ABSTRACT
The performance of mechanochemically synthesized supported bimetallic AgAu nanoalloy catalysts was evaluated in the oxidative cleavage of methyl oleate, a commonly available unsaturated bio-derived raw material. An extensive screening of supports (SiO2 , C, ZrO2 , Al2 O3 ), metallic ratios (Ag : Au), reaction times, temperatures, and use of solvents was carried out. The performance was optimized towards productivity and selectivity for the primary cleavage products (aldehydes and oxoesters). The optimal conditions were achieved in the absence of solvent, using Ag8 Au92 /SiO2 as catalyst, at 80 °C, reaction time of 1â h, substrate to catalyst=555 and 10â bar of molecular oxygen. A strong support effect was observed: the selectivity to aldehydes was best with silica as support, and to esters was best using zirconia. This shows not only that mechanochemical preparation of bimetallic catalysts is a powerful tool to generate useful catalyst compositions, but also that a safe, green, solventless synthesis of bio-derived products can be achieved by aerobic oxidative cleavage.
ABSTRACT
Herein, we report a class of molecular spherical nucleic acid (SNA) nanostructures. These nano-sized single molecules are synthesized from T8 polyoctahedral silsesquioxane and buckminsterfullerene C60 scaffolds, modified with 8 and 12 pendant DNA strands, respectively. These conjugates have different DNA surface densities and thus exhibit different levels of nuclease resistance, cellular uptake, and gene regulation capabilities; the properties displayed by the C60 SNA conjugate are closer to those of conventional and prototypical gold nanoparticle SNAs. Importantly, the C60 SNA can serve as a single entity (no transfection agent required) antisense agent to efficiently regulate gene expression. The realization of molecularly pure forms of SNAs will open the door for studying the interactions of such structures with ligands and living cells with a much greater degree of control than the conventional polydisperse forms of SNAs.
Subject(s)
Models, Molecular , Nucleic Acid Conformation , Poly T/chemistryABSTRACT
In this report, the highly efficient Rose Bengal-catalysed C(sp2)-H selenylation of indoles, imidazoles and arenes was achieved using a half molar equiv. of diorganoyl diselenides. This metal-free, photo-induced protocol resulted in selenylated products in good to excellent yields. The reaction features are high yields, an atom-economic, gram-scalable and metal-free approach, and applicability to different biologically relevant (hetero)arenes.
ABSTRACT
Unsupported bimetallic Co/Pt nanoparticles (NPs) of 4.4 ± 1.9 nm can be easily obtained by a simple reaction of [bis(cylopentadienyl)cobalt(ii)] and [tris(dibenzylideneacetone) bisplatinum(0)] complexes in 1-n-butyl-3-methylimidazolium hexafluorophosphate IL at 150 °C under hydrogen (10 bar) for 24 h. These bimetallic NPs display core-shell like structures in which mainly Pt composes the external shell and its concentration decreases in the inner-shells (CoPt3@Pt-like structure). XPS and EXAFS analyses show the restructuration of the metal composition at the NP surface when they are subjected to hydrogen and posterior H2S sulfidation, thus inducing the migration of Co atoms to the external shells of the bimetallic NPs. Furthermore, the isolated bimetallic NPs are active catalysts for the Fischer-Tropsch synthesis, with selectivity for naphtha products.
ABSTRACT
A new class of potential pharmacological thiophenes and furans compounds has been prepared. The obtained thiophenes and furans derivatives were screened for anti-inflammatory, antinociceptive and antioxidant activity in rats. In vitro hepatic ALA-D activity was also evaluated. Thiophene 2 exhibited higher anti-inflammatory effect than thiophenes 1 and 3. However, compound 1 demonstrated lower IC(50) for lipid peroxidation than 2 and 3 in liver and brain. Furan compounds 4-6 presented similar anti-inflammatory activity. The acetylenic furans 4 and 5 inhibited scarcely lipid peroxidation at low concentration as 10 µM. Conversely, furan compound 6 was the most effective against lipid peroxidation in liver. Furans 4 and 5 inhibited lipid peroxidation, in brain, only in high concentrations. In contrast, furan 6 protected (90%) against lipid peroxidation at 10 µM. Thiophene 1 was devoid of anti-inflammatory activity but was efficient in reducing acetic acid-induced constriction. Conversely, it analogue furan 4 presented anti-inflammatory and antinociceptive activity. Thiophene and furan inhibited hepatic ALA-D only at high concentrations. All compounds displayed antioxidant activity however the anti-inflammatory activity is not related to antioxidant potential.
