Search results for "Organo"
showing 10 items of 1460 documents
Exceptional affinity of nanostructured organic-inorganic hybrid materials towards dioxygen: confinement effect of copper complexes
2007
We report the exceptional reactivity towards dioxygen of a nanostructured organic-inorganic hybrid material due to the confinement of copper cyclam within a silica matrix. The key step is the metalation reaction of the ligand, which can occur before or after xerogel formation through the sol-gel process. The incorporation of a Cu(II) center into the material after xerogel formation leads to a bridged Cu(I)/Cu(II) mixed-valence dinuclear species. This complex exhibits a very high affinity towards dioxygen, attributable to auto-organization of the active species in the solid. The remarkable properties of these copper complexes in the silica matrix demonstrate a high cooperative effect for O(2…
Organocatalytic Enantioselective Aminoalkylation of 5‐Aminopyrazole Derivatives with Cyclic Imines
2020
The first enantioselective alkylation of 5‐aminopyrazoles is described with good results. The organocatalytic alkylation of 5‐aminopyrazoles have been accomplished using benzoxathiazine 2,2‐dioxides as electrophiles and a bifunctional squaramide organocatalyst.
Enzyme-Controlled Nanodevice for Acetylcholine-Triggered Cargo Delivery Based on Janus Au–Mesoporous Silica Nanoparticles
2017
[EN] This work reports a new gated nanodevice for acetylcholine-triggered cargo delivery. We prepared and characterized Janus Au-mesoporous silica nanoparticles functionalized with acetylcholinesterase on the Au face and with supramolecular b-cyclodextrin: benzimidazole inclusion complexes as caps on the mesoporous silica face. The nanodevice is able to selectively deliver the cargo in the presence of acetylcholine via enzyme-mediated acetylcholine hydrolysis, locally lowering the pH and opening the supramolecular gate. Given the key role played by ACh and its relation with Parkinson's disease and other nervous system diseases, we believe that these findings could help design new therapeuti…
An organogold compound as potential antimicrobial agent against drug resistant bacteria: Initial mechanistic insights
2021
Abstract The rise of antimicrobial resistance has necessitated novel strategies to efficiently combat pathogenic bacteria. Metal‐based compounds have been proven as a possible alternative to classical organic drugs. Here, we have assessed the antibacterial activity of seven gold complexes of different families. One compound, a cyclometalated Au(III) C^N complex, showed activity against Gram‐positive bacteria, including multi‐drug resistant clinical strains. The mechanism of action of this compound was studied in Bacillus subtilis. Overall, the studies point towards a complex mode of antibacterial action, which does not include induction of oxidative stress or cell membrane damage. A number …
In vitro morphogenesis from excised leaf explants of Digitalis obscura L.
1984
The morphogenic capacity of Digitalis obscura leaf explants cultured in vitro has been studied, noting factors promoting the differentiation of roots, buds and shoots as well as those promoting callus proliferation. Complete plant regeneration was obtained only by first culturing the leaf explants in a medium with NAA and BA to induce formation of buds, and subsequently transferring them to a medium without growth regulators to achieve the further development of shoots.
Simulations of a Graphene Nanoflake as a Nanovector To Improve ZnPc Phototherapy Toxicity: From Vacuum to Cell Membrane
2017
International audience; We propose a new approach to improving photodynamic therapy (PDT) by transporting zinc phthalocyanine (ZnPc) in biological systems via a graphene nanoflake, to increase its targeting. Indeed, by means of time-dependent density functional theory simulations, we show that the ZnPc molecule in interaction with a graphene nanoflake preserves its optical properties not only in a vacuum but also in water. Moreover, molecular dynamic simulations demonstrate that the graphene nanoflake/ZnPc association, as a carrier, permits one to stabilize the ZnPc/graphene nanoflake system on the cellular membrane, which was not possible when using ZnPc alone. We finally conclude that the…
Analysis of Drosophila salivary gland, epidermis and CNS development suggests an additional function of brinker in anterior-posterior cell fate speci…
2000
Salivary glands are simple structured organs which can serve as a model system in the study of organogenesis. Following a large EMS mutagenesis we have identified a number of genes required for normal salivary gland development. Mutations in the locus small salivary glands-1 (ssg-1) lead to a drastic reduction in the size of the salivary glands. The gene ssg-1 was cloned and subsequent sequence and genetic analysis showed identity to the recently published gene brinker. The salivary gland placode in brinker mutants appears reduced along both the anterior-posterior and dorso-ventral axis. Analysis of the brinker cuticle phenotype revealed a similar loss of anterior-posterior as well as later…
The catalytic performance of mesoporous cerium oxides prepared through a nanocasting route for the total oxidation of naphthalene
2010
Cerium oxides have been prepared by nanocasting of a mesoporous siliceous KIT-6. Through this synthesis method a partially ordered mesoporous structure, as demonstrated by several characterization techniques (N2 adsorption, XRD and HRTEM) has been obtained. Accordingly, very high surface areas have been achieved (up to 163 m2/g), despite using high calcination temperatures (550 °C). We have demonstrated that the aging temperature of the siliceous template is of outstanding importance, as this parameter is directly responsible for both the pore size and the surface area of the catalysts. In addition, whilst a low preparation temperature (40 °C) makes the further removal of the silica templat…
Sequestration of organomettalic compounds by synthetic and naturally occuring polycarboxylate ligands. Binding of monomethylmercury(II) by polyacryli…
2007
The sequestering capacity of synthetic and naturally occurring polycarboxylate ligands towards mono- methylmercury(II) was evaluated by stability quantitative data on the interaction of CH3Hgþ with different molecular weight synthetic polyacrylates (2 and 20 kDa average M.wt) and alginate (70– 100 kDa) extracted from brown algae Macrocystis pyrifera. The influence of ionic medium was evaluated by measurements on the CH3Hgþ-polyacrylate systems in NaNO3 medium at different ionic strengths (0.10, 0.25, 0.50 and 0.75mol Lÿ1), and a Debye–Hu¨ ckel type equation was used for the dependence of complex formation constants on ionic strength. Measurements on the CH3Hgþ - alginate system were carried…
A Rational Design for Imidazolate-Bridged Linear Trinuclear Compounds from Mononuclear Copper(II) Complexes with 2-[((Imidazol-2-ylmethylidene)amino)…
2001
Two mononuclear copper(II) complexes with the unsymmetrical tridentate ligand 2-[((imidazol-2-ylmethylidene)amino)ethyl]pyridine (HL), [Cu(HL)(H2O)](ClO4)2.2H2O (1) and [Cu(HL)Cl2] (2), have been prepared and characterized. The X-ray analysis of 2 revealed that the copper(II) ion assumes a pentacoordinated square pyramidal geometry with an N3Cl2 donor set. When 1 and 2 are treated with an equimolecular amount of potassium hydroxide, the deprotonation of the imidazole moiety promotes a self-assembled process, by coordination of the imidazolate nitrogen atom to a Cu(II) center of an adjacent unit, leading to the polynuclear complexes [[Cu(L)(H2O)](ClO4)]n (3) and [[Cu(L)Cl].2H2O]n (4). Variab…