Synthesis and physico-chemical studies of glycine betaine derivatives

Poster (2012, October 11)

Design of new surfactants is of considerable interest in order to obtain materials with specific physico-chemical properties for targeted applications. Among them, quaternary ammonium surfactants are ... [more ▼]

Design of new surfactants is of considerable interest in order to obtain materials with specific physico-chemical properties for targeted applications. Among them, quaternary ammonium surfactants are widely employed in pharmaceutical and cosmetic industries. Unfortunately, as a consequence of their widespread use and strong resistance to biodegradation, those chemical surfactants may persist in wastewater treatment systems at relatively high concentrations and can cause a disturbance of the ecological equilibrium. In this context, glycine betaine based surfactants are of increasing interest today thanks to their higher biodegradability and low environmental impact. For example, alkylbetaines and alkylamidobetaines are produced on the industrial scale and are used as amphoteric surfactants less irritating compared to sodium dodecylsulfate (SDS) in cosmetics. In this study, new surface-active agents based on glycine betaine and issued from the green chemistry are synthesized. Very simple synthetic methodologies led to different betaine derivatives (esters, thioesters, amides). Their physico-chemical properties are investigated in order to give insights about the key parameters to take into account for the formulation of betaine derived compound preparations for cosmetic or pharmaceutical purposes. [less ▲]

Synthesis and potential of new functional aliphatic polyesters

Doctoral thesis (2002)

Synthesis and preliminary characterization of model liquid crystalline ionomers

in Macromolecules (1996), 29(10), 3376-3383

Model liquid crystalline ionomers have been synthesized that consist of low molecular weight linear chains selectively end-capped at one or both end(s) with an ionic mesogenic group. ω- and α,ω ... [more ▼]

Model liquid crystalline ionomers have been synthesized that consist of low molecular weight linear chains selectively end-capped at one or both end(s) with an ionic mesogenic group. ω- and α,ω-carboxylato and sulfonato polystyrene chains have been prepared by living anionic polymerization and associated with mesogenic counterions, the structure of which is a rigid azobenzene moiety attached to a quaternary ammonium halide through a flexible spacer. The thermotropic behavior of the liquid crystalline halato(semi)telechelic polymers (LC H(S)TP's) has been studied by differential scanning calorimetry and optical microscopy. Some of them show smectic mesophases in a large temperature range. Actually, the liquid crystalline properties of the LC H(S)TP's depend on the molecular weight and the nature of the ionic end groups. A model, based on a crystal close packing approach, shows that the bulkiness of the sulfonato end groups can prevent the formation of smectic mesophases. The supramolecular organization of the LC H(S)TP's has also been studied by small angle neutron scattering, which agrees with a microphase separation between the polymer chains and the mesogenic counterions. [less ▲]

Synthesis and properties of poly[isobornyl methacrylate (IBMA)-b-butadiene (BD)-b-IBMA] copolymers : new thermoplastic elastomers of a large service temperature range

in Macromolecules (1996), 29(16), 7316-7332

Anionic polymerization of isobornyl methacrylate (IBMA) has been studied in THF and toluene in a temperature range from −78 to +40 °C by using (1,1-diphenyl-3,3-dimethylbutyl)lithium (DDBLi) as an ... [more ▼]

Anionic polymerization of isobornyl methacrylate (IBMA) has been studied in THF and toluene in a temperature range from −78 to +40 °C by using (1,1-diphenyl-3,3-dimethylbutyl)lithium (DDBLi) as an initiator in the presence of LiCl or not. Effect of solvent and polymerization temperature on tacticity has been studied. The reactivity of IBMA is comparable to tert-butyl methacrylate (tBMA), and polymers of a very narrow molecular weight distribution (<1.10) have been synthesized at room temperature, in THF, in the presence of LiCl. The Tg of PIBMA is found to vary from 170 to 206 °C with chain tacticity. Poly(isobornyl methacrylate) (PIBMA)−polybutadiene (PBD)−PIBMA triblock copolymers have been synthesized by using the m-diisopropenylbenzene (m-DIB)/tert-butyllithium (t-BuLi) diadduct as an initiator. The PBD midblock has been prepared in a cyclohexane/diethyl ether (100/6, v/v) mixture at room temperature. THF has been added [cyclohexane/diethyl ether/THF (100/6/100, v/v/v)] before the IBMA polymerization takes place at either −78 or +25 °C. Triblock copolymers of a very narrow molecular weight distribution (1.10) have been synthesized even at 25 °C, and no gel formation has been observed. These new triblock copolymers exhibit high tensile strength (30 MPa), high ultimate elongation (1000%), and high upper service temperature (160 °C). [less ▲]

Synthesis and radioligand binding studies of bis-(8-isopropylisoquinolinium) derivatives as ligands for apamin-sensitive sites on cloned SK2 and SK3 channels

in Bioorganic & Medicinal Chemistry Letters (2011), 21(22), 6756-6759

A structure-activity relationship study of N-methyl-laudanosine, a SK channel blocker, has indicated that the 6,7-dimethoxy group could be successfully replaced by a hydrophobic moiety such as an ... [more ▼]

A structure-activity relationship study of N-methyl-laudanosine, a SK channel blocker, has indicated that the 6,7-dimethoxy group could be successfully replaced by a hydrophobic moiety such as an isopropyl substituent in position 8 of the isoquinoline ring. In the present study, bis-(8-isopropyl-isoquinolinium) derivatives (2a-e) were synthesized and tested for their affinity for cloned SK2 and SK3 channels in comparison with their 6,7-dimethoxy analogues (4a-f). Several ligands were investigated, both in flexible (propyl, butyl and pentyl) and rigid (m- or p-xylyl) series, the m-xylyl derivative (2d) having the best profile in terms of affinity and selectivity for SK3/SK2 channels. Molecular studies showed that the optimal conformation of compound 2d fits well with our SK pharmacophore model. [less ▲]

Synthesis and radioligand binding studies of C-5- and C-8-substituted 1-(3,4-dimethoxybenzyl)-2,2-dimethyl-1,2,3,4-tetrahydroisoquinoliniums as SK channel blockers related to N-methyl-laudanosine and N-methyl-noscapine

in Journal of Medicinal Chemistry (2005), 48(15), 4972-4982

The synthesis and the 125 I-apamin binding studies of original C-5- and C-8-substituted 143,4-dimethoxy-benzyl)-2,2-dimethyl-1,2,3,4-tetrahydroisoquinoliniums and 1-(3,4-dimethoxy-benzyl)-6,6-dimethyl-4,5 ... [more ▼]

The synthesis and the 125 I-apamin binding studies of original C-5- and C-8-substituted 143,4-dimethoxy-benzyl)-2,2-dimethyl-1,2,3,4-tetrahydroisoquinoliniums and 1-(3,4-dimethoxy-benzyl)-6,6-dimethyl-4,5,6,7-tetrahydrothieno[2,3-c]pyridiniums were performed in order to find a reversible and selective SK channel blocker structurally related to N-methyl-laudanosine and N-methyl-noscapine. A bulky alkyl substituent in the C-8 position of the tetrahydroisoquinoline produces a clear increase in the affinity for the apamin sensitive binding sites. The presence of an electron-withdrawing group in the C-5 and C-8 positions is not a suitable substitution for the affinity of drugs structurally related to N-methyl-laudanosine. Thiophenic analogues and 8-methoxy derivatives possess a poor affinity for the apamin sensitive binding sites. Electrophysiological studies performed with the most effective compound showed a blockade of the apamin sensitive afterhyperpolarization in rat dopaminergic neurons. [less ▲]

Synthesis and ring-opening metathesis polymerization of eight-membered unsaturated lactams and related monomers

in Journal of Molecular Catalysis A-Chemical (2002), 190(1-févr Sp. Iss. SI), 109-116

Novel eight-membered ring unsaturated lactams were synthesized and tested as monomers for the ruthenium-catalyzed ring-opening metathesis polymerization (ROMP). The reaction of a N-protected cyclic ... [more ▼]

Novel eight-membered ring unsaturated lactams were synthesized and tested as monomers for the ruthenium-catalyzed ring-opening metathesis polymerization (ROMP). The reaction of a N-protected cyclic alkeneamine was also investigated. The Grubbs' benzylidene complexes RuCl2(=CHPh)(PCy3)(2) or RUCl2(=CHPh)(PCy3)(IMesH(2)) and selected ruthenium-arene species bearing either phosphine or stable Arduengo-type N-heterocyclic carbene ligands served as catalyst precursors. In most cases, isomerization of the starting materials took place and only 1-benzyl-1-aza-2-ketocyclooct-5-ene afforded a polymeric product. This polyamide was characterized by numerous analytical techniques. (C) 2002 Elsevier Science B.V All rights reserved. [less ▲]

Synthesis and stabilization of colloids for optical and magnetic detections

Doctoral thesis (2008)

The development of nano-sized particles is motivated by their optical, electronic and magnetic behavior related to quantum confinement resulting from the nanometric size. To prevent aggregation in ... [more ▼]

The development of nano-sized particles is motivated by their optical, electronic and magnetic behavior related to quantum confinement resulting from the nanometric size. To prevent aggregation in solution, the nanoparticles are covered with stabilizing molecules. The aim of this thesis is to develop a new generation of functional copolymers with different architectures to improve the stability of various synthesized NPs. Two types of nanoparticles are considered, gold NPs for the optical properties and iron oxide NPs for the magnetic properties. The copolymers considered in this study are synthesized following a controlled radical polymerization process, i.e. Reversible Addition - Fragmentation Chain Transfer (RAFT) and confer novel properties to the coated nanoparticles. Stealth NPs are obtained when they are covered by the poly(ethylene oxide), and thermosensitive NPs when they are stabilized by the poly (N-isopropyl acrylamide). These properties have been exploited in applications in the biomedical field. Another challenge in this work is the synthesis and functionalization of the surface of carbon NPs, and thus carbon nano-capsules were synthesized by graphitization of poly (acrylic acid)-poly (acrylonitrile) micelles and carbon nanotubes have been decorated by magnetite NPs allowing their orientation in a magnetic field. [less ▲]

Synthesis and study of wetting and swelling behaviour of PLA-PEO-PLA and PCL-PEO-PCL copolymers

Poster (2009, March 01)

Synthesis and thermal properties of linear amphiphilic diblock copolymers of L-lactide and 2-dimethylaminoethyl methacrylate

in Macromolecules (2011), 44(13), 5209-5217

A well-defined series of nine poly(l-lactide)-b-(2-dimethylaminoethyl methacrylate) (PLLA-b-PDMAEMA) linear diblock copolymers with low polydispersity were prepared by ring-opening polymerization of LLA ... [more ▼]

A well-defined series of nine poly(l-lactide)-b-(2-dimethylaminoethyl methacrylate) (PLLA-b-PDMAEMA) linear diblock copolymers with low polydispersity were prepared by ring-opening polymerization of LLA using 4-isopropylbenzyl alcohol and tin octoate as the initiating system, conversion of the OH-terminated PLLA into Br-terminated macroinitiators (5, 13, and 19 kg/mol), followed by atom transfer radical polymerization of DMAEMA (to obtain one-half, equal, and twice the molecular weight of each PLLA block). Compositional analysis and molecular weight characterization were done using NMR, SEC–LS, TGA, polarimetry, and PDMAEMA quaternization/precipitation to test for residual PLLA homopolymer. DSC investigations indicate that low molecular weight amorphous PLLA or PDMAEMA blocks (less than or equal to ca. 5000 g/mol) are miscible in the second block. Compared to the parent PLLA homopolymers, PLLA crystallization in the block copolymers is significantly retarded, whereas the degree of crystallinity is only mildly affected and melting points are reduced only for the low molecular weight miscible blocks. [less ▲]