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International audience; Levoglucosan (LGA) is an anhydrous pyrolytic sugar that has gained increasing attention in recent years. The highest focus on the conversion of LGA and other anhydro carbohydrates obtained from cellulose aims at the valorization of these molecules and their application in multiple fields such as chemical and pharmaceutical industries. LGA presents a rigid structure with three hydroxyl groups on a pyranose ring, making it a promising building block for the synthesis of bio-based thermoplastic polymers with pending OH groups as soon as a regioselective polymerization is reached. In this work, a lipase-catalyzed series of LGA-containing terpolymers were synthesized for the first time via regioselective transesterification in two-stage polymerization. LGA was reacted with diethyl adipate/sebacate and α,ω-diols to give terpolymers with up to 35% of LGA content (related to the α,ω-diol content), number-average molecular weights (Mn) of up to 7900 g·mol–1, and up to 94% yield. It was observed that the amount of LGA in the polymer structure affects the crystallinity, hydrophilicity, and melting point of the polymers. We also evaluated the effect of LGA loading and the comonomer’s size on yields, molecular weight, and the incorporation of LGA in the polymer structure. High loads of LGA lead to a decrease in the yield, but a higher molecular weight and higher extent of LGA incorporation in the polymer can be obtained.

International audience; Furan-2,5-dicarboxylic acid has been introduced in recent years as a green aromatic monomer toward the design of aromatic (co)polyesters with enhanced properties, i.e., polyethylene furanoate (PEF) that can definitely compete with its petroleum-based counterpart, i.e., polyethylene terephthalate (PET). In an attempt to produce biobased semiaromatic copolyesters in an efficient eco-friendly approach, we report herein the polycondensation of diethyl furan-2,5-dicarboxylate (DEFDC) with different aliphatic diols and diesters of variable chain length catalyzed by an immobilized lipase from Candida antarctica using a two-step polymerization reaction carried out in diphenyl ether. The influence of diol and diester chain length, the molar concentration of DEFDC, and the effect of enzyme loading were assessed via nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and wide-angle X-ray scattering (WAXS). With high quantities of DEFDC, significant differences in terms of M̅n buildup were noticed. Only longer diols starting from octane-1,8-diol successfully reacted with up to 90% DEFDC as opposed to only 25% DEFDC reacting with short diols such as butane-1,4-diol. While varying the chain length of the diester, it was evident that shorter diols such as hexane-1,6-diol have better reactivity toward longer diesters, while dodecane-1,12-diol was reactive toward all tested diesters. The incorporation of long chain fatty dimer diols such as Pripol 2033 led to polyesters with higher M̅n and was successfully used to overcome the limitations of poor reactivity observed in the case of short diols in the presence of high furan content. The DSC results showed a pseudoeutectic behavior as a function of increasing the mol % of DEFDC, and a change in the crystalline phase was confirmed via WAXS analysis. Finally, this work showed the successful enzyme-catalyzed synthesis of several DEFDC biobased semiaromatic copolyesters with variable interesting properties that can be further optimized for possible applications in food packaging as well as other possibilities.; L'acide furane-2,5-dicarboxylique a été introduit ces dernières années en tant que monomère aromatique vert pour la conception de (co)polyesters aromatiques aux propriétés améliorées, comme le polyéthylène furanoate (PEF) qui peut définitivement concurrencer son homologue issu du pétrole, le polyéthylène téréphtalate (PET). Dans le but de produire des copolyesters semi-aromatiques d'origine biologique par une approche efficace et respectueuse de l'environnement, nous rapportons ici la polycondensation du furan-2,5-dicarboxylate de diéthyle (DEFDC) avec différents diols et diesters aliphatiques de longueur de chaîne variable, catalysée par une lipase immobilisée de Candida antarctica, en utilisant une réaction de polymérisation en deux étapes réalisée dans de l'éther diphénylique. L'influence de la longueur de chaîne des diols et des diesters, la concentration molaire de DEFDC, ainsi que l'effet de la charge enzymatique ont été évalués par Résonance Magnétique Nucléaire (RMN), chromatographie par perméation de gel (CPG), calorimétrie différentielle à balayage (DSC) et diffusion des rayons X à angle large (WAXS). Sans DEFDC, ou à faible teneur, l'augmentation de la longueur du diol n'a pas eu d'effet négatif sur la masse moléculaire moyenne en nombre (Mn) des copolyesters aliphatiques préparés. En revanche, lorsque des quantités élevées de DEFDC (plus de 40 % molaire) ont été ajoutées dans le milieu réactionnel, des différences significatives en termes d'accumulation de Mn ont été remarquées. Seuls les diols plus longs à partir de l'octane-1,8-diol ont été mis en réaction avec succès avec jusqu'à 90% de DEFDC, par opposition à seulement 25% de DEFDC avec des diols courts tels que le butane-1,4-diol. Le Mn obtenu a montré une tendance à diminuer en fonction de l'augmentation du % d'alimentation en DEFDC, surtout avec les diols courts où la diminution du Mn était plus prononcée. En faisant varier la longueur de la chaîne du diester, il était évident que les diols plus courts tels que l'hexane-1,6-diol ont une meilleure réactivité vis-à-vis des diesters plus longs, tandis que le dodécane-1,12-diol était réactif vis-à-vis de tous les diesters testés. L'incorporation de diols dimères gras à longue chaîne tels que le Pripol 2033 dans le milieu réactionnel a conduit à des polyesters avec un Mn plus élevé et a été utilisé avec succès pour surmonter les limitations de la faible réactivité observée dans le cas des diols courts en présence d'une teneur élevée en furanes. Les résultats de la calorimétrie différentielle à balayage (DSC) ont montré un comportement pseudo-eutectique caractérisé par une diminution du point de fusion (Tm) en fonction de l'augmentation du % molaire de DEFDC, suivie d'une augmentation à un % molaire plus élevé deࣙࣙ DEFDC (≥ 50%) et un changement de la phase cristalline confirmé par une analyse de diffusion des rayons X à grand angle (WAXS). Enfin, ce travail a montré la synthèse réussie par catalyse enzymatique de plusieurs copolyesters semi-aromatiques biosourcés avec des propriétés intéressantes variables, à base de DEFDC.

The chain shuttling ring-opening copolymerization of l-lactide with ε-caprolactone has been achieved using two aluminum catalysts presenting different selectivities and benzyl alcohol as chain transfer agent. A newly synthesized aminobisphenolate supported aluminum complex affords the synthesis of lactone rich poly(l-lactide

The epimerization of polylactide is reported in the presence of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) at 105°C in toluene. The extent of the reaction depends on the amount of TBD introduced and the reaction time. Up to ca. 46% D units can be formed starting from poly(L-lactide) in the presence of 5 mol% TBD. The epimerization rate is slightly higher for D-stereoisomers vs. L-stereoisomers. From the decrease of the number-average molecular weight observed, a concomitant chain scission reaction is observed. A possible mechanism based on a nucleophilic attack of TBD is proposed based on NMR analyses, notably DOSY, MALDI ToF mass spectrometry and IR spectroscopy. The implications of the work in the field of polymer synthesis and chemical recycling of polylactide are discussed. 181;109188

Synthetic Vascular Graft Infection (SVGI) can be very serious for patients with dramatic consequences (up to 6%). Polyester vascular grafts (PET) were modified with polymerized cyclodextrin (Poly-MeβCD) and loaded with ciprofloxacin (CFX) for the prevention of postoperative infections. The aim of this study was to investigate the CFX/Poly-MeβCD interactions and the importance of the type of the dissolution technique. The solubility of CFX was significantly improved upon Poly-MeβCD, and the interaction between CFX and Poly-MeβCD were observed by NMR (Nuclear Magnetic Resonance). Drug release was measured in phosphate buffer saline pH 7.4 at 37 °C using: (i) agitated flasks, (ii) the paddle apparatus, (iii) the conventional flow-through cells, (iv) the modified flow-through cells with agarose gel at different flow rates. Importantly, CFX release depends on the flow rate as well as the experimental set-up in vitro. CFX release from virgin prostheses (PET) was faster than from functionalized prostheses (PET-MeβCD), irrespective of the flow rate, which indicates the superiority of Poly-MeβCD in the control of CFX release. The CFX diffusion from PET-MeβCD into agarose gel showed a continuously progressive diffusion during 7 days. Thus, this test can be highly appropriate for in vitro characterization of such drug delivery systems. 53

In this paper, poly(vinyl alcohol) (PVOH) cast films were crosslinked with citric acid (CTR) and hydroxypropyl-β-cyclodextrin (HPβCD) and loaded with sodium benzoate (NaBz) as preservative agent, with different compositions of CTR (10–30 wt%) and NaBz (0–6 wt%) with or without HPβCD (10%). Permeability tests showed that the presence of CTR and HPβCD does not modify PVOH barrier properties. Before incorporation, the complex formation of HPβCD with NaBz was investigated through 2 dimensional Nuclear Magnetic Resonance, which revealed a 1:1 stoichiometry. Raman spectroscopy cartography showed that the NaBz distribution in the films was homogeneous, especially with HPβCD. The NaBz release in water is prolonged with HPβCD on one hand for high crosslinking times (360 min) and, on the second hand, in the assays carried out at low temperature (4 °C). The released quantity is increased from 40% to 70% when NaBz is included into HPβCD cavity. Antimicrobial assays were performed against Staphylococcus aureus, Escherichia coli and Candida. Without HPβCD, all films present a contact antimicrobial activity thanks to grafted CTR and the best diffusion activity was obtained for 6 wt% NaBz for the three microorganisms. With HPβCD, the antimicrobial activity by diffusion was increased with crosslinking times.

The coating of a nonwoven textile by polyelectrolyte multilayer film (PEM) issued from cationic and anionic β-cyclodextrin (βCD) polyelectrolytes according to the layer-by-layer (LbL) technique was successfully attempted. The tert-butyl benzoic acid (TBBA) was used as drug model to evaluate the loading capacity and sustained release properties of this PEM system. The build-up of the multilayer assembly was monitored in situ by optical waveguide lightmode spectroscopy (OWLS) on the one hand, and was assessed by gravimetry on the other hand when applied onto the textile substrate. In parallel, the complexation study of TBBA with both CD polyelectrolytes was also investigated by nuclear magnetic resonance (NMR) and isothermal titration calorimetry (ITC). The influence of thermal crosslinking of the multilayered coating on its stability and on TBBA release kinetics in phosphate buffered saline (PBS) at 37°C was studied. Finally, biological and microbiological tests were performed to investigate the cytocompatibility and the intrisic antibacterial activity of multilayer assemblies. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1408-1424, 2016.

International audience; End-functionalized 1,4-trans-polydienes (isoprene and myrcene) were prepared by means of a neodymium-mediated continuous polymerization–functionalization process. A chain transfer stage was essential to get a high level of functionalization of the polymer. The living 1,4-trans-stereoregular polymer chain was reacted with benzophenone to afford up to 97% −CPh2OH end-group with isoprene, while in the case of myrcene, using the same strategy afforded 1,4-trans-polymyrcene with a functionalization rate of 83%. The strategy was validated with complementary functionalization experiments using benzaldehyde and styrene oxide, both affording 95% end-capped trans-stereoregular polydienes.

The aim of the study was to develop a polyester visceral implant modified with a cyclodextrin polymer for the local and prolonged delivery of ropivacaine to reduce post operatory pain. Therefore, we applied a coating of an inguinal mesh with a crosslinked polymer of hydroxypropyl-β-cyclodextrin (HPβCD) whose specific host–guest complex forming properties were expected to improve the adsorption capacity of the implant toward anesthetic, and then to release it within a sustained period. The modification reaction of the textile with cyclodextrin was explored through the study of the influence of the pad/dry/cure process parameters and the resulting implant (PET–CD) was characterized by solid state NMR and SEM. Besides, the inclusion complex between ropivacaine and CD was studied by NMR and capillary electrophoresis in PBS medium. Finally, ropivacaine sorption test showed that a maximum of 30 mg/g of ropivacaine could be adsorbed on the functionalized samples. In dynamic batch tests in PBS at pH 7.4, the release could be observed up to 6 h. The cytocompatibility of the PET–CD loaded with ropivacaine was also studied and reached 65% cell vitality after 6 days.

The microstructural analysis of 1,4-cis- and of 1,4-trans-polymyrcene was conducted by means of thorough investigations at a very high field NMR (21.1T, 900 MHz). A set of 1D and 2D experiments helped to entirely assign the resonances of the spectra for both stereoisomers. A simple method to distinguish between each stereoisomer by NMR spectroscopy is finally provided.

International audience; Isoprene chain shuttling polymerisation between the 1,4-trans regulating Cp*La(BH4)2(THF)2/MgnBuEt (Cp* = C5Me5) and the 1,4-cis regulating NdCl3(THF)2/AlR3 (R = Et or iBu) systems provides access to stereoblock polyisoprene. Under selected experimental conditions, the trans segments are semi-crystalline, leading to a thermoplastic elastomer-like material.

The Cp*La(BH4)2(THF)2/n-butylethylmagnesium (BEM) catalytic system has been assessed for the coordinative chain transfer copolymerization of styrene and 1-hexene. Poly(styrene-co-hexene) statistical copolymers were obtained with number-average molecular weight up to 7600 g/mol, PDI around 1.4 and 1.5 and up to 23% hexene content. The occurence of chain transfer reactions in the presence of excess BEM is established in the course of the statistical copolymerization. Thanks to this transfer process, the quantity of 1-hexene in the copolymer is increased by a factor of about 3 for high ratio of hexene in the feed, extending the range of our concept of a chain transfer induced control of the composition of statistical copolymers to poly(styrene-co-hexene) copolymers. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

A textile polyester vascular graft was modified with methyl-β-cyclodextrin (MeβCD) to obtain a new implant capable of releasing antibiotics directly in situ at the site of operation over a prolonged period and thereby prevent post-operative infections. We investigated the influence of the curing parameters (time and temperature) that allow control of the degree of functionalization (DF) of the support by MeβCD. The inclusion of ciprofloxacin (CFX) in the MeβCD cavity was observed in solution by two-dimensional 1H NMR spectroscopy. The amount of CFX loaded on the modified graft increased with DF. Depending on the release medium (water, phosphate-buffered saline, or human plasma) and the DF of the prostheses, different kinetic profiles of release of CFX were obtained. The sustained release of CFX in human plasma was shown by microbiological assays that indicated prolonged antimicrobial activity against Staphylococcus aureus and Escherichia coli. Viability tests demonstrated the non-toxicity of MeβCD to an epithelial cell line (HPMEC), although a decrease in endothelial cell number was observed on the functionalized prosthesis, probably due to the roughness of the coating and also to the nature of the MeβCD polymer present on the surface of the fibers.

The synthesis of a polypseudorotaxane, polyrotaxane, and polycatenane containing the electron-deficient cyclophane cyclobis(paraquat-p-phenylene) (CBPQT4+) subunit in the side chain is described. These interlocked supramolecular polymers have been prepared from an azide-functionalized polystyrene derivative and an acetylene-functionalized [2]rotaxane, [2]catenane and their parent tetracationic cyclophane via Cu(I)-catalyzed 1,3 dipolar cycloadditions (‘click chemistry’). The synthesis and characterization of the polymers and intermediates has been described using IR, 1H NMR, UV spectroscopies, and voltammetry. We have shown that the CBPQT4+ unit of the side chain polystyrene derivative has the ability to reversibly undergo complexation with a complementary dialkoxynaphthalene derivative.

For the first time, we announce the synthesis of cyclo(bis-paraquat-p-phenylene-p-phenylene-carbonyl)tetrakis(hexafluorophosphate), named ‘CETOBOX’. This compound exists in three tautomeric forms. These forms were evidenced by NMR data (1H NMR, TOCSY, COSY, and NOESY), UV–vis spectra coupled with pH measurements, and by synthesis. As the ‘CETOBOX’ gives ‘in situ’ only the corresponding monoylide, the synthesis of a new fluorescent indolizine cyclophane has been performed by a 3+2 cycloaddition. This cycloadduct, in an amidation reaction with 6-amino-β-cyclodextrin, furnishes the final two-cavity sensor with good yields. All structures of the new compounds presented herein have been established by NMR spectroscopy. Also, theoretical methods (MM3, AM1, AM1 (COSMO), and B88LYPDFT) have been used to determine the most stable conformer structures. For the fluorescent indolizine cycloadduct, we evaluated its inclusion capabilities and for the two-cavity sensor, we measured some of its electrical properties that make it suitable for use in VOCs detection and energy conversion.

Two original Chain Transfer Agents (CTAs) integrating either a nitrocatechol or a boronic acid moiety were synthesized allowing the conception of a wide library of end-functionalized well-defined homopolymers via the Reversible Addition–Fragmentation chain Transfer (RAFT) process. Kinetic studies using NMR spectroscopy and Size Exclusion Chromatography (SEC) were carried out, revealing good control of polymerizations of various monomers. Then, a coupling reaction between the complementary nitrocatechol and boronic acid end-chain polymers was optimized to create a dynamic boronate ester junction between the polymer blocks. The effectiveness of the reaction was demonstrated by means of NMR (1H, DOSY), SEC and cyclic voltammetry. The ability of the covalent bond, and thus the block copolymers, to be disrupted on demand was assessed using a competitive molecule (2-naphthylboronic acid) and UV irradiation as stimuli.

Nucleobase-functionalized polymers are widely used in the fields of supramolecular chemistry and self-assembly, and their development for biomedical applications is also an area of interest. They are usually synthesized by tedious multistep procedures. In this study, we assess adenine as an organoinitiator/organocatalyst for the ring-opening polymerization of lactide. L-Lactide can be quantitatively polymerized in the presence of adenine. Reaction conditions involving short reaction times and relatively low temperatures enable the access to adenine end-capped polylactide in a simple one-step procedure, in bulk, without additional catalyst. DFT calculations show that the polymerization occurs via hydrogen bond catalysis. The mechanism involves (i) a hydrogen bond between the NH9 of adenine and the carbonyl moiety of lactide, leading to an electron deficient carbon atom, and (ii) a second hydrogen bond between the N3 of adenine and the NH2 of a second adenine molecule, followed by a nucleophilic attack of the latter activated amine on the former electron deficient carbon on the monomer. For longer reaction times and higher temperatures, macrocyclic species are formed, and a mechanism involving the imidazole ring of adenine is proposed based on literature studies. Depending on the reaction conditions, adenine can thus be considered as an organoinitiator or an organocatalyst for the ring-opening polymerization of lactide.

This Letter, describes the complexation of α-, β- and γ-cyclodextrins (1–3) with TTF derivative 4 in water. In particular, we show using 1H, 13C NMR, UV–vis spectroscopy and isothermal titration calorimetry that β-cyclodextrin 2 forms an effective complex with 4. Complex 2·4 can be conveniently disassembled upon the addition of 1-adamantanol.

This article reports the characterization of pseudorotaxanes fabricated from cyclobis(paraquat-p-phenylene) 1, and 1,4-dialkyloxyphenyl derivative 2 or 1,5-dialkyloxynaphthalene derivative 3 in water. Addition of competing guest 3 to 1.2 or the electrochemical reduction of the cyclophane of 1.3 results in a dethreading of the original pseudorotaxane architecture.

The coating of a nonwoven textile by polyelectrolyte multilayer film (PEM) issued from cationic and anionic β-cyclodextrin (βCD) polyelectrolytes according to the layer-by-layer (LbL) technique was successfully attempted. The tert-butyl benzoic acid (TBBA) was used as drug model to evaluate the loading capacity and sustained release properties of this PEM system. The build-up of the multilayer assembly was monitored in situ by optical waveguide lightmode spectroscopy (OWLS) on the one hand, and was assessed by gravimetry on the other hand when applied onto the textile substrate. In parallel, the complexation study of TBBA with both CD polyelectrolytes was also investigated by nuclear magnetic resonance (NMR) and isothermal titration calorimetry (ITC). The influence of thermal crosslinking of the multilayered coating on its stability and on TBBA release kinetics in phosphate buffered saline (PBS) at 37°C was studied. Finally, biological and microbiological tests were performed to investigate the cytocompatibility and the intrisic antibacterial activity of multilayer assemblies. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1408-1424, 2016.

We report the synthesis of a cyclodextrin-based molecular adapter which has the propensity to form an electrochemically tuneable ternary complex with cyclophanes 2 or 3 and ferrocene 4 in non-aqueous and aqueous environments, respectively.

[reaction: see text] A new self-complexing donor-acceptor system has been synthesized that has the propensity to undergo intramolecular decomplexation under thermal and electrochemical perturbation and upon addition of a competitive guest for the cyclophane's cavity.

Oxovanadium(IV) complexes of hydroxysalen derivatives have been prepared and tested as DNA reactive agents. The nuclease activity has been investigated under oxidative or reducing conditions, on the basis of the various oxidation states of vanadium: V(III), V(IV) and V(V). In the absence of an activating agent, none of the compounds tested was able to induce cleavage of DNA, whereas in the presence of mercaptopropionic acid (MPA) or Oxone the four complexes induced DNA modifications. Under both conditions, the para-hydroxy complex was found to be the most active compound. Reaction of these salen complexes with DNA occurs essentially at guanine residues and is more efficient in the presence of Oxone than under reducing conditions. The extent of Oxone-mediated DNA oxidation by the four vanadyl complexes was clearly superior to VOSO(4) and was observed without piperidine treatment. EPR studies provided information on the reactive metal-oxo species involved under each conditions and a mechanism of reaction with DNA is discussed.

The 1,3-dipolar cycloaddition reaction of bipyridinium ylides with the electron deficient propynamido-β-cyclodextrin was studied. This reaction resulted in the regiospecific formation of a new class of fluorescent β-cyclodextrins. The new fluorophore systems were characterized spectroscopically by their absorption and emission maxima and their quantum yields.

New bis(phenolate)amine-supported neodymium borohydride complexes and their previously reported samarium analogues were tested as catalysts for the polymerisation of styrene and isoprene. Reaction of Na2O2NL (L = py, OMe, NMe2) with Nd(BH4)3(THF)3 afforded the borohydride complexes Nd(O2NL)(BH4)(THF) (L = py (1-Nd), OMe (2-Nd), NMe2 (3-Nd)). Complex 1-Nd has shown a propensity to form phenolate-O-bridged dimer [Nd(μ-O2Npy)(BH4)]2 (1′-Nd) as previously observed with the samarium analogues Sm(O2NL)(BH4)(THF) (L = py or Pr). X-ray structures of 1′-Nd and 2-Nd were determined and are presented. The neodymium borohydride complexes 1-Nd to 3-Nd and their samarium analogues Sm(O2NL)(BH4)(THF)x (L = py (1-Sm), OMe (2-Sm), NMe2 (3-Sm), Pr (4-Sm)) were tested as catalysts for the polymerisation of isoprene and styrene in the presence of n-butylethylmagnesium (Mg(nBu)(Et)). All complexes were found to be active for the polymerisation of isoprene in these conditions, leading to polyisoprene up to 95.1% trans-1,4 stereoregular. They were also found to be active for the polymerisation of styrene leading to atactic polystyrene in all cases. Interestingly, samarium-based complexes were found to be more active than the neodymium ones toward this latter monomer, in sharp contrast to what is usually observed with rare earth borohydride complexes. The structure of both trans-polyisoprenes and polystyrenes obtained were studied in detail by MALDI-ToF analysis in order to better understand the polymerisation mechanisms. The coordinative chain transfer polymerisation (CCTP) of both monomers was further conducted using Mg(nBu)(Et) as transfer agent. Finally, the statistical copolymerisation of isoprene and styrene was examined using these catalytic systems, leading to the formation of poly[(trans-1,4-isoprene)-co-styrene] with up to 39% of styrene moieties inserted in a highly trans-1,4-stereoregular polyisoprene.

Mixtures of ionic liquids (ILs) with polar aprotic solvents in different combinations and under different conditions (concentration, temperature etc.) are used widely in electrochemistry. However, little is known about the key intermolecular interactions in such mixtures depending on the nature of the constituents and mixture composition. In order to systematically address the intermolecular interactions, the chemical shift variation of 1H and 13C nuclei has been followed in mixtures of imidazolium ILs 1-n-butyl-3-methylimidazolium tetrafluoroborate (BmimBF4), 1-n-butyl-3-methylimidazolium hexafluorophosphate (BmimPF6), 1-n-butyl-3-methylimidazolium trifluoromethanesulfonate (BmimTfO) and 1-n-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BmimTFSI) with molecular solvent acetonitrile (AN) over the entire composition range at 300 K. The concept of relative chemical shift variation is proposed to assess the observed effects on a unified and unbiased scale. We have found that hydrogen bonds between the imidazolium ring hydrogen atoms and electronegative atoms of anions are stronger in BmimBF4 and BmimTfO ILs than those in BmimTFSI and BmimPF4. Hydrogen atom at position 2 of the imidazolium ring is substantially more sensitive to interionic hydrogen bonding than those at positions 4–5 in the case of BmimTfO and BmimTFSI ILs. These hydrogen bonds are disrupted upon dilution in AN due to ion dissociation which is more pronounced at high dilutions. Specific solvation interactions between AN molecules and IL cations are poorly manifested.

The intermolecular interactions in 1-n-butyl-3-methylimidazolium acetate (BmimAc)/water mixture were studied by examining the mole fraction dependence of the vibrational modes measured with infrared and Raman spectroscopy, as well as of the 1H, 13C, 15N and 17O NMR chemical shifts. Quantum chemistry calculations were carried out to assign as clearly as possible the vibrational modes of the cation and anion as well as to get information on the expected effect of the mixture composition on the vibrational modes and charge distribution in BmimAc.The behavior of the obtained spectroscopic data is consistent with the physical picture that when water is added to BmimAc, the interactions between cation–anion are weakened in favor of those between water and anion. The clear spectral signature is associated with the strong blue/red shift of the stretching and bending modes of the C(2)–H, respectively. Consistently with this spectral behavior, the corresponding 1H and 13C chemical shifts decrease when adding water to BmimAc. The strengthening of the water–anion interactions is also traced back to both the blue shift of the νs(COO−) at around 1380 cm-1 and ν(C–C) of acetate at around 920 cm-1 as well as the blue shift of the δ(COO−) at around 637 cm-1 and ω(COO−) at 615 cm-1. The 1H, 13C and 17O chemical shifts of COO− are consistent with the corresponding spectral behavior.

In order to study the effect of phenol moieties on biological activities of ascorbic acid derivatives, we synthesized 13 novel 4,5-diaryl-3-hydroxy-2(5H)-furanones 5a-m with various substitution patterns. Compound 5 g bearing a 2,3-dihydroxy phenyl ring on the 5-position of the heterocycle appeared to be the most powerful anti-oxidant furanone with reducing activity against DPPH (IC(50)=10.3 microM), superoxide anion quenching capacity (IC(50)=0.187 mM) and lipid peroxidation inhibitory effect (IC(50)=0.129 mM). To ascertain determinant molecular features for anti-oxidant activities, structure-activity relationships were studied. Lipophilicity and molecular parameters related to electron distribution and structure (difference in heats of formation between the compound and its radical or its cation radical, energy of the highest occupied molecular orbital, HOMO) were found to correlate with the anti-oxidant action of compounds 5 in the different tests used. Oxygen-derived free radicals are known to contribute to inflammatory disorders; therefore we have investigated effects of compounds 5 in two models of inflammation: phorbol ester-induced ear edema in mice (TPA-test) and carrageenan-induced paw edema in rat. At 100 mg/kg ip in the TPA-test, the anti-inflammatory activity of compounds 5 was potent compared with that of indomethacin and ketorolac and all the results suggested a cyclooxygenase inhibition in the emergence of such properties. The combined pharmacological actions of compounds 5 associated with a favorable therapeutic index prompt with interesting perspectives for their use in heart and brain disorders as well as in inflammatory diseases.

( R )-(+)-binaphathyl-diyl hydrogen phosphate (R-BNPH) / diazabicyclo[5.4.0]undec-7-ene (DBU) and (1 R )-(−)-10-camphorsulfonic acid (CSA) / 4-dimethylaminopyridine (DMAP) acid-base salts are synthesized and assessed for the ring-opening polymerization of rac -lactide. They are found to be inactive toward the polymerization in the presence of a protic initiator. When used in combination with a base such as DBU or DMAP and a protic initiator, these acid / base conjugates lead to well controlled polymerization in mild conditions (D M

The polymerization of e-caprolactone (e-CL) has been assessed in water using various Bronsted acids as catalysts. The reaction was found to be quantitative at 100 °C, leading to number–average molecular weights up to 5000 g mol−1. The Bronsted acid-catalyzed polymerization of e-CL in water was further conducted in the presence of water-soluble polysaccharides thereby affording graft copolymers. The approach enables an easy, mild access to dextran hydroxyesters. For low degree of substitution, the latter self-assembles in water to form nanoparticles. Poly(e-CL)-graft-methylcellulose copolymers can also be obtained via a similar approach. It is noteworthy that the methodology reported herein is a one-step route to poly(e-CL)-graft-water-soluble polysaccharides, operating in mild conditions, that is, at low temperatures, using readily available metal-free catalysts and water as a solvent. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2139–2145

A new class of polymeric thermometers with a memory function is reported that is based on the supramolecular host-guest interactions of poly(N-isopropylacrylamide) (PNIPAM) with side-chain naphthalene guest moieties and the tetracationic macrocycle cyclobis(paraquat-p-phenylene) (CBPQT(4+)) as the host. This supramolecular thermometer exhibits a memory function for the thermal history of the solution, which arises from the large hysteresis of the thermoresponsive LCST phase transition (LCST = lower critical solution temperature). This hysteresis is based on the formation of a metastable soluble state that consists of the PNIPAM-CBPQT(4+) host-guest complex. When heated above the transition temperature, the polymer collapses, and the host-guest interactions are disrupted, making the polymer more hydrophobic and less soluble in water. Aside from providing fundamental insights into the kinetic control of supramolecular assemblies, the developed thermometer with a memory function might find use in applications spanning the physical and biological sciences.

A well-defined poly(N-isopropyl acrylamide) 1 incorporating at one termini a cyclobis(paraquat-p-phenylene) (CBPQT(4+)) recognition unit is prepared via a RAFT polymerization followed by a copper-catalyzed azide-alkyne cycloaddition (CuAAC). (1)H NMR (1D, DOSY), UV-vis and ITC experiments reveal that polymer 1 is able of forming effective host-guest complexes with tetrathiafulvalene (TTF) end-functionalized polymers in water, thereby leading to the formation of non-covalently-linked double-hydrophilic block copolymers. The effect of the temperature on both the LCST phase transition of 1 and its complexes and on CBPQT(4+)/TTF host-guest interactions is investigated.

The photophysical properties of a pH dependent molecular switch based on pyridin-4-yl indolizin β-cyclodextrin 1 in water are described. The reversibility phenomena of fluorescent emission is attributed to a molecular motion of enclosed fluorescent moiety to inside/outside location.

The interactions between β-cyclodextrin and a hydrosoluble polymer carrying hydrophobic residues: poly(4-sodium styrenesulfonate) have been studied. Several techniques were used: capillary viscosimetry, circular dichroism, and NMR spectroscopy. The results proved that the aromatic residues of NaPSS were included in the cavity of β-cyclodextrin, and that, in addition, a network of hydrogen bonding between sulfonic acid residues and the hydroxyl groups of β-cyclodextrin occured.

A well-defined cyclobis(paraquat-p-phenylene) (CBPQT4+) end-functionalized poly(n-butyl acrylate) 3 was prepared via RAFT polymerization using a new trithiocarbonate CBPQT4+ derivative 2 as a reversible chain transfer agent. We have shown that the electron-poor CBPQT4+ moiety at the α-chain-end could be specifically modified by complex formation with various functionalized macromolecules featuring complementary electron rich end groups, thereby leading to the corresponding supramolecular diblock copolymers. The latter could be conveniently disassembled upon heating, by applying electrochemical redox processes or by the addition of a competing molecular guest. Furthermore, we can generate new diblock architectures upon the addition of an appropriately functionalized polymer. We also describe preliminarily results regarding the formation of nanostructured architectures both in solution and in thin films.

The main aim of this paper is to quantify the inhomogeneous distribution of the components of acetone/methanol mixture and to give detailed insight into the interplay between the dipole-dipole and hydrogen bonding interactions inducing this inhomogeneity. To this end, we used the concept of infrared excess molar absorption of a given vibrational mode as an observable which contains all the information on the collective interactions in the mixture. Indeed, the changes in the infrared excess molar absorption may be associated with the inhomogeneous distribution (clustering, self-association, or high-density domains) of the components and consequently with the interaction between the two components of the mixture. The results show that acetone molecules are not homogeneously distributed in the mixture, particularly in the mole fraction range of acetone between 0.05 and 0.55. The spectral signature of this inhomogeneity is associated with the appearance of a shoulder in the C=O and C-C stretching vibrational profiles of acetone. This inhomogeneity is driven by the prevalence of the dipole-dipole interactions over those of hydrogen bonding between acetone and methanol molecules. The inhomogeneous distribution of methanol molecules is found to occur in the mole fraction range of acetone between 0.55 and 1. In this case, the hydrogen bond interactions between methanol molecules prevail over those between methanol and acetone. However, the extent of this inhomogeneity is small compared with that of acetone in the low mole fraction range. The spectral signature of this inhomogeneity is not visible in the O-H stretching vibrational mode; however, a second peak appears as a shoulder of the C-O stretching vibrational mode in this range of acetone mole fraction.

Self-diffusion coefficients of cations and solvent molecules were determined with 1H NMR in mixtures of 1-n-butyl-3-methylimidazolium (Bmim+) tetrafluoroborate (BF4–), hexafluorophosphate (PF6–), trifluoromethanesulfonate (TfO–), and bis(trifluoromethylsulfonyl)imide (TFSI–) with acetonitrile (AN), γ-butyrolactone (γ-BL), and propylene carbonate (PC) over the entire composition range at 300 K. The relative diffusivities of solvent molecules to cations as a function of concentration were found to depend on the solvent but not on the anion (i.e., IL). In all cases the values exhibit a plateau at low IL content (xIL < 0.2) and then increase steeply (AN), moderately (γ-BL), or negligibly (PC) at higher IL concentrations. This behavior was related to the different solvation patterns in the employed solvents. In BmimPF6-based systems, anionic diffusivities were followed via 31P nuclei and found to be higher than the corresponding cation values in IL-poor systems and lower in the IL-rich region. The inversion point of relative ionic diffusivities was found around equimolar composition and does not depend on the solvent. At this point, a distinct change in the ion-diffusion mechanism appears to take place.

11 pages; International audience; The combination of a neodymium borohydride, Nd(BH4)3(THF)3 (1) or Cp*Nd(BH4)2(THF)x (2), with MgnBuEt (BEM), affords an efficient and highly selective (up to 96.7% 1,4-trans) catalyst for butadiene polymerization. In the presence of excesses of Mg co-catalyst, polymer chain transfer takes place between neodymium and magnesium, and significant amounts of 1,2-units are observed. When considered for butadiene-styrene statistical copolymerization, the catalytic system based on 2 showed a good ability to produce poly[(1,4-trans-butadiene)-co-styrene)], with strong impact of the Mg/Nd ratio on the yield and on the copolymer microstructure, including the percentage of inserted styrene (up to 16.9 mol%). Whatever the co-monomers concentration the polybutadiene backbone remained 1,4-trans. The precise microstructure of the polymers and copolymers was thoroughly analyzed by means of high resolution NMR spectroscopy (900 MHz) and MALDI-ToF spectrometry.

International audience; The aim of this work was to develop the formation of multilayered coating incorporating a cyclodextrin polyelectrolyte onto a non-woven polyethylene terephthalate (PET) textile support in order to obtain reservoir and sustained release properties towards bioactive molecules. We optimized the multilayer assembly immobilization onto the PET surface according to the layer-by-layer (LbL) deposition process. After a pre-treatment of the textile support aiming to offer a sufficient ionic character to the surface, it was alternatively immersed into two polyelectrolytes aqueous solutions consisting of chitosan (CHT) as polycation on the one hand, and a _-cyclodextrin polymer (polyCTR- _CD) as polyanion on the other hand. In a second approach, a TBBA/polyCTR- _CD complex (4-tert-butylbenzoic acid, TBBA) was used in order to load the system with a drug model whose kinetics of release was assessed. Gravimetry, microscopy, OWLS, colorimetric titration, infrared and zetametry were used as characterization techniques. An effective deposition on the textile surface due to ionic interactions with alternation of up to 10 layers of each of both polyelectrolytes was clearly evidenced. However, we observed that layer formation occurred to a lesser extent when TBBA/polyCTR- _CD complex was applied instead of polyCTR- _CD alone. The release study showed that drug reservoir properties and release kinetics could be controlled by the number of layers in the system and that TBBA release was faster than the multilayered coating degradation.

Previous results obtained for the cis-polymerisation of isoprene with scandium half-sandwich complex Cp*Sc(BH4)2(THF) 1a were extended to its neodymium analog. The X-ray structure of the already reported neodymium monomer compound Cp*Nd(BH4)2(THF)21b is presented. Cp*Nd(BH4)2(THF)2/[CPh3][B(C6F5)4]/Al(iBu)3 catalytic system was found to be very active and stereoselective towards isoprene polymerisation, leading to highly 1,4-cis polyisoprene up to 92%. The effect on isoprene polymerisation of the addition of a NHC molecule to Cp*Ln(BH4)2(THF)n pre-catalyst (Cp* = η5-C5Me5, Ln = Sc, n = 1, 1a; Nd, n = 2, 1b; Sm, n = 2, 1c) or to a trisborohydride Ln(BH4)3(THF)n (Ln = Sc, n = 1.5, 2a; Nd, n = 3, 2b; Sm, n = 3, 2c) was also studied. Several NHC ligands were assessed: the classical [1-C{(NtBuCH)}2] (L1) and functional N-heterocyclic carbenes, two amino-tethered HNButCH2CH2[1-C{N(CHCH)NR}] (HL2-R) (R = tBu, Mes (Mes = 2,4,6-Me3-C6H2)) and the hydroxyl-tethered HOCMe2CH2[1-C{N(CHCH)NiPr}] (HL3). Neodymium-based complex (L2-tBu)Nd(BH4)2(THF)23 could be isolated and characterized. With some of the catalytic combinations tested, the introduction of the NHC ligand in the coordination sphere of the complex induces a switch of the stereoselectivity of the resulting polymer. Scandium complex 2a, which produces mainly 1,4-cis polyisoprene when associated to a borate activator and aluminum alkyl, leads to 1,4-trans polymer up to 94% regular when HL2-tBu carbene is added to the same reaction mixture. This result is the only example of highly trans-polyisoprene synthesized with a scandium based catalyst. Coordination of the carbene moiety to the rare earth centre is confirmed by NMR studies on paramagnetic neodymium pre-catalysts.

A textile polyester vascular graft was modified with cyclodextrins to obtain a new implant capable of releasing antibiotics (here ciprofloxacin, CFX) over prolonged time periods and thereby reducing the risk of post-operative infections. In this study, we compared samples modified with native and modified cyclodextrins, presenting different cavity sizes (β or γ cyclodextrins) and different substituent groups (hydroxypropyl and methyl). Drug release was measured in water, phosphate buffer pH 7.4 and blood plasma. The inclusion of CFX in the cyclodextrins cavities was observed in solution by two-dimensional (1)H NMR spectroscopy and confirmed by (1)F NMR measurements. Grafts modification with all cyclodextrins induced an increase of their sorption capacity towards CFX whose extent depended on the nature of the cyclodextrin: a 4-fold and 10-fold increase was observed in the cases of hydroxypropyl cyclodextrins and methylated β-cyclodextrin, respectively. Depending on the type of release medium and nature of CD, different CFX release kinetics were obtained. The discussion highlighted not only the role of the host guest complexation, but also that of the electrostatic interactions that occur between the anionic crosslinks of the cyclodextrins polymers, and CFX that presents a zwitterionic character. The microbiological assessment confirmed sustained CFX release in human plasma and demonstrated antibacterial efficiency of CD modified prostheses against Staphylococcus aureus and Escherichia coli for at least 24 h (compared to 4 h in the case of virgin grafts).

Through a case study, we will exemplify how ICT can be used in a collaborative way to constitute the foundations of intercultural projects in local and global communities. First, we present a local learning community based on the Fifth Dimension model where, adopting a collaborative model, each of its activities departed from the traditional teaching-learning form based on transmission. Collaboration mediated by ICT in local computer-supported learning communities, understood to be borderer zones that are not the exclusive property of any one specific cultural group, has the potential to generate genuine neo-cultures in which participants can share meanings and appropriate artefacts. Second, the same approach is adopted to analyse the dialogue established between educational researchers and technologists. Setting out with different goals, both groups engaged in a borderer activity involving the development of educational artefacts that could be accessed via the Internet. Common participation in those activities gave rise to a set of shared beliefs, knowledge, behaviours and customs, i.e. a network of meanings that crystallised into a common microculture.

A ferrocene-functionalised ureidopyrimidinone has been synthesised that can signal the solvent-induced tautomerism of the dimeric 4[1H]-pyrimidinone form to the monomeric 6[1H]-pyrimidinone form.

In parodontology, guided tissue regeneration (GTR) is a new technique to cure periodontal lesions. Where the association of the GTR with an antimicrobial agent does not yield optimal results, we used the properties of cyclodextrins (CDs) to improve the membrane used in RTG to control the release and to increase the quantity of antimicrobial agent stocked on the membrane. We successed in fixing 14%-wt of cyclodextrin polymer on polyvinylidene difluoride (PVDF) membranes thank to citric acid (CTR) as crosslinking agent. We studied the complexation of chlorhexidine diacetate (CHX), the antiseptic agent used in this study, with CDs in UV-spectrophotometry and ROESY NMR. We observed complexation of CHX by b, c, hydroxypropylated (HP) bCD. We studied the biological properties of the cyclodextrin polymer onto (PVDF) membranes and observed that the CDs-polymer is not harmful for the cells. Moreover it stimulates their growth with native CD. A kinetic of release of the CHX was performed. Raw membranes released all CHX stocked in few hours, whereas grafted membranes released more than tenfold this quantity during 60–80 days.

The purpose of this study was to develop a membrane for guided tissue regeneration applicable in periodontology that could release antimicrobial agent during the healing period. Our strategy consisted to graft beta-cyclodextrin (beta-CD), a molecule that is known to form inclusion complexes with a large variety of drugs, onto PVDF membranes. Grafting occurred by using citric acid that provoked a crosslinking reaction of beta-CD, and the resulting polymer was imprisoned into the porous structure of the PVDF membrane. The reaction produced a weight increase of the membrane, the range of which depended on the temperature and on the time of curing applied in the process. The biological behavior of the membranes evaluated by proliferation and vitality tests showed good proliferation and improved activity of L132 epithelial cells on the raw and on the grafted membranes. Doxycyclin (DOX) and chlorhexidine (CHX) were used as antimicrobial agents. Their inclusion into the beta-CD cavity in aqueous solutions was confirmed by NMR spectroscopy. After the impregnation of the membranes with DOX and CHX, their release was studied in vitro in batch type experiments and measured by UV spectrophotometry. Low amounts of DOX and CHX were delivered from the raw membranes within the first few hours of tests. Grafted membranes, however, delivered DOX and CHX in larger quantities within 24 h and 10 days respectively.