579 research outputs found
Ionic liquids effects on the permeability of photosynthetic membranes probed by the electrochromic shift of endogenous carotenoids
No full textAbstractIonic liquids (ILs) are promising materials exploited as solvents and media in many innovative applications, some already used at the industrial scale. The chemical structure and physicochemical properties of ILs can differ significantly according to the specific applications for which they have been synthesized. As a consequence, their interaction with biological entities and toxicity can vary substantially. To select highly effective and minimally harmful ILs, these properties need to be investigated. Here we use the so called chromatophores – protein-phospholipid membrane vesicles obtained from the photosynthetic bacterium Rhodobacter sphaeroides– to assess the effects of imidazolinium and pyrrolidinium ILs, with chloride or dicyanamide as counter anions, on the ionic permeability of a native biological membrane. The extent and modalities by which these ILs affect the ionic conductivity can be studied in chromatophores by analyzing the electrochromic response of endogenous carotenoids, acting as an intramembrane voltmeter at the molecular level. We show that chromatophores represent an in vitro experimental model suitable to probe permeability changes induced in cell membranes by ILs differing in chemical nature, degree of oxygenation of the cationic moiety and counter anion
Multicomponent Cascade Synthesis of Biaryl-Based Chalcones in Pure Water and in an Aqueous Micellar Environment
No full textThe challenging multicomponent cascade synthesis of biaryl-based chalcones was carried out in pure water and in an aqueous micellar system. The first step of the protocol was a simple Pd-catalysed, ligand-free, and aerobic Suzuki–Miyaura reaction in aqueous medium. This proved to be extremely efficient for the coupling of aryl and heteroaryl bromides with different arylboronic acids. Subsequently, the resulting intermediates underwent an in-situ aldol condensation reaction to give biaryl(hetero)chalcones in good to excellent yields. When the protocol was applied to highly lipophilic or less reactive reagents, micellar catalysis was required for good results. To achieve this, we successfully used a new surfactant obtained from renewable resources that we recently designed. Furthermore, using this additive, the catalytic system can be repeatedly recycled without significant loss of activity
Surfactants from Itaconic Acid: Physicochemical Properties and Assessment of the Synthetic Strategies
No full textSurfactants are a wide class of compounds used in a broad spectrum of industrial and everyday applications. In this paper, we present the synthesis of a new family of surfactants having C12 and C18 alkyl chains obtained from itaconic acid and fatty amines, molecules industrially obtained from renewable resources. Main physicochemical properties of synthesized surfactants have been measured and their rheological behaviors have been evaluated at the air-water interface using the pendant drop technique. Some of the synthesized surfactants are stimuli responsive compounds, switchable to a polar form in the presence of CO2. The synthetic strategies have been optimized aiming at the sustainability of the process employing a complete set of green metrics and the software EATOS
Metodo per separare e recuperare polietilene e alluminio da un materiale poliaccoppiato
No full textL’invenzione fa riferimento ad una nuova tecnologia a base di switchable hydrophilic solvents (SHS) per la separazione e recupero di polietilene a bassa densità (LDPE) e alluminio da imballaggi alimentari (poliaccoppiato). Il nuovo metodo, interamente sostenibile, consente il recupero di entrambi i materiali in elevate quantità (> 99% per l'alluminio e > 80% per il polietilene) e buona qualità (≥ 86% di alluminio non ossidato). L’invenzione appartiene agli approcci chimici per separare LDPE e alluminio da residui sminuzzati di poliaccoppiat
Effects of ionic liquids on membrane fusion and lipid aggregation of egg-PC liposomes
No full textIn this study we have explored the effects of different groups of ionic liquids (ILs) on membrane fusion. The ILs used contain different head groups: N-methylimidazolium, 3-methylpyridinium and N-methylpyrrolidinium; short alkyl or ether functionalized side chains (with one or two ethoxy functionalities), paired with chloride anion. These ILs have been compared with 1-dodecyl-3-methylimidazolium bromide as example of a highly lipophilic IL. The effect of ILs on membrane fusion was investigated through pyrene steady state fluorescence probing, using the IE factor and excimer/monomer ratio (IE/IM) as parameters. The ratio between the vibronic bands of pyrene (I1/I3 ratio) has been used to monitor the effect of ILs on the aggregation properties of egg-PC liposomes. The effect of different ILs’ families was evident; the pyridinium ILs induced a greater extent of fusion than pyrrolidinium and imidazolium ILs having the same side chain. Marginal effect could be attributed to different anions. ILs with short alkyl chains were usually more effective than ether functionalized ones. The aggregation behaviors of ILs having dioxygenated chains have been measured in buffer solution
Shaping Calcite Crystals by Means of Comb Polyelectrolytes Having Neutral Hydrophilic Teeth
No full textComb polyelectrolytes (CPs) having neutral hydrophilic teeth, similar to double hydrophilic block copolymers, are a powerful tool to modify the chemical-physical properties of inorganic crystalline materials. One of their main applications is in concrete technology, where they work as superplasticizers, particle-dispersing agents. Here, CPs, having the same poly(acrylic acid) (PAA) backbone chain and differing in the grafting with methoxy poly(ethylene glycol) chains (MPEG) of two molecular weights, were used to investigate the influence of tooth chains in polymer aggregation and in control on morphology and aggregation of calcite particles. These polymers aggregate, forming interpolymer hydrogen bonds between carboxylic groups and ether oxygen functionalities. The presence of calcium ions in solution further enhances aggregation. Crystallization experiments of calcite in the presence of CPs show that the specificity of interactions between polymers and crystal planes and control on aggregation and size of particles is a function of the content and chain length of the MPEG in the PAA backbone. These parameters limit and can make specific the electrostatic interactions with ionic crystalline planes. Moreover, the mechanism of crystallization, classical or nonclassical, is addressed by the CP structure and concentration. These findings have implications in the understanding of the complex chemical processes associated to concrete superplasticizers action and in the study of the biomineralization processes, where biological comb polyelectrolytes, the acidic glycoproteins, govern formation of calcitic structures
Which kind of philosopher was Danilo Pejović?
No full textU ovom kratkom prilogu autorica pokušava opisati narav Danila Pejovića kao filozofa. Njegovo bitno obilježje bila je filozofijska i svetovna suverenost.In this short contribution the author tries to describe the nature of Danilo Pejović as a philosopher. His main characteristic was a philosophical and secular sovereignity
Application of switchable hydrophilicity solvents for recycling multilayer packaging materials
No full textA new procedure based on switchable hydrophilicity solvents (SHS) was proposed for polyethylene and aluminium recovery from food aseptic packaging. Treatment with N,N-dimethylcyclohexylamine (DMCHA) allowed very high material recovery (>99% for aluminium and >80% for polyethylene), without compromising the quality in terms of oxidation or polymer degradation. Moreover, the results from a simplified and preliminary life cycle analysis confirm the potential environmental benefits of a SHS approach compared with other treatment and disposal scenarios.A new procedure based on switchable hydrophilicity solvents (SHS) was proposed for polyethylene and aluminium recovery from food aseptic packaging. Treatment with N,N-dimethylcyclohexylamine (DMCHA) allowed very high material recovery (>99% for aluminium and >80% for polyethylene), without compromising the quality in terms of oxidation or polymer degradation. Moreover, the results from a simplified and preliminary life cycle analysis confirm the potential environmental benefits of a SHS approach compared with other treatment and disposal scenarios
Effects of ether-functionalized ionic liquids on membrane fusion related to their aggregation properties
No full textLIQUIDI IONICI: VALUTAZIONE DELL’ECOTOSSICITÀ E DEGLI EFFETTI BIOLOGICI
No full textGli aspetti (eco)tossicologici dei liquidi ionici, ed in generale la loro modalità di interazione con gli esseri viventi, sono stati valutati su
vari tipi di organismi bersaglio acquatici, tra cui invertebrati, alghe, batteri e su sistemi modello cellulari ed artificiali. La tossicità è
modulata principalmente dal carattere anfifilico delle sostanze, che determina la modalità di interazione con le membrane cellulari
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