Chemical characteristics and molecular interactions causing liquid clathrate formation

International audienc

Procainium Acetate Versus Procainium Acetate Dihydrate: Irreversible Crystallization of a Room-Temperature Active Pharmaceutical-Ingredient Ionic Liquid upon Hydration

Anhydrous procainium acetate is a room temperature ionic liquid (<i>T</i>_g = −25 °C); however, in the presence of water, this salt forms a crystalline dihydrate (<i>T</i>_m = 52 °C) that cannot be dehydrated without decomposition. Unintended crystallization of any active pharmaceutical ingredient can dramatically alter its solubility and bioavailability, making it essential that ionic liquid APIs be carefully studied for their crystallization behavior

Acyclovir as an Ionic Liquid Cation or Anion Can Improve Aqueous Solubility

Six ionic liquid (IL)-forming ions (choline, tetrabutylphosphonium, tetrabutylammonium, and trimethylhexadecylammonium cations, and chloride and docusate anions) were paired with acyclovir as the counterion to form four low melting solid salts and two waxes; five of these compounds could be classified as ILs. All of the newly synthesized acyclovir ILs exhibited increased aqueous solubilities by at least 2 orders of magnitude when compared to that of neutral acyclovir. For three of the prepared compounds, the solubilities in simulated body fluids (phosphate-buffered saline, simulated gastric, and simulated intestinal fluids) were also greatly enhanced when compared to that of neutral acyclovir. Acyclovir in its anionic form was more water- or buffer-soluble than acyclovir in its cationic form, though this might be the effect of the particular ions, indicating that the solubilities can be finely tuned by proper choice of the cationic or anionic form of acyclovir and the counterion paired with it

Evaluating Ionic Liquids as Hypergolic Fuels: Exploring Reactivity from Molecular Structure

International audienceA total of 38 ionic liquids (19 of which are new) comprised of 13 cations, 1-propargyl-3-methyl-imidazolium, 1-allyl-3-methyl-imidazolium, 1,3-dimethyl-imidazolium, 1-ethyl-3-methyl-imidazolium, 1-butyl-3-methyl-imidazolium, 1-methoxyethyl-3-methyl-imidazolium, 1-methyl-4-butyl-1,2,4-triazolium, 1-methyl-4-allyl-1,2,4-triazolium, 1-methyl-4-amino-1,2,4-triazolium, N-butyl-N-methyl-pyrrolidinium, N-allyl-N-methyl-pyrrolidinium, N-allyl-pyridinium, and N-butyl-3-methyl-pyridinium, paired with three anions, dicyanamide, azide, and nitrocyanamide, have been prepared, characterized, and evaluated as potential hypergolic fuels by determining key physical, thermal, and ignition properties. The reactivity of these ionic liquids (32 liquids and 6 solids which melt below 100 degrees C) was strongly correlated to increased electron density in the cation, while small changes in physical properties had little effect beyond a certain threshold, suggesting that subtle changes in chemical reactivity can greatly influence the hypergolic ignition pathway

Molecular interactions in aqueous biphasic systems composed of polyethylene glycol and crystalline vs. liquid cholinium-based salts

The relative ability of cholinium-([Ch](+))-based salts, including ionic liquids (ILs), to form biocompatible aqueous biphasic systems (ABS) with polyethylene glycols (PEGs) was deeply scrutinized in this work. Aqueous solutions of low molecular weight PEG polymers (400, 600, and 1000 g mol(-1)) and [Ch](+) salts of chloride, acetate, bicarbonate, glycolate, lactate, dihydrogenphosphate, dihydrogencitrate, and bitartrate can undergo liquid-liquid demixing at certain concentrations of the phase-forming components and at several temperatures. Cholinium butanoate and propanoate were also studied; however, these long alkyl side chain ILs are not able to promote an immiscibility region with PEG aqueous solutions. The ternary liquid-liquid phase diagrams, binary water activities, PEG-salt and salt-H2O solubility data, and binary and ternary excess enthalpies estimated by COSMO-RS (COnductor-like Screening MOdel for Realistic Solvation) were used to obtain new insights into the molecular-level mechanisms responsible for phase separation. Instead of the expected and commonly reported salting-out phenomenon induced by the [Ch](+) salts over the polymer, the formation of PEG-[Ch](+) salt ABS was revealed to be an end result of a more intricate molecular scenario. The multifaceted approach employed here reveals that the ability to promote an ABS is quite different for the higher melting salts vs. the lower melting or liquid ILs. In the latter systems, the ABS formation seems to be controlled by the interplay of the relative strengths of the ion-ion, ion-water, ion-PEG, and water-PEG interactions, with a significant contribution from specific hydrogen-bonding between the IL anion and the PEG hydroxyl groups

Glyphosate-Based Herbicidal Ionic Liquids with Increased Efficacy

Eight new glyphosate-based herbicidal ionic liquids (HILs), containing both mono- and dianions of glyphosate (benzalkonium glyphosate, bis­(2-hydroxyethyl)­cocomethylammonium glyphosate, oleylmethylbis­(2-hydroxyethyl)­ammonium glyphosate, didecyldimethylammonium glyphosate, di­(hydrogenated tallow)­dimethylammonium glyphosate, 4-decyl-4-ethylmorpholinium glyphosate, di­(benzalkonium) glyphosate, and di­(bis­(2-hydroxyethyl)­cocomethylammonium) glyphosate) were prepared via acid–base reaction between the corresponding ammonium hydroxides (some premade) and glyphosate free acid. The transformation of glyphosate free acid into ionic liquids led to an elimination of melting points in all but one compound and significant change in solubilities. All HILs exhibited higher thermal stability than glyphosate free acid. Greenhouse testing indicated that while at a higher application rate of 360 g/ha the efficacy of all the HILs was comparable to the commercial herbicide control, at a lower application rate of 180 g/ha, the efficacy of all HILs was as much as two and a half to three times higher when compared to the commercial formulation, and the dianionic glyphosates were the most effective. In field trials, all but one of the tested HILs demonstrated excellent efficacy. Laboratory regrowth tests established that the ionic liquids of glyphosate are efficiently translocated to rhizomes preventing the regrowth of plants

Two Herbicides in a Single Compound: Double Salt Herbicidal Ionic Liquids Exemplified with Glyphosate, Dicamba, and MCPA

Herbicidal ionic liquids (HILs) have been demonstrated to have potential as highly effective herbicides that may also have different modes of action that their neutral precursors. Here, <i>double salt</i> herbicidal ionic liquids (DSHILs) containing at least two herbicidal anions selected from glyphosate, dicamba, or 4-chloro-2-methylphenoxyacetate (MCPA) paired with ammonium or phosphonium cations are reported along with their post-emergence herbicidal activity against several plant species, from both greenhouse and field study-based bioassays. The novel DSHILs were shown to integrate the advantages of two different herbicides into a single HIL, enhance herbicidal efficacy, and reduce the risk of weed resistance due to the various modes of action of the applied treatment. The formation of the DSHILs dramatically reduced melting points and modified the compound solubilities compared to the parent herbicides. Statistical analyses for the greenhouse efficacy tests demonstrated that DSHILs had significant positive differences against winter wheat (Triticum aestivum L.) and white mustard (Sinapis alba L.) as compared to commercial formulations. Biodegradability studies were also performed on selected DSHILs, and the compounds were found to be not readily biodegradable

Evaluating Ionic Liquids as Hypergolic Fuels: Exploring Reactivity from Molecular Structure

A total of 38 ionic liquids (19 of which are new) comprised of 13 cations, 1-propargyl-3-methyl-imidazolium, 1-allyl-3-methyl-imidazolium, 1,3-dimethyl-imidazolium, 1-ethyl-3-methyl-imidazolium, 1-butyl-3-methyl-imidazolium, 1-meth-oxyethyl-3-methyl-imidazolium, 1-methyl-4-butyl-1,2,4-triazolium, 1-methyl-4-allyl-1,2,4-triazolium, 1-methyl-4-amino-1,2,4-tri-azolium, <i>N</i>-butyl-<i>N</i>-methyl-pyrrolidinium, <i>N</i>-allyl-<i>N</i>-methyl-pyrrolidinium, <i>N</i>-allyl-pyridinium, and <i>N</i>-butyl-3-methyl-pyridinium, paired with three anions, dicyanamide, azide, and nitrocyanamide, have been prepared, characterized, and evaluated as potential hypergolic fuels by determining key physical, thermal, and ignition properties. The reactivity of these ionic liquids (32 liquids and 6 solids which melt below 100 °C) was strongly correlated to increased electron density in the cation, while small changes in physical properties had little effect beyond a certain threshold, suggesting that subtle changes in chemical reactivity can greatly influence the hypergolic ignition pathway

Evaluating Ionic Liquids as Hypergolic Fuels: Exploring Reactivity from Molecular Structure

A total of 38 ionic liquids (19 of which are new) comprised of 13 cations, 1-propargyl-3-methyl-imidazolium, 1-allyl-3-methyl-imidazolium, 1,3-dimethyl-imidazolium, 1-ethyl-3-methyl-imidazolium, 1-butyl-3-methyl-imidazolium, 1-meth-oxyethyl-3-methyl-imidazolium, 1-methyl-4-butyl-1,2,4-triazolium, 1-methyl-4-allyl-1,2,4-triazolium, 1-methyl-4-amino-1,2,4-tri-azolium, <i>N</i>-butyl-<i>N</i>-methyl-pyrrolidinium, <i>N</i>-allyl-<i>N</i>-methyl-pyrrolidinium, <i>N</i>-allyl-pyridinium, and <i>N</i>-butyl-3-methyl-pyridinium, paired with three anions, dicyanamide, azide, and nitrocyanamide, have been prepared, characterized, and evaluated as potential hypergolic fuels by determining key physical, thermal, and ignition properties. The reactivity of these ionic liquids (32 liquids and 6 solids which melt below 100 °C) was strongly correlated to increased electron density in the cation, while small changes in physical properties had little effect beyond a certain threshold, suggesting that subtle changes in chemical reactivity can greatly influence the hypergolic ignition pathway

Evaluating Ionic Liquids as Hypergolic Fuels: Exploring Reactivity from Molecular Structure

A total of 38 ionic liquids (19 of which are new) comprised of 13 cations, 1-propargyl-3-methyl-imidazolium, 1-allyl-3-methyl-imidazolium, 1,3-dimethyl-imidazolium, 1-ethyl-3-methyl-imidazolium, 1-butyl-3-methyl-imidazolium, 1-meth-oxyethyl-3-methyl-imidazolium, 1-methyl-4-butyl-1,2,4-triazolium, 1-methyl-4-allyl-1,2,4-triazolium, 1-methyl-4-amino-1,2,4-tri-azolium, <i>N</i>-butyl-<i>N</i>-methyl-pyrrolidinium, <i>N</i>-allyl-<i>N</i>-methyl-pyrrolidinium, <i>N</i>-allyl-pyridinium, and <i>N</i>-butyl-3-methyl-pyridinium, paired with three anions, dicyanamide, azide, and nitrocyanamide, have been prepared, characterized, and evaluated as potential hypergolic fuels by determining key physical, thermal, and ignition properties. The reactivity of these ionic liquids (32 liquids and 6 solids which melt below 100 °C) was strongly correlated to increased electron density in the cation, while small changes in physical properties had little effect beyond a certain threshold, suggesting that subtle changes in chemical reactivity can greatly influence the hypergolic ignition pathway