Supramolecular behavior of fluorous polyglycerol dendrons and polyglycerol dendrimers with perfluorinated shells in water

Zieringer, Maximilian,Wyszogrodzka, Monika,Biskup, Karina,Haag, Rainer

, p. 402 - 406 (2012)

In this article, we describe the synthesis of a perfluoro-tagged polyglycerol dendron and its aggregation behavior in the presence of polyglycerol dendrimers with perfluorinated shells in water. The perfluoro-alkyl-perfluoro-alkyl interactions between the perfluorinated shells of the dendrimers and the perfluorinated tags of the dendrons lead to highly stable supramolecular architectures, due to self-assembly of the perfluorinated moieties. Furthermore, we show that the size of the resulting supramolecular complexes can be tuned by simple variation of the dendrimer-dendron ratio. Complexes at various ratios are characterized by optical microscopy, DLS, and TEM. In general, the results presented herein demonstrate that perfluoro-alkyl-perfluoro-alkyl interactions are applicable for the formation of stable supramolecular structures in water and thus provide a new tool for the design of supramolecular architectures in addition to traditional non-covalent interactions.

Bentley,Mc Crae

, p. 2082 (1970)

A Kinetic Investigation of Triacetin Methanolysis and Assessment of the Stability of a Sulfated Zirconium Oxide Catalyst

Temóteo, Rafael L.,da Silva, Marcio J.,de ávila Rodrigues, Fabio,da Silva, Wagner F.,de Jesus Silva, Deusanilde,Oliveira, Cesar M.

, p. 865 - 874 (2018)

In this work, the activity and stability of a sulfated zirconium catalyst in transesterification reactions of triacetin, a model molecule, were investigated. This catalyst has Lewis and Br?nsted acid sites and has shown to be highly active in reactions converting triacetin into methyl esters. This catalyst was synthesized using the impregnation method, and systematically characterized using the techniques of x-rays diffraction (XRD), scanning electron microscopy, Fourier transform-infrared spectroscopy (FT-IR), Brunauer, Emmett, and Teller, and thermal gravimetry analysis (TGA). Kinetic studies were carried out to determine the activation energy as well as the reaction order. The effects of the main reaction parameters, such as temperature, the molar ratio, and the catalyst content, were evaluated. The reuse and possible leaching of the catalyst were also investigated. The highest efficiency (ca. 99% of methyl esters) was achieved in the sulfated zirconium oxide-catalyzed transesterification reaction.

Non-ionic dendronized multiamphiphilic polymers as nanocarriers for biomedical applications

Gupta, Shilpi,Schade, Boris,Kumar, Sumit,Boettcher, Christoph,Sharma, Sunil K.,Haag, Rainer

, p. 894 - 904 (2013)

A new class of non-ionic dendronized multiamphiphilic polymers is prepared from a biodegradable (AB)n-type diblock polymer synthesized from 2-azido-1,3-propanediol (azido glycerol) and polyethylene glycol (PEG)-600 diethylester using Novozym-43

NO donors. Part 18: Bioactive metabolites of GTN and PETN-Synthesis and vasorelaxant properties

Lange, Kathrin,Koenig, Andreas,Roegler, Carolin,Seeling, Andreas,Lehmann, Jochen

, p. 3141 - 3144 (2009)

The vasodilators glyceryl trinitrate (GTN) and pentaerythrityl tetranitrate (PETN) are supposed to be degraded in vivo to the lower nitrates PETriN, PEDN, PEMN, 1,2-GDN, 1,3-GDN, 1-GMN, and 2-GMN. We synthesized these bioactive metabolites as reference compounds for pharmacokinetic studies. The use of HPLC-methods for monitoring the stepwise reduction of PETN to lower nitrates and the syntheses of the glyceryl dinitrates proved advantageous. Furthermore, we measured the vasorelaxant properties of all metabolites by performing organ bath experiments with porcine pulmonary arteries. In general, the vasodilator potency increases with the number of nitrate moieties in the compound.

Transesterification of triacetin and castor oil with methanol catalyzed by supported polyaniline-sulfate. A role of polymer morphology

Drelinkiewicz,Kalemba-Jaje,Lalik,Zi?ba,Mucha,Konyushenko,Stejskal

, p. 92 - 106 (2013)

Polyaniline-sulfate deposited on three different carriers was studied for transesterification of triacetin and castor oil with methanol at mild reaction conditions (temperature of 55 °C). Multi-wall carbon nanotubes (CNT), carbon and silica were coated with polyaniline sulfate (ca. 20 wt%) during polymerization of aniline. Because of different textural and hydrophobic properties of the carriers, the polymer coatings of various morphologies were obtained as evidenced by the electron microscopy technique. A uniform coating of CNT with polymer resulted in the most extended polymer structure. Nanorods of polymer forming branched dendritic structures appeared in the other two carbon and silica carriers. The acid capacity and the strength of acid sites were similar in all studied catalysts. All the samples were found to be active solid acid catalysts in methanolysis of both studied triglycerides and CNT-coated polyaniline sulfate exhibited the highest activity. The course of reaction during methanolysis of triacetin on CNT-containing catalyst was similar to that in the presence of soluble sulfuric acid. On the other hand, a partial blockage of active sites was observed in carbon and silica coated with polyaniline sulfate. A blockage effect was ascribed to strong interaction of acid sites with more polar reagents among them diacetin and glycerol. These interactions were facilitated by aggregated fibriral morphology of the polymer coating resulting in locally high density of acid sites.

4'-ETHYNYL-2'-DEOXYADENOSINE DERIVATIVES AND THEIR USE IN HIV THERAPY

-

Page/Page column 71, (2021/03/05)

The invention relates to compounds of Formulae (I)-(II), salts thereof, pharmaceutical compositions thereof, as well as methods of treating or preventing HIV in subjects.

Biodiesel Glycerin Valorization into Oxygenated Fuel Additives

Catarino, Mónica,Gomes Fonseca, Frederico,Gomes, Jo?o,Soares Dias, Ana Paula

, (2021/05/26)

Current industrial methods of biodiesel production lead to an excess of crude glycerin which requires costly purification before commercialization. Production of oxygenated fuel additives is a potential route for glycerin valorization. Glycerin acetylation was carried out over heterogeneous acid catalysts (15%, glycerol weight basis) using glacial acetic acid (molar ratio = 9). The catalysts, containing different amounts of phosphate species (P/Si from 10 to 20 atomic ratio), were prepared by wet impregnation of commercial silica with aqueous solutions of diammonium phosphate and ortho-phosphoric acid. X-ray diffraction patterns of calcined solids presented amorphous patterns like raw silica. The prepared catalysts presented, at 120?°C, glycerol conversion higher than 89.5% after 1?h of reaction, been diacetin the major product, with triacetin selectivities lower than 26.1%. Diacetin selectivity was found to be almost invariant with catalyst acidity thus underlining the relevance of catalyst porosity due to the large acetins molecules sizes. The slow rate of triacetin diffusion in narrow pores of catalyst might be responsible for the relatively low yield obtained. Surface phosphate species showed a slow rate of leaching in the reaction medium showing high catalyst stability. Graphical Abstract: [Figure not available: see fulltext.]