Unexpected Intrinsic Lability of Thiol-Functionalized Carboxylate Imidazolium Ionic Liquids

New thiol-functionalized carboxylate ionic liquids (ILs), varying both for the cation and for the anion structures, have been prepared as new potential redox switching systems by reacting either 3-mercapto propionic acid (3-MPA) or N-acetyl-cysteine (NAC) with commercially available methyl carbonate ILs. Dierent ratios of thiol/disulfide ILs were obtained depending both on the acid employed in the neutralization reaction and on the reaction conditions used. Surprisingly, the imidazolium ILs displayed limited thermal stability which resulted in the formation of an imidazole 2-thione and a new sulfide ionic liquid. Conversely, the formation of the imidazole 2-thione was not observed when phosphonium disulfide ILs were heated, thus confirming the involvement of the imidazolium ring in an unexpected side reaction. An insight into the mechanism of the decomposition has been provided by means of DFT calculations

A Specific Interaction between Ionic Liquids' Cations and Reichardt's Dye

Solvatochromic probes are often used to understand solvation environments at the molecular scale. In the case of ionic liquids constituted by an anion and a cation, which are designed and paired in order to obtain a low melting point and other desirable physicochemical properties, these two indivisible components can interact in a very different way with the probe. This is the case with one of the most common probes: Reichardt's Dye. In the cases where the positive charge of the cation is delocalized on an aromatic ring such as imidazolium, the antibonding orbitals of the positively charged aromatic system are very similar in nature and energy to the LUMO of Reichardt's Dye. This leads to an interesting, specific cation-probe interaction that can be used to elucidate the nature of the ionic liquids' cations. Parallel computational and experimental investigations have been conducted to elucidate the nature of this interaction with respect to the molecular structure of the cation

A general environmentally friendly access to long chain fatty acid ionic liquids (LCFA-ILs)

The development of bio-based ionic liquids (ILs) has attracted a great deal of interest in recent years. The so called long chain fatty acid ionic liquids (LCFA-ILs) represent a bio-based subfamily of hydrophobic ionic liquids. Here, a new preparation of the three major classes of LCFA-ILs (phosphonium, ammonium, imidazolium) is presented with the aim to overcome previous environmental synthetic issues. The undeniable interesting properties and potential applications of the LCFA-ILs often led to the underestimation of the drawbacks related to their synthetic pathways. Pure LCFA-ILs as well as cheaper mixture of LCFA-ILs have been obtained in a single step, in almost quantitative yields, and without production of waste water. The rheological and thermal stability properties of the prepared ILs have been analyzed

Ionic liquid-promoted green synthesis of biologically relevant diaryl thioethers

This study reports an ionic liquid (IL) promoted green method to obtain diaryl thioethers useful as key intermediates for the synthesis of matrix metalloproteinase (MMP) inhibitors. The synthetic pathway includes a sequential Ullmann reaction and Suzuki cross-coupling. The Ullmann conditions were optimized as regards the catalyst, the ionic liquid, reaction time, and temperature. Under optimal conditions (1-butyl-3-methylimidazolium bromide ([BMIM]Br) as solvent; catalyst, Cu; base, K2CO3; reaction time, 22 h; reaction temperature, 150°C) the aryl iodide conversion was 95%. The Suzuki cross-coupling was conducted in 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4) at 110°C, using Pd(PPh3)4 as catalyst and Na2CO3 as base. For both reactions, a combination of ILs with microwave (MW) irradiation determined a substantial improvement of reaction time and yields compared to conventional heating. This multi-step process reduces reaction times and removes organic solvents providing a more eco-friendly alternative for the synthesis of important pharmaceutical building blocks

Chiral ionic liquids supported on natural sporopollenin microcapsules

Supported chiral ionic liquids (SILs) were prepared choosing the starting material for the ionic liquid part from the enantiopure stock of the chiral pool (monoterpenoids and an amino acid) and the sporopollenin as an environmentally friendly support. Sporopollenins are microcapsules with naturally well-defined sizes and shapes that can be obtained from pollen grains after removal of the internal cytoplasm and the second shell layer. As thermally stable organic biocompatible structures, sporopollenins have attracted increasing interest in recent years for several applications. Herein, bio-based ILs were anchored onto the surface of sporopollenins obtained from the pollen of Populus deltoides, selected as a model pollen grain. These new structures, which present an external positively charged shell, were characterized by physico-chemical techniques (ATR-FTIR, TGA, SEM, EDX, and solid-state 13C NMR). A metathesis reaction was also performed on selected bio-based IL modified sporopollenins, demonstrating the possibility to switch the surface properties by exploiting well-known IL chemistry

Reorganization of Active Surveillance of Acute Flaccid Paralysis (AFP) in Emilia-Romagna, Italy: a two-step Public Health intervention

Background and aim of the work: The International Health Regulations Emergency Committee declared in 2014 that poliovirus circulation is a public health emergency of international concern. In 2017 and 2018 Italy was classified at intermediate risk of poliovirus reintroduction based on suboptimal poliovirus surveillance. Acute flaccid paralysis active surveillance is the gold standard in the polio eradication process. The aims of this study were to investigate the causes of reduced acute flaccid paralysis case reporting in Emilia-Romagna in the last few years (step 1) and to study a public health intervention to restore an adequate level of acute flaccid paralysis surveillance in that region (step 2). Methods: In the first step a context analysis was performed by analysing the 2015-2017 Hospital Discharge Registers in Emilia-Romagna with the ICD-9-CM differential diagnosis codes for acute flaccid paralysis. Data from context analysis was then used to plan a new regional collaborative network of acute flaccid paralysis active surveillance. Results: The active surveillance network was, at the end of the study, composed by 49 doctors from both hospital administrations and clinical wards from 4 University Hospitals and 7 Local Health Authorities throughout the Region. In 15 months, 7 acute flaccid paralysis cases have been reported; 85,7% received a full clinical and virological investigation and 83,3% completed the 60 day's follow-up. The mean response to each e-mail was 48,5% (SD 7,5%). Conclusions: In 2019, the Emilia-Romagna's active surveillance system reached the sensitivity, completeness of case investigation and follow-up required to achieve the minimum levels for certification standard surveillance

Lignin-Derivative Ionic Liquids as Corrosion Inhibitors

Corrosion is a significant problem that negatively affects a wide range of structures and buildings, resulting in their premature failure, which causes safety hazards and significant economic loss. For this reason, various approaches have been developed to prevent or minimize the effects of corrosion, including corrosion inhibitors. Recently, biobased inhibitors have gained a certain interest thanks to their unique properties, eco-friendliness, and availability. Among all the green precursors, lignin is of particular interest, being a natural polymer that can be obtained from different sources including agricultural residues. Corrosion inhibitors based on ionic liquids (ILs) also present interesting advantages, such as low volatility and high tunability. If combined, it may be possible to obtain new lignin-based ILs that present interesting corrosion inhibitor properties. In this work, the inhibition properties of new biobased lignin ILs and the influence of anions and cations on the corrosion of mild steel in an aqueous solution of 0.01 M NaCl were investigated by Potentiostatic Electrochemical Impedance Spectroscopy (PEIS) and Cyclic Potentiodynamic Polarization (CPP). Moreover, the surface was characterized using SEM, EDS, and optical profilometry. The IL choline syringate showed promising performance, reducing the corrosion current after 24 h immersion in 0.01 M sodium chloride, from 1.66 µA/cm2 for the control to 0.066 µA/cm2 with 10 mM of the IL present. In addition to its performance as a corrosion inhibitor, both components of this IL also meet or exceed the current additional desired properties of such compounds, being readily available, and well tolerated in organisms and the environment

Expanding the Chemical Space of Benzimidazole Dicationic Ionic Liquids

Benzimidazole dicationic ionic liquids (BDILs) have not yet been widely explored in spite of their potential. Therefore, two structurally related families of BDILs, paired with either bromide or bistriflimide anions and bearing alkyl spacers ranging from C3 to C6, have been prepared. Their thermal properties have been studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), while their electrical properties have been assessed by cyclic voltammetry (CV). TG analysis confirmed the higher stability of the bistriflimide BDILs over the bromide BDILs, with minor variation within the two families. Conversely, DSC and CV allowed for ascertaining the role played by the spacer length. In particular, the thermal behavior changed dramatically among the members of the bistriflimide family, and all three possible thermal behavior types of ILs were observed. Furthermore, cyclic voltammetry showed different electrochemical window (C3(C1BenzIm)2/2Tf2N < C4(C1BenzIm)2/2Tf2N, C5(C1BenzIm)2/2Tf2N < C6(C1BenzIm)2/2Tf2N) as well as a reduction peak potential, shape, and intensity as a function of the spacer length. The results obtained highlight the benefit of accessing a more structurally diverse pool of compounds offered by dicationic ILs when compared to the parent monocationic ILs. In particular, gains are to be found in the ease of fine-tuning their properties, which translates in facilitating further investigations toward BDILs as designer solvents and catalysts

Remarkable effect of [Li(G4)]TFSI solvate ionic liquid (SIL) on the regio- And stereoselective ring opening of α-gluco carbasugar 1,2-epoxides

Carba analogues of biologically relevant natural carbohydrates are promising structures for the development of future drugs endowed with enhanced hydrolytic stability. An open synthetic challenge in this field is the optimization of new methodologies for the stereo- and regioselective opening of α-gluco carbasugar 1,2-epoxides that allow for the preparation of pseudo mono- and disaccharides of great interest. Therefore, we investigated the effect of Lewis acids and solvate ionic liquids (SILs) on the epoxide ring opening of a model substrate. Of particular interest was the complete stereo- and regioselectivity, albeit limited to simple nucleophiles, toward the desired C(1) isomer that was observed using LiClO4. The results obtained with SILs were also remarkable. In particular, Li[NTf2]/tetraglyme ([Li(G4)]TFSI) was able to function as a Lewis acid and to direct the attack of the nucleophile preferentially at the pseudo anomeric position, even with a more complex and synthetically interesting nucleophile. The regioselectivity observed for LiClO4 and [Li(G4)]TFSI was tentatively ascribed to the formation of a bidentate chelating system, which changed the conformational equilibrium and ultimately permitted a trans-diaxial attack on C(1). To the best of our knowledge, we report here the first case in which SILs were successfully employed in a ring-opening process of epoxides

Exploiting Deep Eutectic Solvents and Ionic Liquids for the Valorization of Chestnut Shell Waste

The full utilization of agricultural waste and its recycle into a new chain of value are of primary importance for the development of a sustainable and profitable agricultural industry. Chestnut shell waste (CSW) is an interesting case of study, whose valorization has been though partially investigated to date. This work aims at exploring the complete utilization of CSW, in terms of obtaining both value-added compounds and enriched cellulose and lignin fractions. The results were obtained via the unreported combined use of two classes of nonconventional organic solvents, namely natural deep eutectic solvents and bio-based ionic liquids (bio-ILs). At first, combinations of choline chloride (ChCl)-based DESs with an acid, a polyol, or a sugar as hydrogen bond donors were employed for the extraction of polyphenols from the CSW. The best performing system was found to be ChCl:oxalic acid dihydrate (ChCl:Oax2H2O). The extraction efficiencies of the DESs tested correlate well with the measured Kamlet–Taft α parameters. After polyphenol removal, the residual solid material was treated with a bio-IL [cholinium glycinate (ChGly)] for further separation of lignin and cellulose. The products obtained by the fractionation process were characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis, which confirmed the separation of the residue into a lignin-rich material and a cellulose-rich material. The results obtained were further corroborated by a three parallel reaction model combined with the distributed activation energy model, which allowed for predicting the composition of the pristine CSW and of the ChCl:Oax2H2O-treated CSW as well as the two fractions obtained after ChGly treatment. The recyclability of the best performing DES and the recovery of the bio-IL have also been proven, which make the whole process viable and amenable for large-scale applications