Diels-Alder reaction between indoles and cyclohexadienes photocatalyzed by a (thia)pyrylium salt

"Thiapyrylium salt 1 is an efficient photocatalyst in the Diels-Alder reaction between indoles (InHs) and 1,3-cyclohexadienes (CHDs). For instance, irradiation of deaerated dichloromethane solutions containing 1 (1 mM), indole (20 mM) and cyclohexadiene (40 mM), in the presence of an acylating agent, led to the Diels-Alder cycloadduct in 62% yield (endo:exo ratio of 1.8:1). Taking into account the very high intersystem crossing yield (Φisc = 0.97) of thiapyrylium salt 1, involvement of its triplet excited state in this Diels-Alder reaction has been studied using steadystate and time-resolved experiments; the results are compared with those previously obtained for pyrylium salts, which exhibit a considerable fluorescence quantum yield and are assumed to operate via electron transfer from the InH to their singlet excited state."Gonzalez Bejar, Maria, [email protected] ; Stiriba, Salah Eddine, [email protected] ; Perez Prieto, Julia, [email protected]

Synergistic assembly of hyperbranched polyethylenimine and fatty acids leading to unusual supramolecular nanocapsules

Self-assembly of hyperbranched polyethylenimine (PEI) and fatty acids leads to supramolecular inverted micellar structures that are able to irreversibly transfer water-soluble guest molecules into organic solvents.Perez Prieto, Julia, [email protected] ; Stiriba, Salah Eddine, [email protected]

Experimental Analysis of Gas–Liquid–Solid Three-Phase Flows in Horizontal Pipelines

The dynamics of three-phase flows involves phenomena of high complexity whose characterization is of great interest for different sectors of the worldwide industry. In order to move forward in the fundamental knowledge of the behavior of three-phase flows, new experimental data has been obtained in a facility specially designed for flow visualization and for measuring key parameters. These are (1) the flow regime, (2) the superficial velocities or rates of the individual phases; and (3) the frictional pressure loss. Flow visualization and pressure measurements are performed for two and three-phase flows in horizontal 30 mm inner diameter and 4.5 m long transparent acrylic pipes. A total of 134 flow conditions are analyzed and presented, including plug and slug flows in air–water two-phase flows and air–water-polypropylene (pellets) three-phase flows. For two-phase flows the transition from plug to slug flow agrees with the flow regime maps available in the literature. However, for three phase flows, a progressive displacement towards higher gas superficial velocities is found as the solid concentration is increased. The performance of a modified Lockhart–Martinelli correlation is tested for predicting frictional pressure gradient of three-phase flows with solid particles less dense than the liquid

Sustainable Construction of Heterocyclic 1,2,3-Triazoles by Strict Click [3+2] Cycloaddition Reactions Between Azides and Alkynes on Copper/Carbon in Water

1,4-Disubstituted-1,2,3-triazoles, considered as an important and useful class of heterocycles with potential applications in material science and biology, have been prepared in an efficient and selective manner by copper on carbon-catalyzed [3+2] cycloaddition reactions of azides and alkynes (CuAAC) in water under strict click chemistry conditions. Copper(I) catalysts heterogenized onto commercially activated carbon materials (Cu-CC) and on another carbon material produced from vegetable biomass using Argan nut shells (Cu-CANS) were found to be versatile catalytic sources for sustainable CuAAC. These copper on carbon supports were prepared and fully characterized by using two types of activated carbons that exhibit different porosity and specific surface. The delineation of the nature of the catalytic copper species and the role of the carbon support in the CuAAC were addressed. These heterogeneous copper on carbon catalysts were recovered and reused until ten catalytic runs without any noticeable loss of activity

Click synthesis, anticancer activity, and molecular docking investigation of some functional 1,2,3-triazole derivatives

1,2,3-triazole skeleton is a privileged building block for the discovery of new promising anticancer agents. In this report, new 1,4-disubstituted 1,2,3-triazoles with the bioisoster triazole moiety were straightforwardly prepared under copper-catalyzed azide-alkyne [3+2] cycloaddition reactions (CuAAC) regime using a variety of both functional organic azides and terminal alkynes. The resulting functional 1,4-disubstituted 1,2,3-triazole compounds were fully characterized and subsequently tested for their antiproliferative activity against four different cancer cell lines. The cytotoxicity tests carried out with these 1,2,3-triazole derivatives show average IC50 values ranging from 15 to 50 μM by comparison with the standard reference drug, namely doxorubicin. The phosphonate 1,2,3-triazole derivative was found to exhibit the best antiproliferative activity among the studied compounds against the HT-1080 cell lines. It was chosen to evaluate its mode of action in these cancer cell lines. The cell cycle study showed that the phosphonate derivative, compound 8, is the most active inhibitor of the cell cycle at the G0/G1 phase, inducing apoptosis independently of Caspase-3 and causing an increase in the mitochondrial membrane potential (ΔΨm) in the HT-1080 cell lines. Molecular docking studies of this phosphonate derivative into the MMP-2 and MMP-9 metalloproteinases receptors demonstrated the relevance of triazole scaffolds and the pendant phosphonate group in establishing -anion, -alkyl and hydrogen bonding type interactions with residual components in the active MMP pocket

Efficient ultraviolet-light energy dissipation by an aromatic ketone

Experimental evidence on the efficiency of 2,2'4,4'-tetramethoxybenzil for UV-light energy dissipation is provided. This non-phenolic aromatic ketone has a low energy triplet which quickly decays to the ketone ground state, thus avoiding the generation of undesirable reactive species.El Moncef, Abdelkarim, [email protected] ; Cuquerella Alabort, Maria Consuelo, [email protected] ; Zaballos Garcia, Elena, [email protected] ; Ramirez de Arellano Sanchez, Maria del Carmen, [email protected] ; Stiriba, Salah Eddine, [email protected] ; Perez Prieto, Julia, [email protected]

Synthesis and characterization of fourth generation polyester-based dendrimers with cationic amino acids-modified crown as promising water soluble biomedical devices

Dendrimers are nanostructured \u201carchitectural motifs\u201d which fascinate researchers fortheir several potentiality due to well\u2010tailored structure, symmetric tree\u2010like shape,and abilities in entrapping or binding hydrophilic or hydrophobic entities such asgenetic materials, drugs, and target molecules. Nowadays dendrimers inhabit thetop places among the materials suitable for biomedical applications as drug delivery,gene transfection, and imaging. In this work, we report the design and realization oftwo versatile successful procedures to decorate a fourth generation polyester\u2010baseddendrimer matrix with a mixture of four different amino acids. The hydrochloridedendrimers achieved after removal of protecting groups were characterized by acore\u2010shell structure. They harmonized a not charged hydrolysable inner matrixpotentially able to accommodate hydrophobic molecules and a cationic highlyhydrophilic crown conferred by biocompatible amino acids that provided very satis-factory buffer capacity and will allow easy host/guest electrostatic interactions.Their structures and peripheral composition were confirmed by NMR analysis andexperimental molecular weight computed by volumetric titration, while their buffercapacity was obtained by potentiometric titrations. Because in the inner matrix, theachieved hetero dendrimers do not present the high density of positive chargestypical of PAMAM, they ensure a lower level of toxicity. But thanks to the cationicperiphery, as preliminary investigations still in progress have already put in evidence, they were able to entrap not water soluble molecules by electrostatic inter-actions, with the result to increase their water solubility in a very satisfactory oramazing way. They therefore represent two new very promising devices for bio-medical applications

Dendritic Core-Shell Macromolecules Soluble in Supercritical Carbon Dioxide

International audienceSupercritical carbon dioxide has found strong interest as a reaction medium recently.1,2 As an alternative to organic solvents, compressed carbon dioxide is toxicologically harmless, nonflammable, inexpensive, and environmentally benign.3 Its accessible critical temperature and pressure (Tc ) 31 °C, Pc ) 7.38 MPa, Fc ) 0.468 g cm-3)4 and the possibility of tuning the solvent-specific properties between the ones of liquid and gas are very attractive