Sugar-derived tricatenar catanionic surfactant: self-assembly and aggregation behavior in the cationic-rich side of the system

The aggregation behavior of the cationic-rich side of a sugar-based tricatenar catanionic mixture was investigated in water, and it was shown that the excess of cationic sugar-based surfactant enhanced vesicle stability as well as encapsulation properties. Moreover, when the system was diluted, the vesicular solution collapsed into a lamellar phase, whereas, when it was concentrated, no major impact on the shape and stability of the aggregates was observed. We also showed that both an increase in temperature and the addition of salt induced reversible vesicle aggregation, which appeared to be salt-specific, following the direct order of the Hofmeister series. A proper adjustment of these parameters should then enable better control of the shape, stability, and even encapsulation ability of the aggregates formed by these tricatenar cationic/anionic mixtures.     

Nickel-Catalyzed Electrochemical Synthesis of (Hetero)Aryl Trifluoromethyl Selenides

A convenient and efficient approach for the construction of aryl trifluoromethyl selenoethers from aryl iodides under mild conditions is reported. Electrochemical activation of stable and inexpensive NiBr₂bipy (bipy – bipyridine) complex instead of labile Ni(COD)₂ (COD – cyclooctadiene) catalyst. [NMe₄][SeCF₃] is employed as shelf-stable source of SeCF₃ fragment. The reaction tolerates a wide range of substrates, including modification of drug-like molecules. Cyclic voltammetry studies allow insight into the reaction mechanism.     

Facile control of silica nanoparticles using a novel solvent varying method for the fabrication of artificial opal photonic crystals

In this work, the Stöber process was applied to produce uniform silica nanoparticles (SNPs) in the meso-scale size range. The novel aspect of this work was to control the produced silica particle size by only varying the volume of the solvent ethanol used, whilst fixing the other reaction conditions. Using this one-step Stöber-based solvent varying (SV) method, seven batches of SNPs with target diameters ranging from 70 to 400 nm were repeatedly reproduced, and the size distribution in terms of the polydispersity index (PDI) was well maintained (within 0.1). An exponential equation was used to fit the relationship between the particle diameter and ethanol volume. This equation allows the prediction of the amount of ethanol required in order to produce particles of any target diameter within this size range. In addition, it was found that the reaction was completed in approximately 2 h for all batches regardless of the volume of ethanol. Structurally coloured artificial opal photonic crystals (PCs) were fabricated from the prepared SNPs by self-assembly under gravity sedimentation.

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Design of original bioactive formulations based on sugar-surfactant/non-steroidal anti-inflammatory catanionic self-assemblies: a new way of dermal drug delivery

A new kind of catanionic assembly was developed that associates a sugar-based surfactant with a non-steroidal anti-inflammatory drug (NSAID). Three different assemblies using indomethacin, ibuprofen and ketoprofen as NSAIDs were easily obtained in water by an acid-base reaction. These assemblies formed new amphiphilic entities because of electrostatic and hydrophobic effects in water and led to the spontaneous formation of vesicles. These catanionic vesicles were then tested as potential NSAID delivery systems for dermatological application. The anti-inflammatory activity was evaluated in vivo, and this study clearly showed an improved therapeutic effect for NSAIDs that were formulated as catanionic vesicles. These vesicles ensured a slower diffusion of the NSAID through the skin. This release probably increased the time of retention of the NSAID in the targeted strata of the skin. Thus, the present study suggests that this catanionic bioactive formulation could be a promising dermal delivery system for NSAIDs in the course of skin inflammation treatment.     

Plant-Derived Pesticides as an Alternative to Pest Management and Sustainable Agricultural Production: Prospects,Applications and Challenges

Pests and diseases are responsible for most of the losses related to agricultural crops, either in the field or in storage. Moreover, due to indiscriminate use of synthetic pesticides over the years, several issues have come along, such as pest resistance and contamination of important planet sources, such as water, air and soil. Therefore, in order to improve efficiency of crop production and reduce food crisis in a sustainable manner, while preserving consumer’s health, plant-derived pesticides may be a green alternative to synthetic ones. They are cheap, biodegradable, ecofriendly and act by several mechanisms of action in a more specific way, suggesting that they are less of a hazard to humans and the environment. Natural plant products with bioactivity toward insects include several classes of molecules, for example: terpenes, flavonoids, alkaloids, polyphenols, cyanogenic glucosides, quinones, amides, aldehydes, thiophenes, amino acids, saccharides and polyketides (which is not an exhaustive list of insecticidal substances). In general, those compounds have important ecological activities in nature, such as: antifeedant, attractant, nematicide, fungicide, repellent, insecticide, insect growth regulator and allelopathic agents, acting as a promising source for novel pest control agents or biopesticides. However, several factors appear to limit their commercialization. In this critical review, a compilation of plant-derived metabolites, along with their corresponding toxicology and mechanisms of action, will be approached, as well as the different strategies developed in order to meet the required commercial standards through more efficient methods.     

Enantioselective Linchpin Catalysis by SOMO Catalysis: An Approach to the Asymmetric α‐Chlorination of Aldehydes and Terminal Epoxide Formation

Time for SOme MOre : For the first time SOMO (singly occupied molecular orbital) activation has been exploited to allow a new approach to the α‐chlorination of aldehydes. This transformation can be readily implemented as part of a linchpin catalysis approach to the enantioselective production of terminal epoxides.

     

Extension groups between simple Mackey functors

In order to better understand the structure of indecomposable projective Mackey functors, we study extension groups of degree 1 between simple Mackey functors. We explicitly determine these groups between simple functors indexed by distinct normal subgroups. We next study the conditions under which it is possible to restrict ourselves to that case, and we give methods for calculating extension groups between simple Mackey functors which are not indexed by normal subgroups. We then focus on the case where the simple Mackey functors are indexed by the same subgroup. In this case, the corresponding extension group can be embedded in an extension group between modules over a group algebra, and we describe the image of this embedding. In particular, we determine all extension groups between simple Mackey functors for a p-group and for a group that has a normal p-Sylow subgroup. Finally, we compute higher extension groups between simple Mackey functors for a group that has a p-Sylow subgroup of order p.     

Improved tandem mass spectrometric characterization of 3-nitrotyrosine sites in peptides

Nitrated tyrosines are easily converted into their aminotyrosine equivalents by a reduction step. We here show that this conversion can be exploited to readily discern 3-aminotyrosine peptides in a background of non-nitrated peptides. Furthermore, aminotyrosine peptides are more stable in single mass spectrometry (MS) mode rendering peptide mass maps easier to interpret. One significant caveat of both 3-nitrotyrosine and 3-aminotyrosine peptides is their lack of efficient fragmentation upon collision-induced dissociation (CID) which, in the case of the latter peptides, also produces unexpected, deviating isotopic patterns of fragment ions containing the aminotyrosine residue. The net result is that sequence database searching becomes daunting as the correct peptide is frequently missed since insufficient and/or inaccurate peptide fragments are used. We show that a simple acetylation step, blocking all amines (including aminotyrosine), produces peptides that undergo extensive backbone fragmentation by CID and are thus easily identifiable in databases. Our procedure is additionally illustrated by doubling the number of nitration events mapped in tetranitromethane-nitrated bovine serum albumin (BSA) as compared to a direct analysis of the nitrated peptides using the same amount of material. In conclusion, we here illustrate that this two-step process, heme-mediated reduction and acetylation, can be used for more efficient characterization of protein-bound nitrated tyrosines.     

On the role of the bridging dicyanamidobenzene ligand in a new binuclear ruthenium complex: [{Ru(tpy)(thd)}2(mu-dicyd)][PF6] with tpy = 2,2':6',2' '-terpyridine and thd = 2,2,6,6-tetramethyl-3,5-heptanedione

The dicyanamidobenzene-bridge diruthenium complex [{Ru(tpy)(thd)}(2)(mu-dicyd)][PF(6)] ([3][PF(6)]) (dicyd = 1,4-dicyanamidobenzene, tpy = 2,2':6',2' '-terpyridine, thd = 2,2,6,6-tetramethyl-3,5-heptanedione) and its mononuclear counterpart [Ru(tpy)(thd)(Ipcyd)] (2) [Ipcyd = 4-iodophenylcyanamide anion (Ipcyd(-))] were synthesized and fully characterized. Cyclic voltammetry of 3 showed the presence of four reversible one-electron redox couples. UV-vis-NIR spectroelectrochemistry and EPR spectroscopy of the electrogenerated paramagnetic intermediates were used to ascertain the oxidation-state distribution. The stable starting dinuclear complex 3(+) is found to be a ligand-centered anion radical as shown by EPR spectroscopy, magnetic susceptibility measurements, and DFT calculations. Oxidation of 3(+) to 3(2+) led to an EPR silent system due to substantial intramolecular antiferromagnetic interaction of the electron spins carried by the low spin ruthenium(III) atom and the bridging anion radical dicyanamido (dicyd(*)(-)), an observation which was supported by UV-vis-NIR, X-ray structure, and DFT calculations. Complex 3(3+) presented an EPR spectra consistent with a total effective spin S = (1)/(2) issued from an antiferromagnetic interaction of electron spins carried by two low spin ruthenium(III) atoms and the bridging anion radical dicyd(*)(-) in accordance with UV-vis-NIR. This study shows that the dicyanamidobenzene bridging ligand has indubitably a noninnocent behavior.