Synthesis and characterization of new thiazolidinones containing coumarin moieties and their antibacterial and antioxidant activities

New coumarin derivatives, namely (2-(4-methyl-2-oxo-2H-chromen-7-yloxy)-N-(4-oxo-2-phenylthiazolidin-3-yl)acetamide, N-(2-(3-methoxyphenyl)-4-oxothiazolidin-3-yl)-2-(4-methyl-2-oxo-2H-chromen-7-yloxy)acetamide, 2-(4-methyl-2-oxo-2H-chromen-7-yloxy)-N-(4-oxo-2-(2,3,4trimethoxyphenyl)thiazolidin-3-yl)acetamide and N-(2-(4-bromophenyl)-4-oxothiazolidin-3-yl)-2-(4-methyl-2-oxo-2H-chromen-7-yloxy)acetamide) were synthesized starting from 4-methyl-7-hydroxycoumarin. The structures of the obtained compounds were confirmed by analytical IR and NMR spectra to elucidate the different positions of protons and carbons and as well as theoretical studies (DFT/B3LYP). The new compounds were screened for antibacterial activity. Most of them are more active against E. coli S. aureus and B. subtilis than standard references.     

Synthesis and characterization of a poly[2,7-(9,9-dioctylfluorene-alt-2,7-fluorene/β-CD)] main chain polyrotaxane

Poly[2,7-(9,9-dioctylfluorene-alt-2,7-fluorene/β-CD)] main chain polyrotaxane was synthesized through organometallic Suzuki coupling by reacting β-cyclodextrin/2,7-dibromofluorene inclusion complex with 9,9-dioctylfluorene-2,7-bis(trimethyleneborate). The IR, NMR and elemental analysis data support the presence of β-cyclodextrin in the copolymer structure. No glass transition or melting phenomena were detected in DSC curves of the polyrotaxane on the heating run in the 50-250 ° range. As compared with the reference copolymer obtained in the absence of β-cyclodextrin, the rotaxane copolymer is more hygroscopic and soluble in polar/non-polar solvent mixtures. The expected modification of the optical properties of the fluorene copolymer with rotaxane architecture in the main chain was proved by fluorescence and UV-vis spectroscopy and consists in a blue-shifted emission.     

Towards near-infrared photosensitisation: a photosensitising hydrophilic non-peripherally octasulfanyl-substituted Zn phthalocyanine

A Zn(II) phthalocyanine substituted with eight hydroxylated sulfanyl moieties in non-peripheral positions was designed to exhibit properties desired for photodynamic therapy: hydrophilicity, isomeric purity and near-infrared absorption in addition to high singlet oxygen generation. Photophysical and photochemical studies proved to be promising.     

Synthesis of amphiphilic phenylazophenyl glycosides and a study of their liquid crystal properties

Several 4-(4'-N,N-didodecylaminophenylazo)phenyl 1,2-trans glycosides 5a-e with various carbohydrate heads (beta-D-gluco, beta-D-galacto, beta-lacto, beta-D-xylo, and alpha-D-manno) have been synthesized. The key step was the formation of phenyldiazonium tetrafluoroborates 2a-e from the per-O-acetylated 4-aminophenyl glycosides 1a-e. These salts were condensed with N,N-didodecylaniline under phase transfer conditions and the per-O-acetylated 4-(4'-N,N-didodecylaminophenylazo)phenyl 1,2-trans glycosides 4a-e were fully de-O-acetylated by the Zemplén method. The self-organizing liquid crystal properties of the compounds were investigated by a variety of techniques, including polarized light microscopy, differential scanning calorimetry, and X-ray diffraction. All but one of the materials exhibited smectic A, lamellar phases. Remarkably, the glucose derivative exhibited a rectangular disordered columnar phase. This result has implications with respect to the induced curvature created by the recognition processes of the glucose headgroup relative to the other sugar moieties and to the prevalence of various glycolipids in cell membranes     

Preparation of amphiphilic glycerol-substituted zinc phthalocyanines using copper-free Sonogashira cross-coupling in aqueous medium

Palladium-catalyzed copper-free Sonogashira cross-coupling reactions were performed on a protected and unprotected monoiodotriglycerol substituted Zn(II) phthalocyanine with various alkynes in organic and aqueous medium. From the silyl protected alkyne derivative, a protected homo coupled dimeric product was also prepared using Glaser coupling. All products were purified by reverse phase HPLC and the assigned structures were confirmed by mass and UV-vis spectroscopy.     

Large deviations for Brownian motion in a random scenery

We prove large deviations principles in large time, for the Brownian occupation time in random scenery . The random field is constant on the elements of a partition of ^d into unit cubes. These random constants, say consist of i.i.d. bounded variables, independent of the Brownian motion {B_s,s0}. This model is a time-continuous version of Kesten and Spitzer's random walk in random scenery. We prove large deviations principles in ``quenched' and ``annealed' settings.Mathematics Subject Classification (2000):60F10, 60J55, 60K37     

Respiratory adaptations to the deep-sea hydrothermal vent environment: the case of Segonzacia mesatlantica, a crab from the Mid-Atlantic Ridge

Segonzacia mesatlantica (Crustacea; Decapoda; Brachyura) is the only endemic crab species known from the Mid-Atlantic Ridge (MAR) hydrothermal vents. Known from all explored sites in the Atlantic, its wide distribution makes this species a model to study physiological adaptation, and specifically respiratory strategies. Native haemocyanin (Hc) comprises four non-covalent associations in equilibrium formed by monomers, hexamers, dodecamers and octadecamers made up of approximately 75 kDa polypeptide chains. Four different amino acid chains are observed with a molecular mass ranging from 75,234 to 75,972 Da. Experiments carried-out under pressure suggested that the percentage of monomer increased in the haemolymph under hypoxic condition. We have also observed a shift of the proportion of the two dodecamer series, suggesting a rapid modification of the Hc phenotype between hypoxic and hyperoxic conditions. Native Hc possesses a high oxygen affinity ( P50 = 2.2 Torr at 15 degrees C and pH 7.5), a large Bohr effect (Deltalog P50 / DeltapH approximately -2.7) and a slightly reverse temperature effect (DeltaH = +17.19 kJ mol(-1). The composition of Segonzacia haemolymph is similar to that of other littoral species except for the large enrichment in free copper and zinc. As for other species from hydrothermal vent sites, Segonzacia haemolymph possesses a higher buffer capacity than littoral species. Moreover, species from the hydrothermal vent decapods from Pacific hydrothermal vent that encounter higher CO2 content in their environment have a higher buffer capacity than Atlantic vent species. The results presented are discussed in relation with the physico-chemical characteristics of the hydrothermal vent environment.     

Synthesis of new artemisinin-derived dimers by self-cross-metathesis reaction

[reaction: see text] New artemisinin-derived dimers, fluorinated or not, have been prepared by a self-cross metathesis reaction in the presence of first- or second-generation ruthenium catalysts without degradation of the endoperoxide bridge and with a good E/Z selectivity (up to 100:0).     

Synthesis of a new polymer surface bearing grafted azo polymer chains

Azobenzene, a photosensitive chromophore that undergoes photoinduced and thermal cis–trans isomerization, can be applied in a nonlinear optical field. {4′‐[(Hydroxy)ethyl]amino}‐4‐nitroazobenzene (disperse red 1) corresponds to one of these azo compounds, which can be grafted to a polymer chain as a part of the main chain, as a dangling group, or onto the polymer surface. In the last case, disperse red 1 is transformed into an acrylic monomer and then grafted onto a polypropylene surface modified with a cold carbon dioxide‐plasma treatment. A method is proposed for quantifying the radicals formed during the plasma treatment and, consequently, for optimizing the grafting reaction. The best conditions (the nature of the solvent, temperature, monomer concentration, and duration) are given. Both IR and Raman spectroscopies were used as efficient techniques for grafting characterization. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3052–3061, 2001