray structure.

Toxicity profiling of 24 l-phenylalanine derived ionic liquids based on pyridinium, imidazolium and cholinium cations and varying alkyl chains using rapid screening Vibrio fischeri bioassay

A library of 24 pyridinium-, imidazolium-, and cholinium-based ionic liquids (ILs) with varying alkyl chain from C2 to C16 was toxicologically profiled using naturally luminescent marine bacteria Vibrio fischeri. The toxicity (30-min EC50) of studied ILs to Vibrio fischeri ranged from 7.82 µM (4.2 mg/L) (PyC12Phe) to 3096 µM (1227 mg/L) (ImidC2Phe), i.e. from “toxic” (EC50 1–10 mg/L) to “not harmful” (EC50 > 100 mg/L). Inhibition of the bacterial luminescence upon 30-min exposure to ILs correlated well with bacterial viability (exposure for 4 h). The toxicity of studied ILs was largely driven by the length of the alkyl chain (hydrophobicity) and not the type of cationic part of the IL: starting from C10 all the ILs irrespective of the cationic part proved “toxic”. The toxicity of the studied ILs was increasing in parallel to their hydrophobicity up to log Kow = 1 (C8–C10) and then levelling up, being consistent with the previously obtained analogous data sets. The “cut-off” effect reported in this study for longer chain length members of the ILs series leads to the “limit” toxicity level for this type of ILs to be ca. 8 mM. Two open-access online tools (www.molinspiration.com and www.vcclab.org) have been applied for the calculation of the Kow values for the 24 ILs reported in this study and 21 ILs reported in the literature. This lead to plotting two nonlinear monotonic correlations between the values of experimental log (1/EC50) and calculated log Kow. The limitation of the online tools and an effect of the ILs structure on the “cut-off” effect have been discussed. The challenge of developing low microbial toxicity surface active ILs remains a significant task to overcome. Our results shed light on the new approaches for designing environmentally benign ILs and functional surfactants. As the hydrophobicity of the ILs significantly correlated with the toxicity, the Vibrio fischeri assay could be considered a powerful tool in providing toxicity data for building and evaluating the QSAR toxicity models for ILs.

Crystal structure of the co-crystal salt 2-amino-6-bromo-pyridinium 2,3,5,6-tetra-fluoro-benzoate.

The asymmetric unit of the co-crystal salt 2-amino-6-bromo-pyridinium 2,3,5,6-tetra-fluoro-benzoate, C5H6BrN2 +·C7HF4O2 -, contains one pyridinium cation and one benzoate anion. In the crystal, the amino-pyridinium cationic unit forms two hydrogen bonds to the benzoate oxygen atoms in an R 2 2(8) motif. Two pyridinium benzoate units are hydrogen bonded through self-complementary hydrogen bonds between the second amine hydrogen and a carboxyl-ate O with a second R 2 2(8) motif to form a discrete hydrogen-bonded complex containing two 2-amino-6-bromo-pyridinium moieties and two 2,3,5,6-tetra-fluoro-benzoate moieties. The 2-amino-6-bromo-pyridinium moieties π-stack in a head-to-tail mode with a centroid-centroid separation of 3.7227 (12) Å and adjacent tetra-fluoro-benzoates also π-stack in a head-to-tail mode with a centroid-centroid separation of 3.6537 (13) Å.

Design and construction of novel assemblies for monosaccharides and glycosides detection

A series of new cationic pyridine analogues modified boronic acid were synthesized and established fluorescence probes with dye 8-hydroxypyrene- 1,3,6-trisulfonic acid trisodium salt (HPTS). This kind cationic pyridine analogues as quenchers/connectors in two-components probes displayed higher sensitivity and selectivity for monosaccharides than that of boronic acid functionalized benzyl viologens (BBVs) as quenchers. To investigate the effects of the number of positive charges and boronic acid of these quenchers/connectors, a series of new assemblies comprised of HPTS dye as fluorophor and pyridine analogues as quenchers/connectors were established and employed to detect monosaccharides, respectively. These results displayed that TCTB with three positive charges and three boronic acid groups could interact with anionic dye HPTS forming the most sensitive two-component sensor for monosaccharides. Furthermore, TCTB/HPTS assembly may be also employed to detect saccharides in the blood of diabetes patient. Notably, the assembly could distinguish the three main glycosides of the herb forsythia and had a high selectivity for forsythoside A. The work not only provided high effective two-component probes but also exploited a new mode for detecting and distinguishing main ingredients of Chinese herbal medicine.

Cation-π interactions secure aggregation induced emission of planar organic luminophores.

The use of non-covalent intermolecular π+-π interactions between quaternary pyridinium or imidazolium cations and aromatic π systems is an efficient approach to achieve AIE in planar purely organic luminophores.

Flammability and combustion behavior of cotton fabrics treated by the sol gel method using ionic liquids combined with different anions

An ionic liquid (IL)-assisted cotton fabric treatment was developed that uses the sol–gel method, methylimidazolium and pyridinium cations combined with Cl−, PF6−, (CF3SO2)2N−, BF4− and CH3CO2− anions. Scanning electron microscopy, elemental analysis and Fourier transform infrared spectroscopy were first performed to characterize the morphology and the chemical composition of the treated and untreated cotton fabrics. Furthermore, the effect of IL-based treatment on the tensile strength of cotton fabrics was evaluated using a uniaxial tensile test. The thermal behavior of cotton fabrics was investigated by thermogravimetric analysis, microscale combustion calorimetry, limiting oxygen index (LOI) and vertical burning test. It was found that the as produced IL-treated cotton fabrics exhibited a good thermal stability and showed good flame retardant properties. The best result was found for fabrics treated by IL combined with PF6− anion, in which the total heat release value was reduced from 11.47 kJ/g for untreated fabrics to 6.32 kJ/g for treated fabrics. The result from LOI test indicated that the treated cotton fabrics exhibited a better LOI value of 25% compared to the untreated fabrics (LOI = 20%), indicating that IL-based treatment has contributed to the protection of cotton fabrics from degradation. Herein, we demonstrate that IL-assisted sol–gel method could be used as an effective approach to develop cotton fabrics with improved characteristics for textile application.