Host—Guest Interactions Involving Cyclodextrins: Useful Complementary Insights Achieved by Polarimetry.

Abstract By means of simple polarimetry, we studied the binding abilities of native α-, β-, and γ-cyclodextrins toward a group of suitably chosen model guests. We were able to get reliable estimations of the binding constants K, spread over a wide range (from 3.7 to 12,300 M−1), allowing us to carry on interesting comparisons. A comprehensive discussion of polarimetric data, and in particular a detailed analysis of the variations ΔΘ of molar optical activities consequent to inclusion, offered us the opportunity to get useful insights into the structure and dynamic behavior of host–guest complexes.

Can the absence of solvation of neutral reagents by ionic liquids be responsible for the high reactivity in base-assisted intramolecular nucleophilic substitutions in these solvents?

[reaction: see text] The kinetics of the rearrangement of the Z-phenylhydrazone of 3-benzoyl-5-phenyl-1,2,4-oxadiazole (1a) into the relevant 4-benzoylamino-2,5-diphenyl-1,2,3-triazole (2a) induced by amines have been studied in two room-temperature ionic liquids (IL-1, [BMIM][BF4] and IL-2, [BMIM][PF6]). The data collected show that the reaction occurs faster in ionic liquids than in other conventional solvents previously studied (both polar or apolar, protic or aprotic). Presumably, this could depend on their peculiar ability to minimize the strong substrate-solvent, amine-solvent and amine-amine interactions occurring in conventional solvents.

Mononuclear rearrangement of heterocycles in ionic liquids catalyzed by copper(II) salts

Abstract The reactivity of E- and Z-phenylhydrazones of 3-benzoyl-5-phenyl-1,2,4-oxadiazole in the presence of CuCl2 and Cu(ClO4)2·6H2O has been studied in four imidazolium ionic liquids [bmim][X] (X=BF4−, PF6−, SbF6− and CF3SO3−). The reaction may follow different mechanistic patterns, depending on the nature of the ionic liquid anion, accounting for both qualitative and kinetic data. In the presence of CuCl2, two processes take place at the same time, i.e., the E⇆Z isomerization and the rearrangement of Z-isomer into the relevant 4-benzoylamino-2,5-diphenyl-1,2,3-triazole. In contrast, in the presence of Cu(ClO4)2·6H2O, the rearrangement occurs only in solution of [bmim][BF4] and [bmim][C…

Effects of packaging on shelf-life and quality of minimally processed fennel

Fennel is not a widespread product among minimally processed vegetables, due to the fast deterioration mainly caused by browning of the cut surfaces, even during cold storage. In order to extend the shelf-life of fresh-cut fennel, the influence of different packaging techniques was studied. Sliced fennel, dipped in a citric acid solution (0.5%), was placed in polystyrene trays, sealed with PE film or vacuum packaged in PE bags and stored up to 14 days at 4°C. During this period the weight loss, soluble solid content, pH, color and firmness were evaluated. Minimally processed fennel packed in sealed trays and cold-stored at 4°C, extended its shelf-life to 14 days maintaining acceptable quali…

Effetto dei sostituenti sulla reattività di alcuni Z-fenilidrazoni del 5-ammino-3-benzoil-1,2,4-ossadiazolo in diossano/acqua

The effect of the cation p-surface area on the 3D organization and catalytic ability of imidazolium-based ionic liquids

The dichotomic nature of ionic liquids (ILs, simple solvents or supramolecular fluids) induced us to carry out a structural investigation of some mono-and dicationic ionic liquids using 1D and 2D NMR, resonance light scattering, and UV/Vis spectroscopy. Ionic liquids with different cation π-surface areas were used, namely [bmim][NTf2], [Bzmim][NTf 2], [Bzbim][NTf2], [p-Xyl-(bim)2][NTf 2]2, and [m-Xyl-(bim)2][NTf2] 2 [bmim = 1-butyl-3-methylimidazolium, Bzmim = 1-benzyl-3- methylimidazolium, Bzbim = 1-benzyl-3-butylimidazolium, NTf2 = bis(trifluoromethansulfonyl)imide]. In order to verify to what extent the structural investigation, coupled with the determination of solvent parameters, could…

Task Specific Dicationic Ionic Liquids: Recyclable Reaction Media for the Mononuclear Rearrangement of Heterocycles

Nine functionalized dicationic ionic liquids were used to study the base catalyzed mononuclear rearrangement of (Z)-phenylhydrazone of 3-benzoyl-5-phenyl-1,2,4-oxadiazole into the corresponding triazole at 363 K. Ionic liquids were characterized by the presence of 1-(1-imidazolylmethyl)-3,5-di[1-(3'-octylimidazolylmethyl)]benzene cation, bearing on the structure a neutral imidazole unit as basic functionality. Besides anions generally used for monocationic ionic liquids, such as [Br(-)], [BF4(-)], and [NTf2(-)], also dianions having a rigid aromatic spacer such as 1,4-benzenedicarboxylate, 2,6-naphthalenedicarboxylate, and 1,5- and 2,6-naphthalenedisulfonate were taken into account. Further…

A joint experimental and ab initio study on the reactivity of several hydroxy selenides. Stereoselective synthesis of cis-disubstituted tetrahydrofurans via seleniranium ions

Abstract The reactivity of several hydroxy selenides bearing an ethereal chain with catalytic amounts of perchloric acid in dichloromethane was investigated. Results showed that the position of the oxygen atom with respect to the seleniranium ring was crucial in order to get a good yield of the cyclized product. The factors on which yields of the 5- endo cyclization of the seleniranium ions depend were analysed by ab initio (HF/3-21G ∗ ) studies. An explanation of the different coordinating ability, towards the positively charged selenium atom, of the allylic OMe and homoallylic OH-2 groups was given.

On the Rearrangement in Dioxane/Water of (Z)-Arylhydrazones of 5-Amino-3-benzoyl-1,2,4-oxadiazole into (2-Aryl-5-phenyl-2H-1,2,3-triazol-4-yl)ureas: Substituent Effects on the Different Reaction Pathways

We have recently evidenced an interesting differential behavior in the reactivity in dioxane/water between the (Z)-2,4-dinitrophenylhydrazone (1a) and the (Z)-phenylhydrazone (1b) of 5-amino-3-benzoyl-1,2,4- oxadiazole. The former rearranges into the relevant triazole 2a only at pS+ > 4.5 while undergoing hydrolysis at high proton concentration (pS+ < 3.5); on the contrary, the latter rearranges into 2b in the whole pS+ range examined (0.1 e pS+ e 14.9). Thus, for a deeper understanding of these differences we have now collected kinetic data on the rearrangement in dioxane/water of a series of 3- or 4-substituted (Z)-phenylhydrazones (1c-l) of 5-amino-3-benzoyl-1,2,4-oxadiazole in a wide ra…

Supported ionic liquid asymmetric cathalysis. A new method for chiral catalyst recycling

A new method for chiral catalysts recycling, based on the supported ionic liquid asymmetric catalysis concept, has been developed. This concept involves the treatment of a monolayer of covalently attached ionic liquid on the surface of silica gel with additional ionic liquid. These layers serve as the reaction phase in which the homogeneous chiral catalyst is dissolved. As first application of this concept the L-proline-catalyzed aldol reaction has been carried out. Good yields and ee values, comparable with those obtained under homogeneous conditions have been obtained. Moreover, this material shows high regenerability.

Amine basicity: measurements of ion pair stability in ionic liquid media

Abstract The stability constants relevant to the formation of amine/p-nitrophenol ion pairs have been determined in [bmim][BF4] solution, in the presence of butylamine, piperidine, and triethylamine, by using spectrophotometric measurements. In order to evaluate how the ion pair stability is affected by ionic liquid structure, piperidine has been chosen as model amine for studies in [bmim][PF6], [bmim][NTf2], [bm2im][NTf2] and in several [bmim][BF4]/1,4-dioxane binary mixtures. Data obtained in ionic liquid solutions have been compared with those previously reported in conventional organic solvents.

Hybrid ionogels: adsorbent for the removal of pharmaceutical active compounds from wastewater

Molecular “Pincer” from a Diimidazolium Salt: A Study of Binding Ability

The anion recognition ability of the dicationic imidazolium salt 3,3′-di-n-octyl-1,1′- (1,3-phenylenedimethylene)diimidazolium 1,5-naphthalenedisulfonate ([m-Xyl-(oim)2][1,5-NDS]) was investigated in acetonitrile solution by means of proton NMR titrations. A wide range of anions, comprising simple inorganic ions, halides, and mono- and dicarboxylates was taken into account. The study showed that this receptor binds carboxylate anions more strongly than halides. Moreover [m- Xyl-(oim)2][1,5-NDS] displays selectivity for di- over monocarboxylate anions. The complex stability was mainly affected by the anion basicity in the presence of monocarboxylates, whereas the flexibility of the alkyl cha…

Ionic liquid gels and antioxidant carbon nanotubes: Hybrid soft materials with improved radical scavenging activity

Hypothesis: Performances of materials are frequently affected by the action of radicals that can induce their degradation. To overcome the above issue, natural antioxidants (AOs) can be added during manufacturing. Considering the high instability of AOs, they have been adsorbed on carbon nanomaterials surface. However, the inclusion of functionalized carbon nanomaterials into gel matrix could enhance the antioxidant efficiency and represent an easy way to disperse and handle the active species.Experiments: Carboxypropyl functionalized carbon nanotubes (f-CNT), pure or with physically adsorbed alpha-tocopherol (f-CNT-VE) and quercetin (f-CNT-Q), were incorporated in some ionic liquid gels (I…

Carbon-based ionic liquid gels: alternative adsorbents for pharmaceutically active compounds in wastewater

With the aim of obtaining adsorbent systems to be used for the removal of pharmaceutically active compounds (PhACs) from wastewater, some hybrid ionic liquid gels (HILGs) were obtained from the combination of ionic liquid-based supramolecular gels and carbon materials, like graphite, graphene and graphene oxide (graphene OX). The properties of HILGs were investigated by determining their gel–sol transition temperature and rheological features. They were tested for the removal of PhACs belonging to different pharmaceutical classes, like antibiotics, antidepressants, anti-inflammatory. In particular, the removal of carbamazepine (CBZ), diclofenac sodium salt (DCF), ciprofloxacin (CPX) and nal…

Abilità organizzante di liquidi ionici: effetto sulla velocità di reazioni di trasposizione mononucleare di eterocicli.

TASK SPECIFIC IONIC LIQUIDS: CATALIZZATORI ECOCOMPATIBILI PER LA DEPOLIMERIZZAZIONE DELLE PLASTICHE

Binding properties of mono-(6-deoxy-6-amino)-β-cyclodextrin towards p-nitroaniline derivatives: a polarimetric study

Abstract Polarimetry was used in order to investigate the formation of supramolecular complexes between mono-6-amino-β-cyclodextrin and various p-nitroaniline derivatives at two different pH values. Comparison with the behaviour of native β-cyclodextrin gave us the opportunity to consider the effect exerted by the presence of charged groups, having different solvation requirements, on the binding equilibrium. Data offer some support to the hypothesis of ‘dynamic co-inclusion’ of solvent molecules within the host–guest complex.

Geminal Imidazolium Salts: A new Class of Gelators

The gelling behavior of some geminal diimidazolium salts was investigated in solvents differing in polarity and hydrogen bond donor ability. The used salts, namely the 3,3'-di-n-decyl-1,1'(1,4-phenylenedimethylene)diimidazolium dibromide [p-Xyl-(decim)(2)][Br](2) (1), the 3,3'-di-n-dodecyl-1,1'(1,4-phenylenedimethylene)diimidazolium dibromide [p-Xyl-(dodecim)(2)][Br](2) (2), and the 3,3'-di-n-dodecyl-1,1'(1,4-phenylenedimethylene)diimidazolium ditetrafluoroborate [p-Xyl-(dodecim)(2)][BF(4)](2) (3), differ in the alkyl chain length and in the anion properties, such as size, shape, and coordination ability. In all cases in which gelation process was observed, the obtained gels were characteri…

Amino acid-based cholinium ionic liquids as sustainable catalysts for pet depolymerization

Chemical recycling to monomers is one of the key strategies in tackling the issues deriving from persistent plastic pollution in the environment, and poly(ethylene terephthalate) (PET) is among the most used polymers in modern society. In this context, we herein describe the glycolysis of PET to bis-hydroxyethyl terephthalate (BHET), promoted by basic cholinium salts differing for the anions, also comprising amino acid anions. We investigated the optimal reaction conditions, finding that the best-performing catalyst is [Ch][Gly], in the presence of which a conversion of 85% and a yield of 51% are achieved at 150 °C after 6 h, from PET deriving from a clear water bottle. We used our protocol…

Polarity study of ionic liquids with the solvatochromic dye Nile Red: a QSPR approach using in silico VolSurf+ descriptors

The in silico VolSurfþ descriptors, accounting for both cationic and anionic structural features of ionic liquids (ILs) were used to develop a Partial Least Squares (PLS) model able to establish a Quantitative Structure Property Relationship (QSPR) correlation with their solvatochromic dye Nile Red polarity. The PLS model allowed prediction of ENR values for 116 ILs providing an in silico ILs polarity database.

Fluorescent interaction Eu-IL: when the anion plays a role

Cyclodextrins: heterocyclic molecules able to perform chiral recognition (Part II)

The present paper collects the most significant advances appeared since late 1998 up to June 2005 in the field of applications of natural and modified cyclodextrins as chiral selectors, with particular regard for pharmaceuticals and natural products.

ALTERNATIVES TO METHYL BROMIDE IN STRAWBERRY CULTIVATION

Multifunctional Carrier Based on Halloysite/Laponite Hybrid Hydrogel for Kartogenin Delivery

[Image: see text] A novel carrier system based on halloysite nanotubes (HNT), for the potential intraarticular delivery of kartogenin (KGN) by means laponite (Lap) hydrogel (HNT/KGN/Lap), is developed. The drug was first loaded into HNT, and the hybrid composite obtained was used as filler for laponite hydrogel. Both the filler and the hydrogel were thoroughly investigated by several techniques and the hydrogel morphology was imaged by transmission electron microscopy. Furthermore, the gelating ability of laponite in the presence of the filler and the rheological properties of the hybrid hydrogel were also investigated. The kinetic release of kartogenin from HNT and HNT/Lap hybrid hydrogel …

Functionalised Imidazolium Dicationic Ionic Liquids used as reaction media for base catalyzed organic reactions

Insights into the effect of the spacer on the properties of imidazolium based AIE luminogens

Abstract With the aim to obtain organic salts with potential applications in high performance molecular electronics, we combined properties of π-conjugated spacers, like 1,4-diethynylbenzene and 1,6-diethynylpyrene, with the ones of both imidazole and imidazolium units. Physico-chemical properties of obtained fluorescent organic salts were investigated performing thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC) and cyclic voltammetry measurements (CV). Photophysical behavior of the salts was analyzed in conventional solvents and ionic liquids, by UV–vis and fluorescence investigation. Solution phase aggregation study revealed that these salts self-assemble in conve…

The effects of structural changes on the anti-microbial and anti-proliferative activities of diimidazolium salts

An array of diimidazolium salts has been synthesized and used to investigate their anti-microbial and anti-proliferative activities. In particular, salts based on the 3,30-di-n-alkyl-1,10-(1,n-phenylenedimethylene)- diimidazolium cation and differing in the alkyl chain length on the imidazolium ion, the isomeric substitution on the aromatic spacer and in the anion nature were used. The anti-proliferative activity was evaluated against cervical (HeLa), colon adenocarcinoma (HT-29) and breast (SKBR3) cancer cell lines. In the latter case, also a morphological assessment after treatment with salts was performed. All salts were tested for their hemolytic activity against human erythrocytes. On …

Host-guest interactions between DMpillar[5]arene and fluorescent imidazolium salts

Reattività dello Z-fenilidrazone del 5-ammino-3-benzoil-1,2,4-ossadiazolo in toluene in presenza di acidi aloacetici.

Determinazione di costanti di formazione di coppie ioniche in liquidi ionici

Ionic liquids: a highway with many lanes

Two-Component Hydrogels Formed by Cyclodextrins and Dicationic Imidazolium Salts

In the framework of our recent interest in studying the gelling behaviour of imidazolium salts, we took into account the possibility of obtaining two-component hydrogels by combining cyclodextrins and dicationic imidazolium salts. In particular, we used diimidazolium salts differing in the alkyl chain length and in the size, shape, and coordination ability of the anion, namely the 3,3′-di-n-decyl- and 3,3′-di-n-dodecyl-1,1′-(1,4-phenylenedimethylene)diimidazolium dibromide, and 3,3′-di-n-dodecyl-1,1′-(1,4-phenylenedimethylene)diimidazolium ditetrafluoroborate and dihexafluorophosphate. As far as cyclodextrins are concerned, to gain information on the effects of different sized cyclic oligos…

Insights into the Formation and Structures of Molecular Gels by Diimidazolium Salt Gelators in Ionic Liquids or “Normal” Solvents

Insights are provided into the properties of molecular gels formed by diimidazolium salts both in “normal” solvents and ionic liquids. These materials can be interesting for applications in green and sustainable chemistry in which ionic liquids play a significant role, like catalysis and energy. In particular, two positional isomers of a diimidazolium cation have been examined with a wide range of anions for their ability to form gel phases. In particular, di-, tri-, and tetravalent anions bearing aliphatic or aromatic spacers were paired with the divalent cations. The properties of the organo- and ionogels formed have been analyzed by means of several different techniques, including calori…

Ionic Liquids Binary Mixtures: Promising Reaction Media for Carbohydrates Conversion in 5-HMF

Polarimetric study of binding equilibria between cyclodextrins and some suitable organic guests

Anion and ionic liquid effects on ionogel phases formation

Geminal organic salts have been recently introduced as the third generation of ionic liquids.1 Like their monocationic precursors they generally show high thermal stability and low corrosiveness, as well as high polarity and structural order degree.2 All these features make them good candidates to be used in the formation of conductive gel phases, that afterwards may find application as organized reaction media or in the preparation of dye sensitized solar cells.3 In this context, we have recently synthesized some task specific geminal organic salts and investigated their behaviour as gelators. The obtained salts were able to gel ionic liquid solutions. In order to have information about th…

Acid- and Base-Catalysis in the Mononuclear Rearrangement of Some (Z)-arylhydrazones of 5-Amino-3-benzoyl-1,2,4-oxadiazole in Toluene: Effect of Substituents on the Course of Reaction

The reaction rates for the rearrangement of eleven (Z)-arylhydrazones of 5-amino-3-benzoyl-1,2,4-oxadiazole 3a-k into the relevant (2-aryl-5-phenyl-2H-1, 2,3-triazol-4-yl)ureas 4a-k in the presence of trichloroacetic acid or of piperidine have been determined in toluene at 313.1 K. The results have been related to the effect of the aryl substituent by using Hammett and/or Ingold-Yukawa-Tsuno correlations and have been compared with those previously collected in a protic polar solvent (dioxane/water) as well as with those on the analogous rearrangement of the corresponding (Z)-arylhydrazones of 3-benzoyl-5-phenyl-1,2,4-oxadiazole 1a-k in benzene. Some light can thus be shed on the general di…

Supported Ionic Liquid Asymmetric Catalysis. A New Method for Chiral Catalysts Recycling. The Case of Proline-Catalyzed Aldol Reaction.

A new method for chiral catalysts recycling, based on the supported ionic liquid asymmetric catalysis concept, has been developed. This concept involves the treatment of a monolayer of covalently attached ionic liquid on the surface of silica gel with additional ionic liquid. These layers serve as the reaction phase in which the homogeneous chiral catalyst is dissolved. As first application of this concept the L-proline-catalyzed aldol reaction has been carried out. Good yields and ee values, comparable with those obtained under homogeneous conditions have been obtained. Moreover, this material shows high regenerability.

Two component chiral gels: a study of properties and behavior as recognition systems

Protonazione del p-nitrofenato di sodio in liquidi ionici: una "sonda" per la determinazione della forza acida

A competitive reactivity study on the oxidative cyclization of thiosemicarbazones into 1,3,4-thiadiazoles

Abstract In order to obtain useful insights on the mechanism of formation of 2(3H)-imino-1,3,4-thiadiazoles by oxidative cyclization of aldehyde thiosemicarbazones with Cu(II) or Fe(III) salts, a competitive reactivity study was performed on a suitable set of diversely substituted substrates, by means of HPLC techniques. This approach enabled to exploit Hammett’s equation without performing otherwise difficult-to-run kinetic experiments. The results presented herein support the hypothesis that the formation of the thiadiazole ring is induced by the attack of the oxidizing Lewis acid metal cation onto the imine-like nitrogen atom of the thiosemicarbazone substrate. Beyond mechanistic interpr…

Supramolecular Hydro- and Ionogels: A Study of Their Properties and Antibacterial Activity.

Diimidazolium-based organic salts, bearing peptides or amino acids as anions have been synthesised and tested for their gelling ability in biocompatible solvents. These low molecular weight salts were successfully used as gelators in phosphate buffered saline (PBS) solution and ionic liquids. Then, the properties of the obtained soft materials were analysed in terms of melting temperature and gel strength as accounted for by rheological investigations. The gel-phase formation was studied by using UV/Vis and resonance light scattering measurements, whereas the morphology of the soft materials was analysed by using polarised optical microscopy and scanning electron microscopy. To get informat…

Tunable radical scavenging activity of carbon nanotubes through sonication

Abstract Carbon nanotubes (CNTs) having controlled radical scavenging activity have been achieved tuning the content of their lattice defects induced by an ultra-sound (us) treatment. The reactivity of CNTs, subjected to ultra-sonication for different time intervals, toward 1,1-diphenyl-2-pycryl (DPPH) and hydroxyl (•OH) radicals has been estimated and related to defect concentration, evaluated through Raman spectrometry. The radical scavenging efficiency of ultra-sound treated CNTs (us-CNTs) increases with increasing the content of the structural defects, suggesting that the defect resulting from us treatment can be capitalized to obtain an amplified and controlled radical scavenging activ…

On the application of the extended Fujita-Nishioka equation to polysubstitued system. A kinetic study of the rearrangement of several poly-substitued Z-arylhydrazones of 3-benzoyl-5-phenyl-1,2,4-oxadiazole into 2-aryl-4-benzoylamino-5-phenyl-1,2,3-triazoles in dioxane/water

Abstract The rearrangement rates of several di-, tri-, tetra- or penta-substituted Z -arylhydrazones of 3-benzoyl-5-phenyl-1,2,4-oxadiazole ( 1a – 18a ) into the relevant 2-aryl-4-benzoylamino-5-phenyl-1,2,3-triazoles ( 1b – 18b ) have been determined in 1:1 (v:v) dioxane/water in a wide range of p S + (3.80–12.50) at different temperatures. The kinetic data obtained have been correlated with those previously collected for the rearrangement of ortho -, meta - and para -substituted Z -arylhydrazones ( 19a – 38a ) by means of an extension of the linear free-energy relationship (LFER) proposed by Fujita and Nishioka, thus considering steric ( E s ) and field ( F o ) proximity effects in additi…

Chemo-enzymatic Conversion of Glucose in 5-Hydroxymethylfurfural: The Joint Effect of Ionic Liquids and Ultrasound

For the valorization of lignocellulosic biomass, a key step is unlocking the conversion of glucose to suitable chemical platforms. To this aim, we herein describe the sequential chemo-enzymatic conversion of glucose into 5-hydroxymethylfurfural (5-HMF), in two steps: glucose isomerization to fructose, catalyzed by glucose isomerase (GI) and fructose dehydration to 5-HMF promoted by Amberlyst 15. The novelty of our approach lies in the use of crude cell extracts of Streptomyces coelicolor showing GI activity, as isomerization catalysts, along with a commercial immobilized GI. Under optimized reaction conditions, we obtained a conversion to 5-HMF (C5‑HMF) from glucose of 50% in the H2O/[bmim]…

p-Nitrophenolate: A Probe for Determining Acid Strength in Ionic Liquids

In order to obtain an acidity scale in room-temperature ionic liquid solutions, the protonation equilibrium of sodium p-nitrophenolate in [bm(2)im][NTf(2)] and in [bmpyrr][NTf(2)], at 298 K, has been studied by means of spectrophotometric titration. Carboxylic acids differing in both structure and in water solution strength have been used. Data collected indicate that in the analyzed ionic liquid solutions carboxylic acids are less dissociated than in water solution. Furthermore, by virtue of a mutual interaction, the studied equilibrium seems to be affected by both the nature of the ionic liquids and the carboxylic acids.

STABILITY AND ORGANOCATALYTIC EFFICIENCY OF N-HETEROCYCLIC CARBENES ELECTROGENERATED IN ORGANIC SOLVENTS FROM IMIDAZOLIUM IONIC LIQUIDS

The kinetic of degradation of 1-butyl-3-methylimidazole-2-ylidene (selected as model N-heterocyclic carbene - NHC), generated in organic solvents by cathodic reduction of the parent 1-butyl-3- methylimidazolium salts BMIm-X, was studied by a simple voltammetric analysis. The effect of NHC degradation rate on the efficiency of an organocatalyzed reaction (the synthesis of g-butyrolactone from cinnamaldehyde and trifluoromethylacetophenone) was investigated. The nature of the solvent and of the anion X have a remarkable effect on the stability of the NHC, the bis(trifluoromethylsulfonyl) imide anion being the best for a long lasting carbene (while acetonitrile seems to be the worst solvent). …

A magnetic self-contained thermochromic system with convenient temperature range

A new ionic liquid with sugar-based ligand has been prepared and used to coordinate cobalt(II), at low loading, in an ionic liquid solution. The system obtained reveals magnetic switching and marked thermochromism in solution/polymer films over a convenient temperature range (20–60 °C). This system is self-contained, devoid of any volatile substances, and reproducible over multiple thermal cycles. The colour change can be attributed to a change in the coordination geometry from octahedral (pink) at room temperature to tetrahedral (blue) on warming, monitored by 59Co NMR spectroscopy, which was used for the first time to study the change. This material may find applications in stimuli-respon…

Two components organogels as molecular recognition systems: properties, behavior and future applications

Functionalised diimidazolium salts: the anion effect on the catalytic ability

The catalytic ability of some functionalised diimidazolium ionic liquids was tested using the Michael addition of malononitrile to t-chalcone as probe reaction. Diimidazolium salts characterized by the presence of 1-(1-imidazolylmethyl)-3,5-di-[1-(3-octylimidazolylmethyl)]benzene cation and differing in the anion structure were used. Both mono- and dianions were employed and among these some chiral anions generally used as organocatalysts were taken into account. Data collected were analysed both as function of ionic liquids structure and basicity, evaluated using the Hammett basicity function. Although the use of chiral anions did not allow performing a stereochemical control of the reacti…

Naphthalimide imidazolium-based supramolecular hydrogels as bioimaging and theranostic soft materials

1,8-Naphthalimide-based imidazolium salts differing for the alkyl chain length and the nature of the anion were synthesized and characterized to obtain fluorescent probes for bioimaging applications. First, their self-assembly behavior and gelling ability were investigated in water and water/dimethyl sulfoxide binary mixtures. Only salts having longer alkyl chains were able to give supramolecular hydrogels, whose properties were investigated by using a combined approach of fluorescence, resonance light scattering, and rheology measurements. Morphological information was obtained by scanning electron microscopy. In addition, conductive properties of organic salts in solution and gel state we…

SALI ORGANICI: “TECTONI” PER LO STUDIO DI PROCESSI DI SELF-ASSEMBLY IN SOLVENTI ORGANICI

Supported ionic liquids. New recyclable materials for L-proline-catalyzed aldol reaction

Effect of ionic liquid organizing ability and amine structure on the rate and mechanism of base induced elimination of 1,1,1-tribromo-2,2-bis(phenyl-substituted)ethanes

Abstract The kinetics of the elimination reaction of 1,1,1-tribromo-2,2-bis(phenyl-substituted)ethanes into the corresponding 1,1-dibromo-2,2-bis(phenyl-substituted)ethenes induced by amines were studied in three room temperature ionic liquids ([BMIM][BF 4 ], [BMIM][PF 6 ], [BdMIM][BF 4 ]). In order to have information about reagent–ionic liquid interactions, the reaction was carried out over the temperature range (293.1–313.1 K). To study the effect of the amine on the rate and occurrence of the elimination reaction, several primary, secondary and tertiary amines with different structure (cyclic and acyclic), basicity and steric requirements were used. The data collected show that the reac…

Reazioni di isomerizzazione e trasposizione di fenilidrazoni in liquidi ionici: catalisi da sali di rame (II)

Stereoselective synthesis: from organoselenium to organocatalysis

Studies on the Stereoselective Selenolactonization, Hydroxy and Methoxy Selenenylation of α- and β-Hydroxy Acids and Esters. Synthesis of δ- and γ-Lactones.

Abstract The diastereoselective synthesis of hydroxy substituted γ- and δ-lactones was accomplished following two approaches. A 5- or 6-endo cyclization promoted by electrophilic selenium reagents of α- or β-hydroxy acids and a 5- or 6-exo cyclization of hydroxy esters obtained through a diastereoselective hydroxy selenenylation reaction of α- or β-hydroxy esters. Moreover, the diastereoselective methoxy selenenylation of the above compounds was investigated showing a case in which the compound that was unreactive in the hydroxy selenenylation conditions gave, in the methoxy selenenylation conditions, the deprotected diol. The usefulness of the methoxy selenenylation procedure was proven by…

Room temperature ionic liquids structure and its effect on the mononuclear rearrangement of heterocycles: an approach using thermodynamic parameters.

The kinetics of the rearrangement of the Z-phenylhydrazone of 3-benzoyl-5-phenyl-1,2,4-oxadiazole (1) into the relevant 4-benzoylamino-2,5-diphenyl-1,2,3-triazole (2) induced by amines have been studied in five room-temperature ionic liquids (RTILs) at different temperatures. The kinetic data collected show that both cationic and anionic parts of RTILs significantly influence the reactivity of the title reaction. The calculated activation parameters allow us to advance hypotheses about the weak interactions operating in RTIL solutions.

Ionic Liquids binary mixtures: the influence of the composition on their properties and catalytic ability

Diimidazolium organic salts and supramolecular gels exerting antimicrobial activity

Synthesis and characterization of new polyamino-cyclodextrin materials.

With the aim of the synthesis of chemically modified cyclodextrins bearing polyamine pendant groups, potentially useful as capping agents for the preparation of nanosized metal systems or as auxiliaries for gene transfection, the reaction between the heptakis-(6-iodo)-(6-deoxy)-b-cyclodextrin and various polyamines has been explored. This synthetic approach allows obtaining materials constituted by mixtures of cyclodextrins, having different degrees of substitution, which were satisfactorily characterized by means of various complementary techniques (ESI-MS, NMR, potentiometric titration). The products obtained were successfully subjected to preliminary tests for their binding abilities tow…

“Sweet” ionic liquid gels: materials for sweetening of fuels

The search for new materials to be used in desulfurisation (sweetening) of fuels is one of the main topics of current research. In this paper, we explored the possibility of using supramolecular gels obtained from the gelation of ionic liquid binary mixtures. Indeed, some ionic liquids are generally known as efficient extraction phases for desulfurisation of fuels. In rare cases, one of their main drawbacks is their partial solubility in the fuel, leading to contamination. Then, their immobilisation due to the formation of a gelatinous network may be a challenge. Ionic liquid gels were obtained by mixing certain [NTf2]−-based ionic liquids (solvents) with the ones of gluconate-based ionic l…

Reazione di eliminazione di Kemp: una sonda per lo studio delle proprietà microscopiche di liquidi ionici

Studio cinetico della reazione di eliminazione di 1,1,1-tribromo-2,2-bis(dimetossifenil)etano in liquidi ionici.

When the functionalisation comes in useful: ionic liquids with a “sweet” appended moiety demonstrate drastically reduced toxicological effects

The growing number of applications of ionic liquids (ILs) in industry have brought attention to the green credentials of synthesis, as well as their cytotoxicities and ecotoxicities both for their use and accidental leakage into the environment. With the abovementioned properties in mind, we designed a class of ILs with either cations bearing a gluconamide motif and aliphatic side chains or the anion incorporating a gluconic acid (derived from food waste) moiety. An IL with an imidazolium cation with an appended gluconic amide (bearing five hydroxyl groups) moiety was also synthesized for a useful comparison. Different structural features were considered, placing emphasis on the nature and …

The importance of supramolecular reaction media in catalysis

New “AIE” Luminogens based on π-conjugated imidazolium salts

Apolar versus polar solvents: a comparison of the strength of some organic acids against different bases in toluene and in water

The constants of ion-pair formation with 3-nitroaniline (3NO(2)A) for eight halogenoacetic acids (HAAs, 3a-h: TFA, TCA, TBA, DFA, DCA, DBA, MCA, and MBA), and five 2,2-dichloroalkanoic acids containing 3-8 carbon atoms (HAs, 5a-e: DCPA, DCBA, DCMBA, DCVA, and DCOA) have been determined in TOL at 298.1 K. The results obtained brought to evidence for HAAs the formation of ion-pairs with two different stoichiometries (base-acid, 1:1 or 1:2), while in contrast the HAs furnish only the 1:1 pairs. The different steric and electronic requirements of HAAs and HAs seem to be responsible for such an unlikely behavior. At the same time, the acid-catalyzed MRH of the (Z)-phenylhydrazone of 5-amino-3-be…

Protonation equilibria of some ortho-substituted and annelated aryl and thiophen-2-yl and -3-yl ketones

For some phenyl- (1–8) and thiophen-2-yl (9–11) and thiophen-3-yl (12–14) ketones quantum-mechanical (PM3) calculations have been performed, and for compounds 2, 3, 5–8, 10–14 protonation equilibria have been determined. Phenyl ketones have similar values for the m* parameter and show good linear correlation between the proton affinities calculated in the gas phase and the measured pKBH+ values, which in turn parallel the trend for the calculated carbonyl–phenyl ring dihedral angle. It appears that the differences in basicity are governed essentially by “internal” factors (carbonyl–ring conjugation), while the base–conjugate acid differential solvation is not significantly affected by struc…

Organizzazione strutturale di liquidi ionici mono- e dicationici: un approccio combinato

Diimidazolium-based organic salts as low molecular weight hydro- and organogelator

Ring-to-ring interconversion: a reactivity study of some substituted Z-phenylhydrazones of the 5-amino-3-benzoyl-1,2,4-oxadiazole.

"Sweet" Ionic Liquids Gels: Properties and Applications

Wo3 and ionic liquids: A synergic pair for pollutant gas sensing and desulfurization

This review deals with the notable results obtained by the synergy between ionic liquids (ILs) and WO3 in the field of pollutant gas sensing and sulfur removal pretreatment of fuels. Starting from the known characteristics of tungsten trioxide as catalytic material, many authors have proposed the use of ionic liquids in order to both direct WO3 production towards controllable nanostructures (nanorods, nanospheres, etc.) and to modify the metal oxide structure (incorporating ILs) in order to increase the gas adsorption ability and, thus, the catalytic efficiency. Moreover, ionic liquids are able to highly disperse WO3 in composites, thus enhancing the contact surface and the catalytic abilit…

STABILITY OF ELECTROGENERATED N-HETEROCYCLIC CARBENES FROM IONIC LIQUIDS. THE BOUNDARY CONDITIONS

Task-specific dicationic ionic liquids used as reaction media for Michael addition

The “perturbative” effect of cosolvents on the structure of neat bmimBF4 and bmimNTf2 evaluated by means of kinetic measurements.

Cyclodextrin-[60]fullerene conjugates: synthesis, characterization, and electrochemical behavior

Three different functionalized β-cyclodextrins (β-CDs) bearing the C60 moiety linked covalently have been prepared in good yields by reaction between the parent β-CD and [60]fullerene via 1,3-dipolar cycloaddition. These compounds have been fully spectroscopically characterized and their electrochemical behavior has been investigated. Surprisingly, the electrochemical properties of the C60 cage remain unaltered even after chemical functionalization, making these systems very appealing as supramolecular hosts for electron-transfer processes.

Catalisi da Cu(II) nelle reazioni di interconversione di anello: uno studio meccanicistico.

Reactivity of phenylhydrazones in ionic liquids solution: the effect of copper(II) salts

π-Conjugated diimidazolium salts: rigid structure to obtain organized materials.

Phenylene ethynylene based diimidazolium salts differing in the alkyl chain length borne on the imidazolium ion and anion nature were synthesized. Their properties were studied both in solution and in the solid state. Salts obtained were able to aggregate in organic solvent solution. Aggregate formation was studied by performing concentration dependent measurements using UV-vis, fluorescence and Resonance Light Scattering. Furthermore, features of the aggregates were also investigated in the solid state by means of fluorescence and Scanning Electron Microscopy measurements. Finally, Density Functional Theory calculations were performed to obtain insights into the interaction geometry in the…

Ionic Liquids-Cobalt (II) Thermochromic Complexes: How the Structure Tunability Affects "Self-contained" Systems

With the aim of obtaining thermochromic systems with potential applications in solar energy storage, we evaluated the behavior of some sugar-based ionic liquids (ILs)–Co(NTf₂)₂ complexes, in IL solution, as a function of temperature. Different structural changes on the cation, the nature of the anion, and the nature of the IL used as the solvent were considered. The analysis of the above factors was carried out through a combined approach of different techniques, that is, variable temperature UV–vis and NMR spectroscopies, conductivity, and thermal gravimetric analysis. The thermochromic systems were analyzed both as solutions and as thin films, and the data collected highlight the defining…

Binary Mixtures of Ionic Liquids: A Joint Approach to Investigate their Properties and Catalytic Ability

The growing interest in the properties and applications of ionic liquids has recently led to research into the possibility of using their binary mixtures. This work reports on the effects of binary mixtures of ionic liquids on the outcome of organic reactions such as the mononuclear rearrangement of heterocycles and the solvatochromic behavior of Nile Red. Binary mixtures formed by ionic liquids differing in the structure of the cation and the anion are taken into account. In particular, ionic liquids such as 1-benzyl-3- butylimidazolium bis(trifluoromethanesulfonyl)imide, 1-(2,3,4,5,6- pentafluorobenzyl)-3-butylimidazolium bis(trifluoromethanesulfonyl)imide, and 1-benzyl-3-butylimidazolium…

Studio cinetico della reazione di sostituzione nucleofila aromatica di alcuni 2-X-3-nitro e 2-X-5-nitrotiofeni in BMIMBF4.

New recyclable materials for L-proline-catalyzed aldol reactions

A spectrofluorimetric study of binary fluorophore-cyclodextrin complexes used as chiral selectors

Abstract Six binary complexes between three fluorophores (pyrene, xanthone and anthraquinone) and β-cyclodextrin (β-CD) or heptakis-(6-amino)-(6-deoxy)-β-cyclodextrin (am-β-CD) were tested at two pH values (8.0 and 9.0) as chiral selectors for three α-amino acids chosen as model. The conditional constant (β2T) values for ternary complexes (fluorophore-CD-amino acid), determined by means of fluorescence spectroscopy, showed that the binary complexes are suitable receptors for chiral recognition. The effect of α-amino acids on stability and stoichiometric ratio of the binary complexes has also been studied. The binary complexes were in most cases stabilized by adding the ternary agent. The tr…

Spectrophotometric study on the thermodynamics of binding of α- and β-cyclodextrin towards some p-nitrobenzene derivatives

Binding properties of native alpha- and beta-cyclodextrin towards some nitrobenzene derivatives have been studied by means of UV-vis spectrophotometry. The former host is able to form complexes having 1 : 1 and 1 : 2 stoichiometric ratios with these guests, while only 1 : 1 complexes are detected with the latter host. A careful analysis of the thermodynamic parameters for complexation equilibria, under the perspective of the enthalpy-entropy compensation effect, reveals that binding abilities of the two different hosts are subject to different features.

ChemInform Abstract: Di- and Tricationic Organic Salts: An Overview of Their Properties and Applications

During recent years growing interest has been devoted to the synthesis and applications of polycationic organic salts. Among them, di- and tricationic organic salts can be considered the natural evolution of monocationic ones. These last have given rise to the large class of ionic liquids. In the cases of di- and tricationic organic salts, the potential to change their structural features simply by varying the properties either of the charged heads or of the spacers separating them provides the opportunity to obtain materials suitable for different applications. This review article highlights recent progress in the study of the properties of di- and tricationic organic salts, as well as in …

Polarimetry as a useful tool for the determination of binding constants between cyclodextrins and organic guest molecules

Binding constants for cyclodextrin inclusion complexes can be easily estimated by means of simple polarimetric measurements. Determinations are as reliable and accurate as those obtained by means of other more sophisticated techniques, and take advantage by the limited waste of material required. Our results are briefly compared with literature values obtained by means of different techniques.

Complexation equilibria between beta-cyclodextrin and p-nitroaniline derivatives in mixed solvent media: a polarimetric study

Sali di dialchilimidazolio: dai liquidi ionici agli organogel

New examples of specific base catalysis in mononuclear rearrangements of heterocycles found via a designed modification of the side chain structure

To select suitable candidates for the occurrence of specific-base-catalysis in MRH of (Z)-hydrazones of 3-benzoyl-5-phenyl-1,2,4-oxadiazole we have designed a modification of the side-chain structure by linking a strong electron-withdrawing system to the hydrazono group. Thus we have synthesized the (Z)-semicarbazone (3d), the (Z)-phenylsemicarbazone (3e), and the (Z)-acetylhydrazone (3f) of the above oxadiazole and examined their kinetic behavior in dioxane/water in a large range of proton concentrations (pS + 4.0 14.5). In all the pS+ range examined only a base-catalyzed process has been evidenced (no uncatalysed path occurs). The behavior at the largest pS+ values (the reactivity tends t…

A joint of experimental investigations about the structural organization of two geminal ionic liquids

Geminal Ionic Liquids: A Combined Approach to Investigate their Tridimensional Structure

Different investigations, such as 1D and 2D NMR spectroscopy, resonance light scattering spectroscopy and molecular dynamics simulations, have been jointly used to achieve a deeper understanding of the degree of structural order in two geminal ionic liquids. In particular, 3,3’-di-n-butyl-1,1’-(1,3- phenylenedimethylene)diimidazolium and 3,3’-di-n-butyl-1,1’-(1,4-phenylenedimethylene) diimidazolium bis- ACHTUNGTRENUNG[bis(trifluoromethanesulfonyl)imide] have been studied. These geminal ionic liquids were chosen because of the presence of both a rigid phenylenedimethylene link between two imidazolium rings, which should give a high degree of order to the solvent system, and the different sha…

Ionogels formed by geminal imidazolium salts: a preliminary investigation

Geminal Ionic Liquids: an electrochemical approach to investigate their reactivity and stability vs. traditional monocationic ionic liquids

Substituent effects on the mechanism changeover in a multipathway reaction: A model for the behavior of biological systems?

By studying the rearrangement in dioxane/water of a series of (Z)-arylhydrazones of 5-amino-3- benzoyl-1,2,4-oxadiazole (1a-k) into the relevant (2-aryl-5-phenyl-2H-1,2,3-triazol-4-yl)ureas (2a-k) in a wide range of pS + (an operational scale of proton concentration in the mixed solvent used; dioxane/water, 1:1, v:v), the occurrence of three different reaction pathways (specific-acid- catalyzed, uncatalyzed, and general-base-catalyzed) for the relevant SNi process has been recently enlightened. The significantly different substituent effects on the three pathways cause some crossovers in the log kA,R versus pS + plots. Both the pS + value at which the crossover occurs and the width of the u…

Polarimetry as a useful tool for the study of binding equilibria between cyclodextrins and some suitably sized and structured organic molecules

Nitrogen-Doped Carbon Nanodots-Ionogels: Preparation, Characterization, and Radical Scavenging Activity

Hybrid diimidazolium-based ionogels were obtained by dispersing nitrogen-doped carbon nanodots (NCNDs) in ionic liquid (IL) solutions and by using dicationic organic salts as gelators. The properties of the NCND-ionogels were studied in terms of thermal stability, mechanical strength, morphology, rheological, and microscopic analyses. Insights into the formation of the hybrid soft material were attained from kinetics of sol-gel phase transition and from estimating the size of the aggregates, obtained from opacity and resonance light-scattering measurements. We demonstrate that, on one hand, NCNDs were able to favor the gel formation both in the presence of gelating and nongelating ILs. On t…

Reattività degli Z-idrazoni, semicarbazoni e fenilsemicarbazoni del 3-benzoil-5-fenil-1,2,4-ossadiazolo: effetto della struttura della catena laterale

Interplay of acidity and ionic liquid structure on the outcome of a heterocyclic rearrangement reaction

The study of suitable probe reactions is a powerful tool to investigate the properties of nonconventional solvents such ionic liquids (ILs). In particular, we studied the acid-catalyzed mononuclear rearrangement of heterocycles (MHR) of the Z-phenylhydrazone of 5-amino-3-benzoyl-1,2,4-oxadiazole into the relevant 1,2,3-triazole, in solution of ILs by means of kinetic measurements. We chose as solvents six ILs differing both in the cation and anion, in the presence of five carboxylic and sulfonic acids as catalysts. For a useful comparison, the reaction was also performed in 1,4-dioxane and methanol. In general, the reaction occurs faster in ILs, compared to conventional solvents, according …

Activity of a Heterogeneous Catalyst in Deep Eutectic Solvents: The Case of Carbohydrate Conversion into 5-Hydroxymethylfurfural

Obtaining industrially relevant products from renewable resources and developing processes under the light of sustainable chemistry is a prominent endeavor of present-day chemical research. In this context, herein we investigated the dehydration of fructose and sucrose in deep eutectic solvents promoted by the ion-exchange resin Amberlyst 15 as heterogeneous catalyst. We optimized the reaction conditions in terms of temperature, catalyst loading, and initial amount of substrate. Then, we looked at the effect of structural variations in the solvent components on the reaction outcome. Under the best experimental conditions, we obtained very good yields of 78% at 60 °C and 69% at 80 °C for fru…

Studio spettrofotometrico della formazione di coppie ioniche ammina/p-nitrofenolo in liquido ionico

A study of synergetic effect of ionic liquids and ultrasounds on the aryl azides formation

Influenza dei liquidi ionici sulla reazione di trasposizione eterociclica mononucleare catalizzata da Cu(II)

Stability and stoichiometry of some binary fluorophore-cyclodextrin complexes

The stability and stoichiometric ratio of binary complexes among five fluorophores and β-cyclodextrin (β-CD) or heptakis-(6-amino-6-deoxy)-β-cyclodextrin (am-β-CD) were determined by means of fluorescence measurements in borate buffer at pH=8.0 and 9.0. Structure of both host and guest affected the characteristics of the binary complexes. Pyrene and anthraquinone formed a 1:2 (fluorophore: cyclodextrin) complex with both cyclodextrins. Xanthone formed 1:1 complex with β-CD and 1:2 complex with am-β-CD. A more defined behaviour was observed for crysene. In fact, both stoichiometric different complexes were detected with both hosts. Only 1:1 complexes were observed for antracene. The complex …

Catalisi da sali di Cu(II) nelle reazioni di trasposizione eterociclica mononucleare.

Organogel formed by imidazolium salts: molecular recognition processes

Organic salts and aromatic substrates in two-component gel phase formation: the study of properties and release processes

To identify gel phases able to act as confined reaction media or materials for the removal of organic pollutants, we studied two-component gel phases formed by naphthalenedisulfonate diimidazolium salts in the presence of some organic guests, in 1-propanol solution. Guests differing in π-surface area, bulkiness and electronic properties were taken into account. Soft materials obtained were investigated for their thermal stability, self-repairing ability and morphology. Furthermore, two-component gel phase formation was studied using resonance light scattering (RLS) measurements. Guest release processes from the gel phase were also studied. These processes were monitored as a function of tim…

A study of the influence of ionic liquids properties on the Kemp elimination reaction

The morpholino-induced elimination of 5-nitrobenzisoxazole into the relevant 2-cyano-4-nitrophenolate has been used as a sample reaction in order to investigate molecular properties of some room temperature ionic liquids. The kinetic study was carried out at 298 K by means of spectrophotometric measurements. Ionic liquids, which differ in both their cation and anion properties, were used as solvent systems. In particular, aliphatic (pyrrolidinium, piperidinium, and ammonium) and aromatic (imidazolium and pyridinium) ionic liquids were used. For aromatic cations, imidazolium ions having different hydrogen-bond donor ability or a different alkyl-chain length were taken into account. The anion…

A joint action of deep eutectic solvents and ultrasound to promote Diels−Alder reaction in a sustainable way

The need to reduce environmental impact of chemical processes has induced a surge of attention in the choice of solvent and methodologies to carry them out. In this context, we studied the Diels−Alder reaction using N-ethylmaleimide as dienophile and changing the nature of the diene in deep eutectic solvents (DES) under both conventional heating and ultrasonic activation. DES obtained by the combination of different hydrogen bond acceptors and donors allowed assessing the role played by solvent nature. DES proved suitable solvent media for the target reaction, allowing higher yields and faster reactions compared to conventional organic solvents. The trend of yields, both in silent and under…

Improvement of oxidation resistance of polymer-based nanocomposites through sonication of carbonaceous nanoparticles

Abstract The work aim is focused on two different aspects: first, the investigation of the effect of extended ultra-sound-assisted treatment (us) of carbonaceous nanoparticles, such as carbon nanotubes (CNTs) and carbon black (CB), on their radical scavenging activity, and second, the investigation of the oxidative resistance of polymer-based nanocomposites, containing us-treated CNTs and CB. Particularly, the CNTs and CB have been subjected to us sonication for different time intervals and the performed analysis reveals that both kinds of nanoparticles show decreased average hydrodynamic diameters and large content of surface defects. Really, the increased content of CNTs and CB defects, a…

Carbohydrate-supramolecular gels : adsorbents for chromium(VI) removal from wastewater.

Abstract Hypothesis To overcome the contamination of water by heavy metals the adsorption of the pollutant on gel phases is an attractive solution since gels are inexpensive, potentially highly efficient and form a distinct phase while allowing diffusion of the contaminated water throughout the material. This work tests the chromium(VI) adsorbent capacity of new supramolecular gels for Chromium(VI) removal from wastewater. Experiments First hydrophobic imidazolium salts of carbohydrate anions were synthesised as new gelators. Subsequently, they were dissolved in a solvent by heating and, after cooling overnight, to give the formation of supramolecular gels. The properties of the resulting g…

End-of-life and waste management of disposable beverage cups.

Different human activities have caused and currently cause catastrophic environmental phenomena, and unfortunately, a significant negative contribution to these catastrophic phenomena can be attributed to uncontrolled plastic production, use and release everywhere. On the other hand, the plastics offer numerous comforts and advantages, and for this reason, the modern life is unthinkable without plastic. Currently, numerous scientific papers and large audience advertisings, related to the production and use of polymers made by natural sources, i.e. bio-based polymers, as a valid alternative to the petroleum-based counterparts, have been published. Therefore, for production of daily disposabl…

Non-stoichiometric dicationic organic salts form supramolecular gels

Studio delle proprietà di ionogel formati da sali organici dicationici

Sweet Ionic Liquid based Materials for Environmental Applications

On the characterization of some [bmim][X]/co-solvent binary mixtures: a multidisciplinary approach by using kinetic, spectrophotometric and conductometric investigations

Abstract In order to study the intrinsic characteristics and to evaluate the structural variations determined by the addition of a co-solvent to 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF 4 ]) we examined the behaviour of some probes in [bmim][BF 4 ]/co-solvent binary mixtures. The rate constants of the piperidino-catalyzed rearrangement of the Z -phenylhydrazone of the 3-benzoyl-5-phenyl-1,2,4-oxadiazole into the relevant 4-benzoylamino-2,5-diphenyl-1,2,3-triazole as well as the spectrometric properties of pyrene and Nile Red were evaluated. With the same purpose also 1 H NMR and conductivity measurements were carried out. By comparison the behaviour of 1-butyl-3-methylimidaz…

Ionic liquids binary mixtures and zeolites: a combination to promote carbohydrates conversion into 5-hydroxymethylfurfural

The Gelling Ability of Some Diimidazolium Salts: Effect of Isomeric Substitution of the Cation and Anion

The gelling ability of some geminal imidazolium salts was investigated both in organic solvents and in water solution. Organic salts differing either in the cation or anion structure were taken into account. In particular, the effects on the gel-phase formation of isomeric substitution on the cation or anion as well as of the use of mono- or dianions were evaluated. As far as the cation structure is concerned, isomeric cations, such as 3,3′-di-n-octyl-1,1′-(1,4-phenylenedimethylene)diimidazolium and 3,3′-di-n-octyl-1,1′-(1,3-phenylenedimethylene)diimidazolium, were used. On the other hand, in addition to the bromide anion, isomeric dianions, such as the 1,5- and 2,6-naphthalenedisulfonate a…

Catalysis in Supramolecular Systems: the Case of Gel Phases

Supramolecular gels are a fascinating class of materials, originated by the self-assembly of low molecular weight molecules. Underpinned by non-covalent interactions, they find application in a diverse range of fields. Among these, supramolecular gels can be considered as organized, non-conventional reaction media, able to influence reactivity in a radically different way, compared with what happens in solution. This short review will focus on this aspect, covering literature from 2010 onwards, addressing the application of supramolecular gels as reaction media. In particular, in the first section we explore organocatalytic reactions in gel phase, with wide synthetic relevance, such as aldo…

On the use of multi-parameter free energy relationships: the rearrangement of (Z)-arylhydrazones of 5-amino-3-benzoyl-1,2,4-oxadiazole into (2-aryl-5-phenyl-2H-1,2,3-tryazol-4-yl)ureas

Abstract By using a multi-parameter approach (a combination of Hammett/Ingold-Yukawa-Tsuno/Fujita-Nishioka free energy relationships) the mononuclear rearrangements of heterocycles (MRH) rates for five new ortho-substituted and ten new di-, tri-, or tetra-substituted (Z)-arylhydrazones of 5-amino-3-benzoyl-1,2,4-oxadiazole into the relevant (2-aryl-5-phenyl-2H-1,2,3-triazol-4-yl)ureas (in dioxane/water and in a large range of pS+ values) have been related to the electronic and proximity effects exerted by the present substituents, also considering previous results on some mono meta- and para-substituted (Z)-arylhydrazones. In every case, excellent correlation coefficients have been calculat…

Ionic liquid binary mixtures: How different factors contribute to determine their effect on the reactivity

We studied how mixing ionic liquids affected the rate of the Diels Alder reaction between 9-anthracenemethanol and N-ethylmaleimide. The mixtures considered spanned the whole compositional range and differed for the anion or the cation. These comprised mixtures of the ionic liquid 1-benzyl-3-butyl-imidazolium bis-(trifluoromethanesulfonyl)imide ([Bzbim][NTf2]) with 1-(2,3,4,5,6-pentafluorophenyl)-3-butyl-imidazolium bis-(trifluoromethanesulfonyl)imide ([Bz(F5)bim][NTf2]) or 1-benzyl-3-butyl-imidazolium tetrafluoroborate ([Bzbim][BF4]). Moreover we studied the reaction in a set of mixtures containing an aliphatic and an aromatic cation, namely [Bzbim+] and N-butyltriethylammonium ([bEt3N+]) …

Evidences of the organising ability of ionic liquids on the rate of the elimination reaction.

Aggregation processes of perylene bisimide diimidazolium salts

The supramolecular aggregation of three diimidazolium- functionalized perylene bisimides, differing in the alkyl chain length was investigated. These salts form aggregates in solvents like chloroform, dichloromethane, and glycerol. Solvent-, concentration-, and temperature-dependent spectroscopic studies were carried out, evidencing the occurrence of an isodesmic, enthalpy-driven aggregation process, underpinned by p–p stacking and hydrogen bonding. Moreover, dynamic light scattering (DLS) measurements and SEM images revealed that these salts aggregate in chloroform into elongated structures.

Supported ionic liquids. New recyclable materials for the L-proline-catalyzed aldol reaction

New materials for L-proline recycling have been developed. These materials have been applied to the L-proline-catalyzed aldol reaction between acetone and several aldehydes. The L-proline has been supported on the surface of modified silica gels with a monolayer of covalently attached ionic liquid with or without additional adsorbed ionic liquid. Good yields and ee values, comparable with those obtained under homogeneous conditions, have been obtained especially with imidazolinium-modified and 4-methylpyridinium-modified silica gels. Moreover, these materials have been easily recovered by simple filtration and studies about their reuse have been carried out. These studies showed that these …

A multivariate insight into ionic liquids toxicities

A multivariate insight into Ionic Liquids' (ILs) toxicity, a broad term highly dependent on the biological systems adopted as “sensors”, addressed four main groups of toxicities: aquatic toxicity, toxicity towards fungi and bacteria, cytotoxicity towards IPC-81 rat cell lines and acetylcholinesterase enzyme inhibition. This approach, summarizing toxicity information available from a huge amount of scattered literature data, allowed derivation of aquatic toxicity scores for 104 ILs and bacteria and fungi toxicity scores for 87 ILs as well as identification of a correlation between aquatic ecotoxicity and the response of IPC-81 rat cell lines. Further evidence on the effects of cation structu…

Solution and thermal behaviour of novel dicationic imidazolium ionic liquids

A new class of functionalised dicationic ionic liquids, containing a central cationic unit capped by a basic functionality (imidazole), has been synthesised. These salts have been characterised in isotropic solution using proton and 2D-NMR spectroscopy, and their thermal stability has been studied by DSC and TGA. All these novel salts contain the 1-(1-imidazolylmethyl)-3,5-di{1-(3'-octylimidazolylmethyl)}-benzene cation as a defining structural motif. Salts of both singly and doubly charged anions were prepared and, in particular, the selected monoanions (Br(-), [BF4](-), or [NTf2](-)) differ in size, shape and hydrogen-bonding ability, whereas the dianions differ in the nature of the space…

Geminal ionic liquids: a combined approach to investigate their three-dimensional organisation.

Different investigations, such as 1D and 2D NMR spectroscopy, resonance light scattering spectroscopy and molecular dynamics simulations, have been jointly used to achieve a deeper understanding of the degree of structural order in two geminal ionic liquids. In particular, 3,3'-di-n-butyl-1,1'-(1,3-phenylenedimethylene)diimidazolium and 3,3'-di-n-butyl-1,1'-(1,4-phenylenedimethylene)diimidazolium bis[bis(trifluoromethanesulfonyl)imide] have been studied. These geminal ionic liquids were chosen because of the presence of both a rigid phenylenedimethylene link between two imidazolium rings, which should give a high degree of order to the solvent system, and the different shapes of the two cat…

Self-Sustaining Supramolecular Ionic Liquid Gels for Dye Adsorption

Water contamination is one of the main problems of modern society, and scientific research is continuously involved in identifying solutions able to preserve this valuable source. In this context, we characterized novel ionogels formed by organic salts with different anions. In particular, they show self-strengthening behavior, a quite unusual property for supramolecular gels, and they also exhibit a good load-bearing capacity. These ionogels are able to remove cationic dyes from wastewater. Thanks to their properties, they can be used in different apparatuses like dialysis membranes and as loading in adsorption columns. In the latter case over 95% removal is achieved in less than 10 min. I…

Ionic liquids: “normal” solvents or nanostructured fluids?

Ionic liquids (ILs) are a class of non-conventional solvents, which, for almost two decades, have continued to generate burgeoning interest in different fields of present-day chemical research with few similar precedents. Among the various aspects related to ILs, a topic worthy of in-depth analysis is their influence on organic reactivity and reaction rates. In light of this, the present short review aims to provide an overview of the literature from 2010 to the present day that addresses this issue. In particular, we herein present two main different viewpoints by which the solvent effect of ILs is explained: the first is mainly based on considering the bulk polarity of ILs and linear solv…

Studio cinetico della trasposizione di Z-fenilidrazoni polisostituiti del 3-benzoil-5-fenil-1,2,4-ossadiazolo nei corrispondenti 2-aril-5-fenil-1,2,3-triazoli in H2O/Diossano

Study of aromatic nucleophilic substitution with amines on nitrothiophenes in room-temperature ionic liquids: are the different effects on the behavior of para-like and ortho-like isomers on going from conventional solvents to room-temperature ionic liquids related to solvation effects?

The kinetics of the nucleophilic aromatic substitution of some 2-L-5-nitrothiophenes (para-like isomers) with three different amines (pyrrolidine, piperidine, and morpholine) were studied in three room-temperature ionic liquids ([bmim][BF4], [bmim][PF6], and [bm(2)im][BF4], where bmim = 1-butyl-3-methylimidazolium and bm(2)im = 1-butyl-2,3-dimethylimidazolium). To calculate thermodynamic parameters, a useful instrument to gain information concerning reagent-solvent interactions, the reaction was carried out over the temperature range 293-313 K. The reaction occurs faster in ionic liquids than in conventional solvents (methanol, benzene), a dependence of rate constants on amine concentration…

A preliminary study on anion binding ability of geminal diimidazolium salts

Trasposizioni eterocicliche mononucleari. Reattività di Z-arilidrazoni del 5-ammino-3-benzoil-1,2,4-ossadiazolo in D/W: effetto dei sostituenti

Effect of ionic liquids in acid-promoted heterocyclic rearrangement reaction

Ionic Liquids: as the different structural order degree can affect the outcome of a reaction

Solvatochromic behaviour of new donor–acceptor oligothiophenes

Oligothiophene derivatives play a central role in the formulation of materials used in devices in the field of organic electronics. In this work, we report the results of the study of UV-vis absorption and fluorescence spectra, in several solvents, of a series of oligothiophenes recently synthesized in our laboratory. The studied oligothiophenes present different structures due to several factors: the donor– acceptor (D–A) or acceptor–donor–acceptor (A–D–A) architecture, the number of thiophene rings in the backbone (ranging from three to eight), the number and position of solubilizing octyl chains in the backbone, and the type of acceptor moieties (from Knoevenagel condensation either with…

Antimicrobial and antioxidant supramolecular ionic liquid gels from biopolymer mixtures

In this work, we describe the preparation and characterization of supramolecular ionic liquid gels based on binary mixtures of biopolymers, comprising chitosan, chitin, cellulose and lignin. The gels were obtained in ionic liquids differing in the cation or the anion, with no need for a cross-linking agent or acid treatment. The materials obtained were characterized for the minimum gelation concentration, porosity, swelling and rheological properties, finding a prominent influence of the nature of the ionic liquid anion. Then, we investigated the ability of the gels to scavenge free radicals, finding that the gels exhibit a higher antioxidant ability than their individual components. Moreov…

Acidic imidazolium salts: catalysts for biomass transformation

Spectrophotometric determinations of binding constants between cyclodextrins and aromatic nitrogen substrates at various pH values

The inclusion capacity of native β-cyclodextrin (1) and mono-(6-amino-6-deoxy)-β-cyclodextrin (2) versus aromatic compounds having a nitro or an amino group or both has been investigated at three different pH values. Molecular interactions in inclusion complexes have also been investigated by means of molecular mechanics (MM2/QD) models. Electrostatic and van der Waals interactions and the formation of a hydrogen bond between the donor amino group and the oxygen atom of the secondary hydroxyl group seem to be the more important contributions in determining complex stability. The inclusion capacity of two different cyclodextrins versus aromatic compounds has been investigated at three differ…

DICATIONIC IMIDAZOLIUM SALTS: TUNABLE ANTIMICROBIAL AND ANTITUMORAL CHEMIOTHERAPEUTIC LEADS

The chemical synthesis of novel chemotherapeutical leads is evolving thanks to possibility to design molecules with desired physical-chemical and, thus, biological properties. The imidazolium salts, recently proven effective to inhibit bacterial and/or cancer cell growth, posses an amphiphilic nature that is conferred by the imidazolium cation having a polar head generally coupled with aliphatic side chains. Thus, biological properties of imidazolium salts can be tuned through modifications involving the cation structure and/or the anion nature. By covalently linking two imidazolium rings, di-imidazolium salts were obtainedobtain differing in: i) kind of anions; ii) geometric isomerization …

Kemp elimination: a probe reaction to study ionic liquids properties.

The amino induced elimination of benzisoxazole into the relevant o-cyanophenolate ion (Kemp elimination) has been studied in [bmim][BF 4] solution at 298 K. To have information about the interactions between reactants and ionic liquid, the reaction has been carried out at different temperatures (293-313 K). Several primary, secondary, and tertiary amines have been used to study the effect of amine structure on the reaction rate. The collected data show that the amine structure seems to have a crucial role in determining the reaction rate. Furthermore, as different cation or anion structures of an ionic liquid can significantly affect its properties, the title reaction has been performed in …

As the change in ternary agent structure influence the chiral recognition ability of pyrene/heptakis-(6-amino)-(6-deoxy)-b-cyclodextrin

Ionic liquid binary mixtures: Promising reaction media for carbohydrate conversion into 5-hydroxymethylfurfural

Abstract The conversion of carbohydrates into 5-hydroxymethylfurfural (5-HMF) has been studied in binary mixtures of ionic liquids (ILs), using strongly acidic resin Amberlyst 15 as the catalyst. In particular, both mono- and disaccharides, such as fructose, glucose and sucrose have been investigated. Considering the favorable effect exerted by chloride-based ionic liquids in the dissolution of carbohydrates, we used binary mixtures of 1-butyl-3-methylimidazolium chloride ([bmim][Cl]) with [bmim + ] based ionic liquids differing in size, shape and coordination ability of the anion ([bmim][BF 4 ], [bmim][N(CF 3 SO 2 ) 2 ], [bmim][N(CN) 2 ], [bmim][SbF 6 ] and [bmim][CF 3 SO 3 ]). Carbohydrat…

The anion impact on the self-assembly of naphthalene diimide diimidazolium salts

Naphthalene diimide diimidazolium salts differing in the anion nature were synthesized and their properties as well as their self-assembly behaviour were investigated. In particular, we took into consideration the N,N′-bis-(1-octyl-3-propylimidazolium)-naphthalene diimide cations and anions differing in size, shape and coordination abilities like [I−], [BF4−] and [NTf2−]. After determination of thermal behaviour, using differential scanning calorimetry and thermal gravimetric analysis, the electrochemical stability and redox properties were assessed using cyclic voltammetry. The self-assembly behaviour of the salts was investigated using concentration and temperature-dependent spectroscopic…

Self-assembly process of diimidazolium salts: the effect of the alkyl chain length and isomeric substitution

Cyclodextrin-[60]fullerene conjugates: Synthesis, characterization and electrochemical behavior

Chiral recognition of protected amino acids by means of fluorescent binary complex pyrene/heptakis-(6-amino)-(6-deoxy)-β-cyclodextrin

The ability of the binary complex pyrene (Py)/heptakis-(6-amino)-(6-deoxy)-β-cyclodextrin (am-β-CD) to act as a chiral selector was tested at two pH values (8.0 and 9.0). Phenylalanine (Phe), methionine (Met) and histidine (His) were used as chiral model molecules. The stability of ternary complexes Py/am-β-CD/amino acid was determined by means of spectrofluorimetric measurements. The data collected showed an increase in stability going from the binary to ternary complex and above all the possibility to use the binary complex as a chiral selector. Finally, data collected at two pH values showed that the binary complex is a better chiral selector when charged rather than in its neutral form.

Self-assembly of a fluorescent diimidazolium naphthalene diimide salt: the effect of increasing alkyl chain length

Isomerization and rearrangement of (E)- and (Z)-phenylhydrazones of 3-benzoyl-5-phenyl-1,2,4-oxadiazole: evidence for a “new” type of acid-catalysis by copper(II) salts in mononuclear rearrangement of heterocycles

A kinetic investigation in methanol of the title reaction has evidenced the occurrence of two processes: the 1-E1-Z isomerization and the rearrangement of the (Z)-isomer into the relevant 4-benzoylamino-2,5-diphenyl-1,2,3-triazole (1-Z  T). The latter reaction is in line with the ability of the (Z)-phenylhydrazones of 3-benzoyl-1,2,4-oxadiazoles to undergo the so called mononuclear rearrangement of heterocycles (MRH). The occurrence of both the examined reactions is dependent on a Lewis-acid-catalysis. The obtained results have shown the possibility of a ‘new’ type of acid-catalysis (bifunctional catalysis by Lewis salts) in the MRH. This catalysis operates through a completely different me…

Alkyl chain length effect on the self assembly of diimidazolium naphthalene diimide salts

The effect of ionic liquids on the rate of an intramolecular nucleophilic substitution: the study of a monocyclic rearrangement of heterocycles

On the Dichotomic Behavior of the Z-2,4-Dinitrophenylhydrazone of 5-Amino-3-benzoyl-1,2,4-oxadiazole with Acids in Toluene and in Dioxane/Water:  Rearrangement versus Hydrolysis

The mononuclear rearrangement (MRH) of the Z-2,4-dinitrophenylhydrazone (4a) and of the Z-phenylhydrazone (4b) of 5-amino-3-benzoyl-1,2,4-oxadiazole into the relevant triazoles 5a and 5b in toluene has been quantitatively investigated in the presence of trichloroacetic acid (TCA) and of piperidine at 313.1 K. While the behavior in the presence of piperidine recalls the one previously evidenced for some Z-hydrazones of 3-benzoyl-5-phenyl-1,2,4-oxadiazole, the study of the reactivity in the presence of TCA has most interestingly evidenced a general-acid-catalyzed rearrangement for “both” 4a and 4b. Thus, 4a offers the first example of a solvent-dependent dichotomic behavior in MRH processes o…

Environmentally Friendly Eutectogels Comprising l-amino Acids and Deep Eutectic Solvents: Efficient Materials for Wastewater Treatment.

Current concerns for sustainability and the environment make low-impact materials desirable for environmental remediation and, in particular wastewater treatment. We obtained supramolecular gels of l-amino acids in the deep eutectic solvent formed by choline chloride and phenylacetic acid. After gel characterization, and investigating gel-sol transition temperatures, gelation kinetics, rheological properties, and morphology, the gels were applied as sorbents to remove cationic dyes from aqueous solutions. The effects of the pH, dye nature, volume, and concentration of wastewater were analyzed, and the best result was obtained with a l-phenylalanine-based eutectogel. It can be reused for at …

Two components hydrogels formed by host-guest interactions

The ionic liquid effect on the Boulton-Katritzky reaction: a comparison between substrates of different structure

The mononuclear rearrangement of heterocycles, also called Boulton–Katritzky reaction, was studied in ionic liquid solution using N-(5-phenyl-1,2,4-oxadiazol-3-yl)-N′-(4-nitrophenyl)-formamidine as substrate. The investigation was carried out using piperidine as basic catalyst and several ionic liquids differing in both cation and anion structure. Kinetic data collected were compared with the ones previously reported using (Z)-phenylhydrazone of 3-benzoyl-5-phenyl-1,2,4-oxadiazole to have information about the effect due to the different structure of the alkyl chain borne on the substrate. Furthermore, data were analysed on the grounds of polarity, Kamlet–Taft solvent parameters, but taking…

Binding properties of polyaminocyclodextrin materials towards polyanions and p-nitroaniline derivatives

A kinetic study of the basic hydrolysis of 2-phenylethyl nitrite in the presence of borate buffer and β-cyclodextrin

The kinetics of the hydrolysis of 2-phenylethyl nitrite have been studied in basic aqueous solutions (borate buffer) in the absence and presence of β-cyclodextrin. The observed kinetic trends show that the hydrolysis reaction consists of at least three subsequent processes. The first is a fast acid-base reaction between the boron atom of boric acid and oxygen atom of the alkyl nitrite. The second one should be the nucleophilic attack of hydroxyl ion on the alkyl nitrite. The last process could be referred to as a combination of transfer of hydrogen acid to a water molecule followed by ruptures of nitrogen-oxygen and boron-oxygen bonds. The effect of β- cyclodextrin on each process is also d…

Diimidazolium-based supramolecular ionogels for dye removal from wastewaters

Supramolecular complexes formed by dimethoxypillar[5]arenes and imidazolium salts: A joint experimental and computational investigation

To gain more insights into the factors acting on the stability of complexes formed by pillar[5]arenes, we investigated the interaction of dimethoxypillar[5]arene with some 1-(n-alkyl)-3-(9-anthracenylmethyl)-imidazolium based organic salts. In particular, we used salts differing in not only the anion nature ([Cl−], [BF4−], [NTf2−] and [SbF6−]) and alkyl chain length (butyl, octyl and dodecylimidazolium derivatives), but also the presence of a hydrogenated or fluorinated tail (octyl and perfluorooctylimidazolium derivatives). Host–guest systems were analysed in solution, solid state and gas phase, using a combined approach of different techniques like fluorescence, 1H NMR, ESI-MS, DSC and DF…

Supramolecular Eutecto Gels: Fully Natural Soft Materials

The obtainment of materials featured by high environmental compatibility is one of the main goals of modern research. On this subject, we herein report the first example of supramolecular gel in deep eutectic solvents. In particular, we prepared gels of the L-amino acids isoleucine and tryptophan in choline chloride/phenylacetic acid 1:2. All gel components are readily available and nontoxic. Gels have been fully characterized by standard gelation tests, rheology, X-ray diffraction, morphology and gelation kinetics. Data collected show that gels properties depend on the gelator nature. In particular, gel phases exhibit strong colloidal forces and, this high mechanical resistance, together w…

The ultrasounds-ionic liquids synergy on the copper catalyzed azide-alkyne cycloaddition between phenyl acetylene and 4-azidoquinoline

Abstract The effect of ultrasound irradiation on the copper catalyzed azide–alkyne cycloaddition between phenylacetylene and 4-azidoquinoline has been studied in solution of different ionic liquids. In particular, we used ionic liquids featuring both aliphatic and aromatic mono- and dications, as well as anions differing in size, symmetry and coordination ability. We also examined the influence of the ionic liquids structural features on the reaction outcomes, finding that under magnetic stirring reactivity is favorably affected by the solvent structural organization, while under sonochemical conditions an opposite trend was observed. In all cases examined, sonochemical activation leads to …

Polystyrene-supported proline as recyclable catalyst in the Baylis–Hillman reaction of arylaldehydes and methyl or ethyl vinyl ketone

Abstract Polystyrene-supported proline has been used as co-organocatalyst (10 mol%) with imidazole (10 mol%) in the Baylis–Hillman reaction between methyl or ethyl vinyl ketone and arylaldehydes. Recycling studies showed that the proline resin can be used up to five cycles with high isolated yields. This study represents the first example of supported proline as heterogeneous catalyst in the above reaction and broaden the scope of this catalytic material.

Binding properties of mono-6-amino-beta-cyclodextrin towards p-nitroaniline derivatives: a polarimetric study

The influence of steric effects on the strength of some organic acids in toluene and water

Aryl azides formation under mild conditions: a kinetic study in some ionic liquid solutions.

The kinetics of nucleophilic aromatic substitution of three nitrothiophene derivatives in different [1-butyl-3-methylimidazolium][N(3)]/ionic liquid binary mixtures was studied spectrophotometrically at 298 K. Ionic liquids differing for cation structure (imidazolium or pyrrolidinium) and for size, shape, and coordination ability of the anion ([BF(4)(-)], [PF(6)(-)], [SbF(6)(-)], and [NTf(2)(-)]) were used. Furthermore, in order to have a comparison with conventional organic solvents, the target reaction was also carried out in DMF solution at increasing concentration of NaN(3) or [bmim][N(3)]. Data collected show that the reaction occurs faster in DMF than in ionic liquid solution. Further…

Insights into the anion effect on the self assembly of perylene bisimide diimidazolium salts

Abstract We studied how changing the anion affects the self-assembly of three diimidazolium salts bearing a perylene bisimide spacer. In particular we used [BF 4 − ] and [NTf 2 − ] based salts together with a mixed salt bearing both [I − ] and [BF 4 − ] anions. Thermal as well as concentration and temperature dependent spectroscopic investigations revealed that changing the anion impacts on solid state and solution aggregation, leading to articulate thermotropic behaviors and contrasting solvent effects, respectively. We also studied the electrochemical behavior of the salts to verify if changing the anion alters the redox properties of the salts. Finally, different anions also lead to very…

Bio-based chitosan and cellulose ionic liquid gels: polymeric soft materials for the desulfurization of fuel

Desulfurization of fuel that avoids the introduction in the atmosphere of toxic sulfur volatile compounds, usually formed during combustion, is a viable strategy to reduce pollution. To find new efficient and eco-sustainable adsorbent materials, bio-based polymers such as chitosan (CS), cellulose (CE) and cellulose acetate (CEOAc) were dissolved in ionic liquids (ILs) to form ionic liquid gels (ILGs). Gelling and swelling ability, porosity, morphology, rheology and mechanical response were studied as a function of the polymer and ionic liquid (IL) used. The best performing gels were tested for fuel desulfurization using a fuel mimicking solution of thiophene (T), benzothiophene (BT) and dib…

Ionic Liquid Binary Mixtures, Zeolites, and Ultrasound Irradiation: A Combination to Promote Carbohydrate Conversion into 5-Hydroxymethylfurfural

The efficient conversion of biomass into value-added compounds under mild and safer conditions is a cornerstone of present research efforts to meet the needs of the chemical industry with sustainable development. In this work, we studied the dehydration of fructose, glucose, and sucrose into 5-hydroxymethylfurfural (5-HMF), catalyzed by HY zeolite, in three ionic liquid mixtures differing for the cation, aromatic, or aliphatic. We investigated the effect of several operational parameters such as temperature, catalyst loading, zeolite counterion, solvent mixture, and added chloride. In the optimal experimental conditions, we obtained good conversions to 5-HMF especially for fructose and sucr…

Determination of basic strenght of aliphatic amines through ion pair formation in some ionic liquid solutions

To have an evaluation of the basic strength of aliphatic amines in ionic liquid solution, the stability constants relevant to the formation of amine/p-nitrophenol ion pairs were determined in different ionic liquids at 298 K. In particular, aliphatic (pyrrolidinium) and aromatic (imidazolium) ionic liquids were used. Imidazolium ions, bmim(+) and bm(2)im(+), having different hydrogen bond donor abilities were taken into account. Anions were chosen ([BF(4)(-)], [PF(6)(-)], and [NTf(2)(-)]; where NTf(2) = bis(trifluoromethansulfonyl)imide) showing different shape, size, and coordination ability. Several primary, secondary (cyclic or not), and tertiary amines were used to study the effect of a…

Spectrophotometric determination of binding constants between some aminocyclodextrins and nitrobenzene derivatives at various pH values

Abstract The inclusion capacity of three modified cyclodextrins—namely mono-(6- N , N -dimethylamino-6-deoxy)- ( 3 ), mono-6-(2-aminoethyl)-amino-6-deoxy- ( 4 ) and mono-6-(2- N , N -dimethylaminoethyl)-amino-6-deoxy- ( 5 ) β-cyclodextrin, with six para -substituted nitrobenzenes ( A – F ) has been investigated at three different pH values. Molecular interactions in inclusion complexes have also been investigated by means of molecular mechanics (MM2/QD) models. The desolvation of the cyclodextrin is the most important factor in determining the binding ability of the various hosts. However, for a given host, electrostatic and van der Waals interactions and the formation of a hydrogen bond be…

Fully ionic metallogels from dicationic diimidazolium salts

Breakthrough in the α-Perchlorination of Acyl Chlorides

The preparation of -perchloroacyl chlorides, from reaction of the corresponding unfunctionalized acyl halides with chlorine, was efficiently achieved under base-catalysis, using a tetraalkylammonium chloride as catalyst. The process is solvent-free and the procedure is easy, inexpensive, and suitable for scale-up.

Binary complexes heptakis-(6-amino)-(6-deoxy)-beta-cyclodextrin/fluorophore: structural investigation and chiral recognition

Inside Back Cover: Aggregation Processes of Perylene Bisimide Diimidazolium Salts (Chem. Eur. J. 42/2015)

Hybrid supramolecular gels of Fmoc-F/halloysite nanotubes: Systems for sustained release of camptothecin

Supramolecular gel hybrids obtained by self-assembly of Fmoc-L-phenylalanine (Fmoc-F) in the presence of functionalized halloysite nanotubes (f-HNT) were obtained in biocompatible solvents and employed as carriers for the delivery of camptothecin (CPT) molecules. The synthesis of the new f-HNT material as well as its characterization are described. The properties of the hybrid hydrogels and organogels were analyzed by several techniques. The presence of small amounts of f-HNT allows good dispersion of the tubes and the subsequent formation of homogeneous gels. The experimental results show that f-HNT functions only as an additive in the hybrid gels and does not demonstrate gelator behavior.…

Self-assembly of fluorescent diimidazolium salts: tailor properties of the aggregates changing alkyl chain features

Searching for new fluorescent organic salts to be used in biomedical and electrochemical field, we conjugated properties of imidazolium salts with the ones of naphthalene diimide core and we obtained some N,N′-bis-(1-alkyl-3-propylimidazolium)naphthalene diimide diiodides. We took into account alkyl chains going from hexyl to dodecyl, as well as hydrogenated and fluorinated alkyl tails. After determination of their thermal behaviour by differential scanning calorimetry, concentration-, and temperature-dependent spectroscopic studies (UV-vis and fluorescence) were performed evidencing the occurrence of isodesmic and enthalpy-driven self-assembly processes. Properties of aggregates were also …

Dicationic organic salts: gelators for ionic liquids

Diimidazolium and dipyrrolidinium organic salts were tested for their ability to gel both organic solvents and ionic liquids. Organic salts containing 1-(1-imidazolylmethyl)-3,5-di-(3'-octylimidazolylmethyl)-benzene and 1-(N-pyrrolidylmethyl)-3,5-di-(N,N-octylpyrrolidylmethyl)-benzene cations were used. In addition to the simple bromide anion, also dianions having a naphthalene core such as 1,5- and 2,6-naphthalenedisulfonate and 2,6-naphthalenedicarboxylate were taken into account. Gelation tests demonstrated that organic salts used were able to harden ionic liquids. The materials obtained were investigated for their thermal stability and also for electric conductivity properties using mic…

Ionic Liquid Gels: Supramolecular Reaction Media for the Alcoholysis of Anhydrides.

The search of new enantioselective catalysts, able to promote synthetically useful organic reactions with high levels of asymmetric induction, should be associated with the attention to the suitable reaction medium able to achieve the best efficiency in chemical processes. We have investigated the enantioselective desymmetrization of cyclic meso-anhydrides in nonconventional reaction media such as ionic liquids and supramolecular gels. With this aim, we examined several variables in the reacting system: the nature of ionic liquid used as the reaction medium, the gelation solvent, the structure of the anhydrides, the structure of alcohols, the chiral catalysts, and the reaction conditions, i…

A deep insight into the mechanism of the acid-catalyzed rearrangement of the Z-phenylhydrazone of 5-amino-3-benzoyl-1,2,4-oxadiazole in a non-polar solvent

The conversion of the Z-phenylhydrazone of 5-amino-3-benzoyl-1,2,4-oxadiazole (1a) into the relevant 1,2,3-triazole (2a) has been quantitatively studied in toluene in the presence of several halogenoacetic acids (HAAs, 3a–h). Again, the occurrence of two reaction pathways has been pointed out: they require one or two moles of acid, respectively, thus repeating the situation previously observed in the presence of trichloroacetic acid. The observed rate constant ratios (kIII/kII) are only slightly affected by the nature of the acid used. To gain a deeper insight into the action of the acids used we have measured the association constants of the HAAs (3a–h) with 4-nitroaniline (4) in toluene. …

Dicationic Organic Salts: our recent journey in their properties and applications

Anti-/Pro-Oxidant Behavior of Naturally Occurring Molecules in Polymers and Biopolymers: A Brief Review

Polymers and biopolymers are continuously subjected to the action of different stress factors, such as oxygen, heat, UV light, mechanical stress, humidity, etc., during their processing and service life, undergoing overall oxidative degradation, that causes performance and property deterioration. To improve the resistance at high temperatures and long-term weatherability of the polymers and biopolymers, usually, during their manufacturing, synthetic antioxidants and UV-light stabilizers are added. In the past decade, several concerns related to the impact of the synthetic stabilizers have emerged, and to reduce their negative effect on human health and the environment, their replacement wit…

Effetto della struttura dei liquidi ionici sulla reazione di trasposizione eterociclica mononucleare: un approccio usando i parametri termodinamici

Lipase-catalyzed resolution of β-hydroxy selenides

Abstract Eleven β-hydroxy selenides were kinetically resolved using an immobilized lipase (Amano PS-C II) in toluene in the presence of vinyl acetate at 30 °C. This approach provided, in several cases, both enantiomers in high enantiomeric excess. The role of the size of substituents and the behaviour of cyclic β-hydroxy selenides is also discussed. Enantiopure β-hydroxy selenides are useful building blocks. As an application of this chemistry, enantiopure (1 S ,2 R )-indene oxide was obtained in one step from the proper enantiopure β-hydroxy selenide.

COLLARD GREEN (BRASSICA OLERACEA VAR. ACEPHALA) CULTIVATION IN SICILY

Collard greens (Brassica oleracea var. acephala) are a group of plants cultivated for its thick, slightly bitter, edible leaves. As other Brassicaceae, have a good nutritional value as they are a good sources of vitamin C and soluble fiber, and contain various compounds with potent anticancer properties. In order to enhance collard cultivation in Sicily, different planting dates were tested. The research was carried out during 2009-2010 in the experimental field of SAgA Department – University of Palermo. Plants of a Sicilian local cultivar, with high vigor, good emission of side shoots, large and moderately curly leaves and long and strong petiole, were planted in three different periods: …

How mixing ionic liquids affects a Diels-Alder reaction

Synthesis of aryl azides: A probe reaction to study the synergetic action of ultrasounds and ionic liquids

Abstract The combined effect of ultrasounds and ionic liquids was used to perform the synthesis of aryl azides by nucleophilic aromatic substitution in ionic liquid/[1-butyl-3-methylimidazolium][N 3 ] binary mixtures. The ultrasounds efficiency was analyzed as a function of the substrate and of the ionic liquid structure. In the first case, both 6π and 10π electrons aryl halides were considered. As far as the ionic liquid structure is concerned, both aromatic and aliphatic ionic liquids were taken into account. Among aromatic cations, the effects due to different ability in giving hydrogen bond or π–π interactions were considered. The use of a geminal ionic liquid having an aromatic spacer …

[bmim][F] a TSIL differently acting on aromatic nuclei

N-heterocyclic carbenes and parent cations: acidity, nucleophilicity, stability, and hydrogen bonding-Electrochemical Study and ab initio calculations

N-Heterocyclic carbenes (NHCs) are widely used as organocatalysts. Their reactivity (and instability) is related to their basicity and nucleophilicity, which, in turn, are linked to their scaffold. NHCs can be generated by chemical deprotonation or electrochemical reduction of the parent azolium cations, NHCH+s. Cyclic voltammetry enabled the reduction potential of the NHCH+s to be determined; the reduction potential is related to the acidity of the NHCH+s and the oxidation potential of the NHCs, which is related to the nucleophilicity of the NHCs. It was thus possible to order different NHCH+s and NHCs by their acidity and nucleophilicity, respectively. A study on the stability of NHCs was…

Task-Specific Organic Salts and Ionic Liquids Binary Mixtures: A Combination to Obtain 5-Hydroxymethylfurfural From Carbohydrates

The increase in energy demand and depletion of fossil fuels are among major issues of modern society. Valorization and transformation of raw materials in products of industrial value represents a challenge. This justifies the growing interest of scientific research towards the identification of suitable media and methodologies able to pursue above goals, paying attention to matter of sustainability. On this subject, we studied sulfonic-acid functionalized diimidazolium salts as catalysts for the conversion of fructose and sucrose to 5-hydroxymethylfurfural (5-HMF) in an ionic liquid mixture. In general, using these salts allowed us to obtain 5-HMF in good yields from both substrates in mild…

L'assenza di solvatazione può giustificare l'aumento della velocità dei processi di interconversione di anello in liquidi ionici?

Azolium and acetate ions in DMF: Formation of free N-heterocyclic carbene. A voltammetric analysis

In order to reveal the possible formation of free N-heterocyclic carbene (NHC) in DMF-azolium and acetate solutions, the proton exchange equilibrium between azolium cations and CH3COO− was investigated (by cyclic voltammetry) by adding CH3COOH or tetrabutylammonium acetate to DMF solutions of imidazolium or thiazolium salts of different acidity.The voltammetric analysis confirms that the deprotonation of the azolium cation by CH3COO− (with the formation of free NHC) is significant in the case of the more acidic thiazolium cations, while it is not effective with the less acidic imidazolium ones.Accordingly, the NHC-catalyzed benzoin condensation was carried out in DMF solutions of azolium sa…

Microwave-assisted synthesis of novel cyclodextrin–cucurbituril complexes

Microwave irradiation was successfully used in order to obtain stable supramolecular aggregates between cyclodextrins and cucurbiturils, without the participation of any long-chain common ‘molecular thread’ guest. These aggregates were characterised by means of various different techniques, namely NMR, thermogravimetry, polarimetry and ESI-MS. Cross-analysis of experimental data allowed us to obtain insights on the stoichiometries of the composites and their thermal stabilities. The possible structures of the composites are briefly discussed, as well as the actual nature of their intrinsic stability.

Cathodic behaviour of dicationic imidazolium bromides: the role of the spacer

The cathodic reduction of dicationic imidazolium bromides, whose spacer is either an aliphatic chain or a xylyl group, leads to the formation of the corresponding N-heterocyclic carbenes (NHCs), which were isolated as the corresponding thiones, after reaction with elemental sulfur. The behaviour of the dications was compared with the corresponding monocations. The behaviour of dicarbenes depends on the nature of the spacer. This study evidenced that dicarbenes deriving from xylyl dications are less stable than the corresponding aliphatic ones (giving lower yields in thiones), due to a debenzylation reaction. On the other hand, the yields in thiones starting from aliphatic dications are high…

Trasposizioni eterocicliche mononucleari. Applicazione dell'equazione di Fujita-Nishioka alla reattività di Z-fenilidrazoni di- e poli-sostituiti del 3-benzoil-5-fenil-1,2,4-ossadiazolo.

Reazione di eliminazione di Kemp in liquidi ionici: uno studio cinetico

Natural Compounds as Sustainable Additives for Biopolymers

In the last few decades, the interest towards natural compounds, coming from a natural source and biodegradable, for biopolymers is always increasing because of a public request for the formulation of safe, eco-friendly, and sustainable materials. The main classes of natural compounds for biopolymers are: (i) naturally occurring fillers (nFil), such as nano-/micro- sized layered alumino-silicate: halloysite, bentonite, montmorillonite, hydroxyapatite, calcium carbonate, etc.; (ii) naturally occurring fibers (nFib), such as wood and vegetable fibers; (iii) naturally occurring antioxidant molecules (nAO), such as phenols, polyphenols, vitamins, and carotenoids. However, in this short review, …

NMR Study of the (Z)-Phenylhydrazones of 5-Alkyl- and 5-Aryl-3-benzoyl-1,2,4-oxadiazoles: Support for the Interpretation of Kinetic Results on the Rearrangement of 1,2,4-Oxadiazoles to 1,2,3-Triazoles

An analysis of the 1H, 13C, and 15N NMR substituent chemical shifts (SCSs) of the title compounds in CDCl3 solution has been carried out by using the SCSs of other classes of compounds (arenes, methyl esters or amides), Hammett substituent constants or kinetic data. The results obtained provide information concerning the ground-state electronic distribution of the compounds examined. The results relevant to the carbon and nitrogen atoms of the 1,2,4-oxadiazole ring can be considered of special interest, as the effects of the substit- Introduction For several years our research group has been involved in the use of NMR spectroscopic data (1H, 13C, 15N, and 17O) to obtain information about th…

Enantioselective recognition of alfa-amino acids by binary complexes fluorophore/cyclodextrin

Two-Component Hydrogels Formed by Cyclodextrins and Dicationic Imidazolium Salts

In the framework of our recent interest in studying the gelling behaviour of imidazolium salts, we took into account the possibility of obtaining two-component hydrogels by combining cyclodextrins and dicationic imidazolium salts. In particular, we used diimidazolium salts differing in the alkyl chain length and in the size, shape, and coordination ability of the anion, namely the 3,3′-di-n-decyl- and 3,3′-di-n-dodecyl-1,1′-(1,4- phenylenedimethylene)diimidazolium dibromide, and 3,3′-di-n-dodecyl-1, 1′-(1,4-phenylenedimethylene)diimidazolium ditetrafluoroborate and dihexafluorophosphate. As far as cyclodextrins are concerned, to gain information on the effects of different sized cyclic olig…

Studio polarimetrico degli equilibri di inclusione tra ciclodestrine native ed opportuni guest modello alifatici e aromatici

Ionic liquids/[bmim][N3] mixtures: promising media for the synthesis of aryl azides by SNAr

The nucleophilic aromatic substitution of some activated aryl or heteroaryl halides has been performed in ionic liquid solution, using the 1-butyl-3-methylimidazolium azide as a nucleophile. The reaction course was studied varying the structures of both substrates and ionic liquids. In particular, in the latter case, the reaction of 2-bromo-5-nitrothiophene was carried out in five different ionic liquids ([bmim][BF 4], [bmim][PF 6], [bmim][NTf 2], [bm 2im][NTf 2], and [bmpyrr][NTf 2]). Finally, for all the substrates considered, a comparison with data obtained in MeOH solution in the presence of NaN 3 was also performed. Data collected indicate that in some cases it is possible to obtain ar…

Miscela binaria liquido ionico/[bmim][N3]: un mezzo efficace per la sintesi di arilazidi mediante SNAr

Reattività dei fenilidrazoni E e Z del 3-benzoil-5-fenil-1,2,4-ossadiazolo in presenza di sali di Cu(II)

Study of aromatic nucleophilic substitution with amines on nitrothiophenes in RTILs: are the different effects on the behavior of para-like and orto-like isomers on going from conventional solvents to RTILs related to solvation effects?.

The kinetics of the nucleophilic aromatic substitution of some 2-L-5-nitrothiophenes (para-like isomers) with three different amines (pyrrolidine, piperidine, and morpholine) were studied in three roomtemperature ionic liquids ([bmim][BF4], [bmim][PF6], and [bm2im][BF4], where bmim ) 1-butyl-3- methylimidazolium and bm2im ) 1-butyl-2,3-dimethylimidazolium). To calculate thermodynamic parameters, a useful instrument to gain information concerning reagent-solvent interactions, the reaction was carried out over the temperature range 293-313 K. The reaction occurs faster in ionic liquids than in conventional solvents (methanol, benzene), a dependence of rate constants on amine concentration sim…

MODIFICAZIONI COVALENTI DI NANOTUBI DI ALLOSITE PER APPLICAZIONE NEL DRUG DELIVERY

Nell'ampio scenario dei nanomateriali, i sistemi nanotubolari godono di un consolidato e crescente interesse sia nell'ambito scientifico che industriale. Fra la miriade di sistemi tubolari, recentemente i nanotubi allosite (HNT) hanno attirato l’attenzione della comunità scientifica.1 Grazie alla presenza di una cavità vuota, gli HNT trovano, principalmente, applicazione come nanocontainer per il rilascio controllato di composti chimici, in particolare, farmaci. L’introduzione di modificazioni covalenti su entrambe le superfici permette di modulare le proprietà dell’allosite, aumentando così i suoi campi di applicazione. In questa comunicazione verranno presentati recenti risultati ottenuti…

Binding equilibria between beta-cyclodextrin and p-nitro-aniline derivatives: the first systematic study in mixed water-methanol solvent systems.

Abstract Complexation equilibria, in mixed water–methanol solvent media, between native β-cyclodextrin and a set of suitably selected p -nitro-aniline derivatives were studied by means of polarimetry. The effects exerted by the organic co-solvent on the conditional inclusion free energies Δ G cond 0 and the differential molar optical rotations Δ Θ were thoroughly analyzed under the perspective of the enthalpy–entropy compensation effect. Experimental data suggest an intimate participation (‘dynamic co-inclusion’) of solvent molecules in the formation and in the conformational dynamics of the host–guest inclusion complex.

Ionic liquids gels: Soft materials for environmental remediation

Abstract Hypothesis Nanostructured sorbents and, in particular, supramolecular gels are emerging as efficient materials for the removal of toxic contaminants from water, like industrial dyes. It is also known that ionic liquids can dissolve significant amounts of dyes. Consequently, supramolecular ionic liquids gels could be highly efficient sorbents for dyes removal. This would also contribute to overcome the drawbacks associated with dye removal by liquid–liquid extraction with neat ionic liquids which would require large volumes of extractant and a more difficult separation of the phases. Experiments Herein we employed novel supramolecular ionic liquid gels based on diimidazolium salts b…

The binary pyrene/heptakis-(6-amino-6-deoxy)-β-cyclodextrin complex: A suitable chiral discriminator. Spectrofluorimetric study of the effect of some α-amino acids and esters on the stability of the binary complex

The effect of some α-amino acids and their esters on the stability of the binary pyrene/heptakis-(6-amino-6-deoxy)-β-cyclodextrin (py/am-β-CD) complex has been studied by means of fluorescence spectroscopy at two pH values (8.0 and 9.0). The binary complex was generally stabilized by adding the ternary agent at pH 8.0. A more varied substrate effect is observed at pH 9.0 where am-β-CD is present in the uncharged form. The conditional constant (β2) values determined by L/D α-amino acids show that the binary complex is a suitable receptor for chiral recognition. The enantiomer selectivity values obtained, ranging from 1.2 up to 7.4, are generally higher than those reported for α-amino acids a…

Supramolecular aggregation of bis-imidazolium functionalised perylene bisimides

Electronic and Steric Effects: How Do They Work in Ionic Liquids? The Case of Benzoic Acid Dissociation

The need to have a measure of the strength of some substituted benzoic acids in ionic liquid solution led us to use the protonation equilibrium of sodium p-nitrophenolate as a probe reaction, which was studied by means of spectrophotometric titration at 298 K. In order to evaluate the importance of electronic effect of the substituents present on the aromatic ring, both electron-withdrawing and -donor substituents were taken into account. Furthermore, to have a measure of the importance of the steric effect of the substituents both para- and ortho-substituted benzoic acids were analyzed. The probe reaction was studied in two ionic liquids differing for the ability of the cation to give hydr…

Natural eutectogels: sustainable catalytic systems for C–C bond formation reactions

Natural eutecto gels were prepared combining properties of amino acids with the ones of deep eutectic solvents. Soft materials obtained were fully characterised determining the gel-sol transition temperatures and analysing mechanical and morphological features through rheological measurements and polarised optical microscopy. All eutecto gels were tested as catalytic reaction media for the enantioselective aldol reaction and, the best performing one was also used to carry out the Michael addition. In both cases, eutecto gels proved to have a great potential as sustainable reaction media, allowing to perform processes under mild conditions, obtaining excellent yields and, in some cases, also…

Polysaccharide-based supramolecular bicomponent eutectogels as sustainable antioxidant materials

In this work, we obtained supramolecular gels in deep eutectic solvents (DES) from polysaccharides like chitosan and chitosan : cellulose composites. We thoroughly characterized our gels by determining the minimum gelation concentration, as well as their porosity and swelling. We also investigated their mechanical properties by rheology, and morphology by scanning electron measurements. These properties were mainly influenced by the number of hydrogen bond sites on the hydrogen bond donor, (HBD), while FTIR-ATR investigation suggested that, upon gelation, cholinium cations interpose between polysaccharide chains affecting interchain hydrogen bonding. Our gels also exhibited self-healing and…

Reattività di Z-arilidrazoni del 5-ammino-3-benzoil-1,2,4-ossadiazolo in presenza di acido tricloroacetico e di piperidina in toluene: confronto con i dati in diossano-acqua

Binding properties of heptakis-(2,6-di-O-methyl)-β-cyclodextrin and mono-(3,6-anhydro)-β-cyclodextrin: a polarimetric study

The binding constants for the inclusion complexes formed between heptakis-(2,6-di-O-methyl)-β-cyclodextrin (MβCD) and mono-(3,6-anhydro)-β-cyclodextrin (AβCD) with a set of suitably selected organic guests, were measured by means of polarimetry. Measurements were carried out at various pH values in order to ensure the correct protonation state for ionizable guests. Experimental data suggest that the binding properties of MβCD may be rationalized considering the less polar and more hydrophobic character of the cavity, although similar variations in conformational/dynamic behaviour occur as for native βCD. On the other hand, AβCD shows some similarities with αCD, due to the significant distor…

Effetto del cosolvente sulla velocità della reazione di trasposizione eterociclica mononucleare della Z-fenilidrazone del 3-benzoil-5-fenil-1,2,4-ossadiazolo in liquido ionico

Binding porperties of hetpakis-(2,6-di-O-methyl)-beta-cyclodextrin and mono-(3,6-anydro)-beta-cyclodextrin

Thermodynamics of binding between α- and β-cyclodextrins and some p-nitro-aniline derivatives: reconsidering the enthalpy–entropy compensation effect

Abstract The thermodynamics of binding between native α- and β-cyclodextrin towards several p -nitro-aniline derivatives was examined, in order to gain further insights about the occurrence of different interaction modes for the two hosts. Valuable information was achieved regarding the ‘expanded hydrophobic sphere’ of α-cyclodextrin. Furthermore, very interesting and unexpected aspects of the behavior of β-cyclodextrin were enlightened, such as the crucial role played by hydrogen bond interactions. Experimental data were examined under the perspective of the ‘enthalpy–entropy compensation effect’, and some ideas about this topic are discussed.

Carbon Nanomaterial Doped Ionic Liquid Gels for the Removal of Pharmaceutically Active Compounds from Water.

Due to large drug consumption, pharmaceutically active compounds (PhACs) can be found as water contaminants. The removal of PhACs is a significant issue, as they can easily overtake traditional purification methods. Because of their surface properties, carbon nanomaterials are among the most efficient materials able to adsorb PhACs. However, their limitation is their recovery after use and their possible leakage into the aquatic system. Consequently, new hybrid supramolecular ionic liquid gels (HILGs) have been designed for the adsorption of some antibiotic drugs (ciprofloxacin and nalidixic acid) from water. The chemical&ndash

Functionalized Diatonic Ionic Liquids Applied to the Study of Michael Addition

Spectrophotometric study on the thermodynamics of binding of α- and β-cyclodextrin towards some p-nitrobenzene derivativesElectronic supplementary information (ESI) available: Values of inclusion constants at different temperatures. See http://www.rsc.org/suppdata/ob/b3/b300330b/

Binding properties of native α- and β-cyclodextrin towards some nitrobenzene derivatives have been studied by means of UV-vis spectrophotometry. The former host is able to form complexes having 1 : 1 and 1 : 2 stoichiometric ratios with these guests, while only 1 : 1 complexes are detected with the latter host. A careful analysis of the thermodynamic parameters for complexation equilibria, under the perspective of the enthalpy–entropy compensation effect, reveals that binding abilities of the two different hosts are subject to different features.

Boosting the methanolysis of polycarbonate by the synergy between ultrasound irradiation and task specific ionic liquids

In an attempt to perform polycarbonate chemical recycling in a more sustainable way, we took into consideration the combined use of ultrasound irradiation and task specific ionic liquids. Towards this aim, the methanolysis of polycarbonate, into dimethylcarbonate and bisphenol A, was carried out in the presence of cholinium-based ionic liquids featuring anions derived from amino acids and other eco-friendly species. The target process was optimized in terms of both energy and material amounts as well as in terms of the nature of the catalysts used. The proposed protocol allowed high conversion and yields of bisphenol A to be obtained, under milder conditions compared to the ones so far repo…

Di- and Tricationic Organic Salts: An Overview of Their Properties and Applications

During recent years growing interest has been devoted to the synthesis and applications of polycationic organic salts. Among them, di- and tricationic organic salts can be considered the natural evolution of monocationic ones. These last have given rise to the large class of ionic liquids. In the cases of di- and tricationic organic salts, the potential to change their structural features simply by varying the properties either of the charged heads or of the spacers separating them provides the opportunity to obtain materials suitable for different applications. This review article highlights recent progress in the study of the properties of di- and tricationic organic salts, as well as in …

CONVERSIONE CHEMO-ENZIMATICA DI GLUCOSIO IN 5-HMF IN MISCELE IL/H2O, PROMOSSA DA ESTRATTO CELLULARE BATTERICO E ULTRASUONI

Di- and Tricationic Organic Salts: an Overview of Their Properties and Applications

During recent years growing interest has been devoted to the synthesis and applications of polycationic organic salts. Among them, di- and tricationic organic salts can be considered the natural evolution of monocationic ones. These last have given rise to the large class of ionic liquids. In the cases of di- and tricationic organic salts, the potential to change their structural features simply by varying the properties either of the charged heads or of the spacers separating them provides the opportunity to obtain materials suitable for different applications. This review article highlights recent progress in the study of the properties of di- and tricationic organic salts, as well as in …