Series Of Salts Research Articles

Physicochemical and thermodynamic properties of the {1-alkyl-1-methylpiperidinium bromide [C1Cn=2,4PIP][Br], or 1-butylpyridinium bromide, [C4Py][Br], or tri(ethyl)butylammonium bromide [N2,2,2,4] [Br] + water} binary systems

This work is a continuation of our comprehensive study of ionic liquids, ILs (including organic salts with melting temperature above 100 °C) and their aqueous solutions as a novel alternative working pair for the absorption heat pump. A series of organic salts: 1-ethyl-1-methyl-piperidinium bromide, [C1C2PIP][Br], 1-butyl-1-methyl-piperidinium bromide, [C1C4PIP][Br], 1-butylpyridinium bromide, [C4Py][Br] and tri(ethyl)butylammonium bromide, [N2,2,2,4][Br] have been synthesized. The structures of compounds have been confirmed using NMR spectra. The basic thermal characterization of pure organic salts, including temperature and enthalpy of phase transition (Ttr, ΔtrH), temperature and enthalpy of melting (Tfus, ΔfusH) have been measured using a differential scanning microcalorimetry technique (DSC). The physico-chemical properties that are: density (ρ) and dynamic viscosity (η) of the tested binary systems have been determined at wide temperature and composition range. From experimental densities data, the apparent molar volumes (Vϕ,1) were calculated. In order to obtain limiting apparent molar volumes (Vϕ,10), the concentration dependence of apparent molar volumes was correlated with Redlich–Mayer type equation. Additionally, the limiting molar expansibilities (Eϕ0) and isobaric thermal expansion coefficients (αP) have been calculated. Temperature dependence of the dynamic viscosity has been correlated using VFT equation. The solid−liquid phase equilibria (SLE) have been determined using a dynamic method and correlated using NRTL equation. The influence of the alkyl chain length in the piperidinium cation substituent, as well as the cation structure, on investigated properties are presented and discussed.

Imidazolinium chloride salts bearing wingtip groups: Synthesis, molecular docking and metabolic enzymes inhibition

A series of symmetrical imidazolinium chloride salts bearing secondary N-alkyl substituents were synthesized in good yield by the reaction of N,N′-dialkylethane-1,2-diamines and HC(OEt)3 in the presence of NH4Cl. These salts were characterized by spectroscopic methods. All compounds were tested as enzyme inhibitory agents. These novel symmetrical imidazolinium chloride salts derivatives (3a-h) effectively inhibited the cytosolic hCA I and hCA II, BChE, α-glycosidase and AChE with Ki values in the range of 18.41–121.73 nM for hCA I, 12.50–63.12 nM for hCA II, 3.72–34.58 nM for AChE, 5.50–32.36 nM for BChE, and 94.72–364.51 nM for α-glycosidase, respectively. CA isoenzymes play a crucial roles including acid-base balance homeostasis by excreting and secreting protons (H+) due to the CO2 hydration, HCO3− reabsorption mechanisms, and renal NH4+ output. Also, the molecular modeling is an implementation for estimation of the binding proximity of symmetrical imidazolinium chloride salts bearing secondary wingtip groups and their inhibition mechanisms and kinetics in atomic levels at the catalytic domains.

Catalytic polymerization of CO2 to polyureas over K3PO4 catalyst

A series of potassium alkali salts (K3PO4, K2HPO4, KH2PO4, K2CO3, KHCO3) were applied in CO2 conversion to polyureas. It was observed that the catalytic activity was related to the alkalinity of salts and solvents. K3PO4 was found to be a highly active catalyst for the polymerization of CO2, and various polyureas were achieved from inferior to superior yields. Characterization of spent catalyst by IR and XRD demonstrated that the K3PO4 was completely transformed into less active K2HPO4, KH2PO4 and KHCO3 via reaction with CO2 and water during the polymerization process. The products were examined by IR, 13C NMR, TGA and DSC, indicating that the product obtained from CO2 possesses the ureas structure and good thermal stability.

Systematic evaluation of inorganic salts as a heat sink for the magnesiothermic reduction of silica

In this study, the effectivity of a series of inorganic salts, sodium chloride, calcium chloride, magnesium chloride, potassium chloride, and sodium bromide as heat sinks during magnesiothermic reduction of silica to porous silicon was investigated. The salts were chosen based on cost, thermal stability, ability to remain chemically inert during the reduction process, and ease of removal after the reaction. The structural integrity of the spherical porous silicon nanoparticles was observed using scanning electron microscopy, the surface area was determined via nitrogen adsorption experiments, and the crystallite size was determined using powder X-ray diffraction analysis; together, these were used to determine the efficacy of each salt. The ability of a salt to act as an effective heat sink was found to be highly correlated and principally dependent on the heat capacity of the salt. Calcium chloride was found to be the most effective heat sink overall among the five heat sinks investigated here.

A novel β-nucleating agent for isotactic polypropylene

A series of metal salts of 7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid were synthesized, and their nucleation efficiency in isotactic polypropylene (iPP) was investigated. The results showed that potassium 7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboxylate (OBCHE19) is an effective β-nucleating agent. Then, the effect of OBCHE19 concentration on the relative content of β-crystals (Kβ) and mechanical properties of iPP was investigated. The results indicated that the maximum Kβ reached 0.82 and impact strength increased by 125% compared to that of pure iPP when the content of OBCHE19 is 0.1 mass%. Furthermore, the non-isothermal crystallization kinetics and crystallization activation energy were investigated by the Caze method and Kissinger method, respectively.

Ionic liquid-crystalline polymer-based quaternary phosphonium salt

ABSTRACTA series of quaternary phosphonium salts based on ionic liquid-crystalline polymers which were synthesised by triphenylphosphine and brominated polysiloxanes containing cholesteryl mesogens. The chemical structures, liquid crystalline properties and antimicrobial performance of [ChP]Brs were investigated by a series of test methods. [ChP]Brs showed smectic A mesophase with a wide temperature range of liquid crystalline phase in the heating and cooling cycles. The glass transition temperature and clearing point temperature decreased with the increase of triphenylphosphine content. While the increase of phosphorus content lead to the increase of antibacterial properties of polymers. The liquid crystal polymer provides full spatial support for complete contact between phosphorus ions and bacteria, So that the quaternary phosphonium salt can be fully sterilised.

Molecular Deformation, Charge Flow, and Spongelike Behavior in Anion-π {[M(CN)4 ]2- ;[HAT(CN)6 ]}∞ (M=Ni, Pd, Pt) Supramolecular Stacks.

The synthesis, crystal structures, spectroscopic characterization, and comprehensive quantum-chemical calculations for a novel series of anion-π hybrid salts (XPh4 )2 [M(CN)4 ][HAT(CN)6 ]⋅3 MeCN (X=P, M=NiII (1), PdII (3), PtII (5); X=As, M=NiII (2), PdII (4), PtII (6); HAT(CN)6 =1,4,5,8,9,11-hexaazatriphenylenehexacarbonitrile) are presented. The systems comprise 1D {[M(CN)4 ]2- ;[HAT(CN)6 ]}∞ stacks, in which the electron-rich metal complexes adjust their orientation to match the electron-deficient areas of HAT(CN)6 . Electronic charge-transfer interactions along the stacks result in polarization of electron density within HAT(CN)6 and in perturbations along the {[M(CN)4 ]2- ;[HAT(CN)6 ]}∞ contacts. Electronic structure analysis suggests, for example, a relocation of 0.1-0.2 e per molecule from [M(CN)4 ]2- to HAT(CN)6 and anion-π interaction energies of around -65 kcal mol-1 . A reversible structural single-crystal-to-single-crystal transformation, through desolvation/resolvation processes in the solid state, is also reported and a scheme for the formation of anion-π [M(CN)4 ]2- /HAT(CN)6 adducts in MeCN is proposed.

Thermodynamic and micellization behavior of long chain 1-octyl-2,3-dimethylimidazolium bromide [odmim][Br] in aqueous solution in the absence and in presence of a series of alkali salts

The alkali salts (0.1 mol·kg−1 LiCl, LiBr, NaCl, NaBr, and KCl) markedly affect the aggregate formation of trisubstituted imidazolium based ionic liquid (IL), 1-octyl-2,3-dimethylimidazolium bromide [odmim][Br] in aqueous media. Various techniques such as surface tension at 298.15 K and conductivity from 288.15 to 308.15 K has been studied. The surface parameters such as critical aggregation concentration (CAC), adsorption efficiency, interface surface pressure, surface tension at CAC, minimum surface cover by a single molecule, maximum area excess concentration were calculated from surface tension measurements with and without salts. The CAC value of trisubstituted IL has been found lower than the CAC value of disubstituted ionic liquid (IL), 1-octyl-3-methylimidazolium bromide [omim][Br]. It suggests that the H-bonding in [omim][Br] is dominant that results in formation of larger aggregates in comparison to smaller aggregates formed by [odmim][Br]. The presence of alkali salts helped in the formation of still larger aggregates of [odmim][Br] because of electrostatic attractive interactions present between the cationic and anionic counter parts. Formation of aggregates at lower concentration predicts that [odmim][Br] acts as a better cationic surfactant.

Benzoylguanidines as Anion-Responsive Systems.

A series of benzoylguanidinium salts was prepared and the changes in UV/Vis spectra, triggered by the presence of anions, were investigated. All compounds undergo deprotonation with basic anions like dihydrogenphosphate and acetate in acetonitrile. The most pronounced spectral changes were obtained by deprotonation of N1 -benzoyl-N3 -(p-nitrophenyl) guanidinium chloride which shows the naked-eye visible color change from colorless to yellow. Measured pKa (BH+ ) in acetonitrile ranges from 12-16, which is comparable to the pyridinium cations. The proton transfer equilibria were also tested in acetonitrile/water mixture where all but the most acidic derivatives showed pKa (BH+ ) of 4-6 units which corresponds to apparent association constants of 104 -106 dm3 mol-1 . UV/Vis spectra of neutral and protonated forms were modelled by the TD-DFT approach using CAM-B3LYP and PBE0 functionals and compared to CC2 results. In the case of CAM-B3LYP, a parameter ω, defining amount of long-range exchange correction, was varied to achieve the best agreement with the experimental spectra. The optimized ω parameters are 0.10 a0 -1 for neutral benzoylguanidines and 0.20 a0 -1 for neutral nitrobenzoyl and protonated systems. The larger ω parameter in the latter is ascribed to more pronounced charge transfer character of the HOMO-LUMO transition - the one responsible for the lowest energy absorption band.

Crystal structure investigation for series of salts of 2Me-5NA with different acids

Crystal structure investigation for series of salts of 2Me-5NA with different acids

Porous Cubic Cesium Salts of Silicododecatungstate(molybdate)/Borododecatungstate Blends: Synthesis and Molecular Adsorption Properties.

In this work, the synthesis and molecular adsorption properties of cubic cesium salts of Keggin-type silicododecametalates (SiM; M = W or Mo) and borododecatungstate (BW) blends were reported. Pentavalent BW, which is normally packed in a monoclinic fashion, could be packed into the desired cubic fashion by being blended with tetravalent SiW or SiMo. By simply mixing aqueous solutions containing SiM and BW in different SiM:BW molar ratios [SiM:BW = N:(100 - N), where N is the percentage of SiM in the synthetic solution and equals 100, 80, 50, 30, 20, 10, or 5] with a cesium nitrate solution, we obtained a series of cubic cesium salts (CsSiMBW- N) with POM vacancy-like pores (i.e., kinetically formed interparticle pores). Notably, the yields, compositions, and BET surface areas of the obtained CsSiMBW- N were dependent on only the N values and independent of SiW or SiMo. In CsSiMBW- N, SiM and BW were well blended at the molecular (nanometer) level. The nitrogen, water, and ethanol adsorption properties of CsSiWBW- N systematically changed according to the SiW:BW molar ratios. In the case of SiW-rich salts, nitrogen, water, and ethanol were adsorbed in the pores; the amounts of nitrogen, water, and ethanol adsorbed were nearly identical for CsSiWBW-100. When the SiW:BW molar ratio was decreased, the salts selectively incorporated water and ethanol within the pores. In the case of CsSiWBW-5, barely any nitrogen was adsorbed. The plausible mechanisms for particle growth and interparticle POM vacancy-like pore formation are also discussed.

Nucleation effect of adipic acid metal salts in isotactic polypropylene

A series of adipic acid metal salts as nucleating agents for isotactic polypropylene (iPP) were synthesized from adipic acid (Adi) and corresponding metal hydroxides or chlorides by neutralization or double decomposition reaction. The effect of different adipate on the crystallization and melting behavior of iPP were investigated by differential scanning calorimetry (DSC). The results indicated that after adding different metal salts of adipic acids, the crystallization peak temperature of nucleated iPP was increased by different degree. Adi, barium adipate (Adi-Ba), and zinc adipate (Adi-Zn) had higher nucleation efficiency. Notably, Adi-Zn and Adi-Ba were highly effective β-crystal nucleating agents; the others were α-crystal nucleating agents. In addition, the relative content of β-crystals in nucleated iPP was higher than 0.9 with the addition of Adi-Ba or Adi-Zn, especially when Adi-Zn was added at 0.05 mass% reached 0.9422, indicating that Adi-Ba and Adi-Zn are highly active and selective β-nucleating agents for iPP.

Fine Tuning of Emission Behavior, Self-Assembly, Anion Sensing, and Mitochondria Targeting of Pyridinium-Functionalized Tetraphenylethene by Alkyl Chain Engineering.

Compared to the many studies that focus on the development of novel molecular frameworks pertaining to functionalized fluorescent materials, there is lesser emphasis on side chains even though they have a significant impact on the properties and applications of fluorescent materials. In this study, a series of pyridinium-functionalized tetraphenylethene salts (TPEPy-1 to TPEPy-4) possessing different alkyl chains are synthesized, and the influence of chain length on their optical performance and applications is thoroughly investigated. By changing the alkyl chain, the fluorogens exhibit opposite emission behavior in aqueous media because of their distinct hydrophobic nature, and their solid-state emission can be fine-tuned from green to red owing to their distinct molecular configuration. In addition, by increasing the chain length, the microstructure of the self-assembled fluorogens converts from microplates to microrods with various emission colors. Moreover, TPEPy-1 exhibits dual-mode fluorescence "turn-on" response toward NO3- and ClO4- in aqueous media because the anions induce the self-assembly of fluorogens. Furthermore, the fluorogens display cellular uptake selectivity while the proper alkyl chain impels the fluorogens to penetrate the cell membrane and accumulate in the mitochondria with high specificity.

Synthesis, Antimicrobial Effect and Surface Properties of Hydroxymethylsubstituted Pyridinium Salts

Background: The cationic surfactants are a huge group of compounds with thousands of applications. Quaternary Ammonium Salts (QAS) make up the majority of this group. Their countless applications in chemistry, the food industry and textile industry are indubitable. The antibacterial and antifungal effect of the various novel QAS is usually referred to in comparison with commercially used benzalkonium and pyridinium salts, since such compounds have found widespread use as common disinfectants e.g. in hospitals as prevention against nosocomial infections. Methods: Three series of N-alkylpyridinium salts with a hydroxymethyl group in positions 2, 3 and 4 were synthesized as novel potential antimicrobial agents. The nucleophilic substitution-type reaction has been used. The novel compounds have been tested as a disinfection agents against bacteria and fungi. The microdilution broth method was utilized for antimicrobial evaluation. Conductivity measurement method has been used for the determination of Critical Micelle Concentration (CMC). Standard MTT test was used for cytotoxic evaluation. Results: We have prepared 15 new compounds based on hydroxymethylpyridine in different positions (2, 3, 4) and the different length of lipophilic alkyl chain on the quaternary nitrogen (C10-18). The compounds were characterized with analytical data (NMR, HRMS) and tested for in vitro antimicrobial activity. The highest, and submicromolar antimicrobial activity was achieved for the 3- hydroxymethylpyridinium salts substituted with longer alkyl chains (C14, C16 and C18). Nhexadecyl- 3-hydroxymethylpyridinium bromide (10b) showed even better performance than standard benzalkonium salts. Conductometric analysis confirmed the trend of decreasing CMC with elongation of the alkyl side chain. Generally, the location of the hydroxymethyl function on the pyridinium scaffold induced only negligible changes in antimicrobial efficacy. Finally, potential use of the N-alkylhydroxymethylpyridinium salts in practice was supported by MMT tests which proved relatively low cytotoxicity of the compounds. Conclusion: We have designed, synthesized and characterized three series of cationic surfactants based on 2-, 3- and 4-hydroxymethylpyridine. The cationic surfactants differ in the length of alkyl side-chain (C10, C12, C14, C16, C18). The antimicrobial effect was evaluated against four groups of microorganisms (gram- positive and gram-negative bacteria, yeasts, and filamentous fungi). The Critical Micelle Concentrations (CMC) were measured by conductivity method, and finally cytotoxicity tests were performed. Keywords: Hydroxymethylpyridinium salts, antimicrobial activity, synthesis, quaternary ammonium salts, critical micelle concentration, conductivity, cytotoxicity.

Visible-Light-Sensitive Sulfonium Photoacid Generators Bearing a Ferrocenyl Chromophore

A series of sulfonium salts bearing a ferrocenyl chromophore, [FcMeArS][X] (Ar = Ph, 4-CH3C6H4; X = BF4, PF6, BArF4), has been synthesized, which can generate an acid under 436 nm irradiation. The present study provides a rare example of ferrocene derivatives having a photoacid-generating function.

Robust Organocatalysts for the Cleavage of Vegetable Oil Derivatives to Aldehydes through Retrobenzoin Condensation.

A series of thiazolium salts was prepared and tested for the cleavage of the α-hydroxyketone derived from methyl oleate. The robustness of these precatalysts was determined by dynamic thermogravimetric analyses (TGA). It has been shown that the stability of these species is mainly governed by the nature of the counter-anion and some of them were found to be stable until 350-400 °C. The α-hydroxyketone derived from methyl oleate was cleaved under reactive distillation conditions using optimized, thermally robust N-butylthiazolium triflate to give the cleavage product, namely, nonanal and methyl azelaaldehydate, with 85 and 70 % yields. A range of α-hydroxyketones derived from several fatty acids was cleaved to give the corresponding bio-based aldehydes with up to 98 % isolated yields. Finally, this protocol was successfully applied to a high-oleic sunflower oil derivative.

Role of S…O non-bonded interaction in controlling supramolecular assemblies in a new series of 2-aminobenzothiazole based organic salts/ co-crystals

A new series of 2-aminobenzothiazole based organic salts were synthesized with mono- / di-carboxylic acid and characterized with various physico-chemical methods. One of the synthesized salt 2-aminobenzothiazolium-hydrogen fumarate (BTzA4) was found to be capable of gelling water with minimum gelator concentration (MGC) around 1.25 wt% (w/v). The single crystal structures of gelator (BTzA4) and non-gelators were analyzed for the presence of various supramolecular synthons especially the rarely occurring non-bonded S…O interactions and their role in controlling the overall hydrogen bonded network in these series of salts/ cocrystals. Charge assisted hydrogen bonded network was found to be governing the weak non-bonded S…O supramolecular synthons in the present study.

Synthesis, characterisation and cytotoxic properties of N -heterocyclic carbene silver(I) complexes

Abstract A benzimidazolium salt bearing hydroxyethyl group, 1a and a new series of zwitterionic sulphonated benzimidazolium salts, 1b–e were reacted with Ag2O to produce Ag(I)-N-heterocyclic carbene (NHC) complexes, 2a–e respectively. Synthesised silver(I)-N-heterocyclic carbene complexes were fully characterised by 1H and 13C NMR, elemental analysis and HRMS spectroscopic methods. Anti-cancer potential of both NHC salts and complexes were tested and the IC50 values of these NHC salts and complexes were determined by a proliferation BrdU enzyme-linked immunosorbent assay (ELISA) against HeLa (Human cervix carcinoma), HT29 (human adenocarcinoma) and L929 (mouse fibroblast) cell lines. The IC50 values are in the range of 11 ± 1–126 ± 3 μM show that all new Ag(I)-NHC complexes especially complex 2b demonstrated remarkable cytotoxic activity against HeLa, HT29 and L929 while 1a–e NHC salts are found to be inactive against HeLa, HT29 and L929. Also, the high IC50 value of complex 2b against L929 cells can be interpreted high selectivity against healthy cells. This complex has been highlighted as new types of metalodrug.

The Impact of Salts Formed by the Neutralisation of (Ligno)Cellulose Hydrolysates on the Hydrogenation of Sugars

AbstractDilute acid hydrolysis of lignocellulose often requires a neutralisation step to utilise the hydrolysate's sugars. In this context, very little is known regarding the impact of low levels of acids or their corresponding salts produced by neutralisation on the catalyst performance in the hydrogenation of sugars. In this work, the influence of a series of ammonium and alkali metal salts (that is, NH4NO3, NaNO3, (NH4)2SO4, Na2SO4 and K2SO4) on the hydrogenation of glucose and xylose is addressed. This study also encompasses “real‐world” hydrolysates obtained by the mechanocatalytic depolymerisation of α‐cellulose and beechwood. The impact of low levels of acids and their salts upon the hydrogenation of sugars to sugar alcohols (alditols) was examined, in the presence of a commercial Ru/C catalyst (Ru/C, 0.7 wt % Ru) at 110 °C using batch and trickle‐bed reactors. The results show that the presence of salts leads to a considerable decrease in the alditols yields. Notably, salt anions exert an effect stronger than that of cations in the catalyst deactivation. Surprisingly, nitrates had a more significant effect on the decrease in the alditols yield than sulfates, and chlorides had the lowest impact. In this study, we also present the effect of sugars’ degradation products (e.g. 5‐(hydroxymethyl)furfural and furfural) upon hydrogenation of lignocellulose hydrolysates. The activated carbon pre‐treatments of the hydrolysates showed a positive effect on the catalyst activity, adsorbing hydrolysis by‐products. Overall, this study has significant implications for the practical aspects of hydrogenation of lignocellulose hydrolysates, which are often neglected in the current literature.

Dicyanamide Salts that Adopt Smectic, Columnar, or Bicontinuous Cubic Liquid-Crystalline Mesophases.

Although dicyanamide (i.e., [N(CN)2 ]- ) has been commonly used to obtain low-viscosity, halogen-free, room-temperature ionic liquids, liquid-crystalline salts containing such anions have remained virtually unexplored. Here we report a series of amphiphilic dicyanamide salts that, depending on their structures and compositions, adopt smectic, columnar, or bicontinuous cubic thermotropic liquid-crystalline mesophases, even at room temperature in some cases. Their thermal properties were explored by polarized light optical microscopy, differential scanning calorimetry, thermogravimetric analysis (including evolved gas analysis), and variable-temperature synchrotron X-ray diffraction. Comparison of the thermal phase characteristics of these new liquid-crystalline salts featuring "V-shaped" [N(CN)2 ]- anions with those of structural analogues containing [SCN]- , [BF4 ]- , [PF6 ]- , or [CF3 SO3 ]- anions indicated that not only the size of the counterion but also its shape should be considered in the development of mesomorphic salts. Collectively, these discoveries may be expected to facilitate the design of thermotropic ionic liquid crystals that form inverted-type bicontinuous cubic and other sophisticated liquid-crystalline phases.