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Bejaoui I.,UR Physico Chimie des Materiaux Solides | Bejaoui I.,University of Carthage | Baazaoui M.,UR Physico Chimie des Materiaux Solides | Baazaoui M.,University of Carthage | And 5 more authors.
Journal of Inclusion Phenomena and Macrocyclic Chemistry | Year: 2016

A series of positively charged β-cyclodextrin derivatives have been synthesized by selective functionalization of β-cyclodextrin at the primary rim with pyridinium groups. Characterisation of the modified β-cyclodextrin was done by elementary analysis, FTIR, 1H and 13C NMR spectroscopy. The inclusion complexation of adamantane derivatives (Adamantan-1-ol: AdOH and Sodium adamantane-1-carboxylate: AdCOO−Na+) by the host β-cyclodextrin and its grafted pyridinium derivatives has been investigated using 1H NMR spectroscopy. The stoichiometry of the complexes was found to be in 1:1 (adamantane:β-cyclodextrin) ratio. 1H chemical shift changes of adamantane protons were used to calculate the apparent binding constants of the complexes. Two dimentional NOESY experiments were performed to allow the mode of binding. Mono- and per-charged β-cyclodextrin showed an enhancement of inclusion binding ability towards the sodium adamantane-1-carboxylate guest. The origin of the observed enhancement in the stability of the complexes was ascribed to electrostatic interaction between carboxylate ion and charged pyridinium groups. A simple thermodynamic model of the electrostatic contribution to the complexation is presented. © 2016, Springer Science+Business Media Dordrecht.

Baazaoui M.,UR Physico Chimie des Materiaux Solides | Baazaoui M.,University of Carthage | Bejaoui I.,UR Physico Chimie des Materiaux Solides | Bejaoui I.,University of Carthage | And 4 more authors.
RSC Advances | Year: 2016

New cationic amphiphilic β-cyclodextrins (β-CD) were investigated for their surface-active properties and self-association. β-Cyclodextrin was mono- or per-substituted at its narrow rim by short (butyl) or long (dodecyl) aliphatic chains. The mono-substituted β-CDs are classical surfactants having a single hydrophobic tail and a single hydrophilic head; the per-substituted β-CDs have seven hydrophobic tails and seven hydrophilic heads. A comparative study of their surface-active properties at air/water and oil/water interfaces and of the formation of aggregates was achieved. All cationic β-CD surfactants show surface activity and self-assemble above a well-defined concentration referred to as the cmc because of the interactions between their hydrophobic tails. The inclusion of the alkyl chain inside the hydrophobic cavity did not cause other types of self-association. Though the main features of the surface-activity look similar to classical surfactants, such amphiphilic β-CDs show several specificities. The short-chained butyl derivatives behave as classical long-chained surfactants do. The head-tail interaction between the long dodecyl chain and the β-CD cavity of mono-substituted β-CD causes the formation of an intramolecular inclusion complex that weakens its hydrophobic character. The seven dodecyl chains of per-substituted β-CD tightly pack together, lowering the contact area with water and weakening their hydrophobic character. Part of the counterions of multi-charged per-substituted β-CD is associated as ion pairs with the cationic groups of the amphiphilic β-CD. A close analogy with the behavior of gemini surfactants is worth noticing. © The Royal Society of Chemistry 2016.

Baazaoui M.,UR Physico Chimie des Materiaux Solides | Baazaoui M.,University of Carthage | Bejaoui I.,UR Physico Chimie des Materiaux Solides | Bejaoui I.,University of Carthage | And 4 more authors.
Colloids and Surfaces A: Physicochemical and Engineering Aspects | Year: 2015

Aminoalkyl derivatives of β-cyclodextrin, in their neutral form are insoluble amphiphilic cyclodextrins that could be dispersed as nanoparticles in water. Such nanoparticles solubilize host molecules either in the non-polar medium in between the alkyl chains or in an environment of medium polarity inside the hydrophobic cavity of the cyclodextrins. This allows the solubilization of a wider range of molecules such as drugs, fragrances, aromas. . . than classical nanoparticles containing either oil or polymer. A series of such compounds either mono- or per-substituted at the C6 methylene of the β-CD primary rim with either short butyl chain or long dodecyl chain are obtained by chemical modification of native β-cyclodextrin with aminoalkyl groups. Their physicochemical properties and utilization for the manufacture of nanoparticles have been studied. The solubility assessed from direct microscopy observation and surface tension measurements were low; they were related to the hydrophobic character of the amphiphilic β-CDs, that is, the number and length of their alkyl chains. The monobutyl derivative adsorbs at the air-water interface as a monolayer whereas the most hydrophobic derivatives collapses into a 3-dimensional adsorbed layer. Stable nanoparticles were prepared by means of dispersion by ultrasound or by the nanoprecipitation method. Sonication yielded large and polydisperse nanoparticles of size larger than 500 nm; nanoprecipitation resulted in the formation of small nanoparticles with sizes in the range 100-200 nm with a narrow particle size distributions. © 2015 Elsevier B.V.

Ferchichi K.,UR Physico Chimie des Materiaux Solides | Hbaieb S.,UR Physico Chimie des Materiaux Solides | Amdouni N.,UR Physico Chimie des Materiaux Solides | Kalfat R.,Institute National Of Recherche Et Danalyse Physico Chimique | Chevalier Y.,University Claude Bernard Lyon 1
Materials Chemistry and Physics | Year: 2013

Composite materials that combine the lithium exchanging material LiCoO 2 and the conductive polymer poly(aniline) (PANI) have been investigated regarding their possible application to electrode materials of lithium batteries. Such composite materials have been prepared by means of polymerization of aniline in acidic suspensions of LiCoO2 particles. PANI was synthesized by oxidative polymerization of aniline by ammonium persulfate in the presence of sodium dodecylbenzenesulfonate (SDBS) as a micellar template and dopant. The composite material consisted in LiCoO 2 particles dispersed in a continuous matrix of PANI. The ribbon-like morphology of the powdered material was distinctly different of the morphologies of the parent materials. The conductive material had conductivity close to that of PANI because the LiCoO2 content of the composite material was low. The presence of the poorly conductive inorganic phase caused a significant loss of conductivity, showing that LiCoO2 blocked electronic transfers between PANI crystallites. Ammonium persulfate caused the loss of lithium from LiCoO2 when it was used at high concentration in the polymerization recipe. In this case a new phase made of Co 3O4 formed by chemical decomposition of Li xCoO2. Thin films prepared from stable suspensions of composite materials in water show comparable electrical performance to that measured for bulk materials. © 2013 Elsevier B.V. All rights reserved.

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