Innenrücktitelbild: Manganese‐Catalyzed Direct Nucleophilic C(sp2)?H Addition to Aldehydes and Nitriles (Angew. Chem. 46/2015)

Herein, a manganese‐catalyzed nucleophilic addition of inert C(sp²) H bonds to aldehydes and nitriles is disclosed by virtue of a dual activation strategy. The reactions feature mild reaction conditions, excellent regio‐ and stereoselectivity, and a wide substrate scope, which includes both aromatic and olefinic C H bonds, as well as a large variety of aldehydes and nitriles. Moreover, mechanistic studies shed light on possible catalytic cycles.     

Surfactant-Free and Controlled Synthesis of Hexagonal CeVO4 Nanoplates: Photocatalytic Activity and Superhydrophobic Property

Nanomaterials with both superhydrophobic surface properties as well as photocatalytic activities could have important industrial applications. Herein, we synthesized CeVO₄ nanocrystals with hexagonal nanoplate structures from the reaction of decavanadate (K₆V₁₀O₂₈⋅9 H₂O) and CeCl₃⋅H₂O precursors via a hydrothermal method. This synthetic route has four advantages: 1) the reaction condition is relatively mild, 2) it doesn′t need surfactants or templates, 3) it requires no expensive equipment, and 4) products are of higher purity. During synthesis, solution pH, and reaction temperature were found to play important roles in determining the growth process and final morphologies of the CeVO₄ products. These products were characterized spectrophotometrically and via scanning and transmission electron microscopy. Furthermore, the wettability of the as-synthesized film CeVO₄ nanoplates was studied by measuring water contact angle (CA). The largest CA measured was at 169.5 ° for a glass substrate treated with 0.06 g mL⁻¹ CeVO₄ followed by 2 % 1 H, 1 H, 2 H, 2 H-perfluorodecyltriethoxysilane. Finally, the CeVO₄ nanoplates exhibited excellent photocatalytic activity in degradation of rhodamine B (RhB) under UV irradiation and was stable even after repeated cycles of use.     

Charged AdS black holes with finite electrodynamics in 4D Einstein-Gauss-Bonnet gravity

Using a modified expression for the electric potential in the context of T-duality [Gaete and Nicolini, Phys. Lett. B, 2022], we obtained an exact charged solution within the 4D Einstein-Gauss-Bonnet (4D EGB) theory of gravity in the presence of a cosmological constant. We show that the solution also exists in the regularized 4D EGB theory. Moreover, we point out a correspondence between the black hole solution in the 4D EGB theory and the solution in the non-relativistic Horava–Lifshitz theory. The black hole solution is regular and free from singularity. As a special case, we derive a class of well known solutions in the literature.     

Simple and Fast Picomolar Detection of Ochratoxin A Using a Reusable Label Free Aptasensor Built with a Layer‐by‐layer Procedure

A label free impedimetric aptasensor for simple, fast and reusable picomolar detections of Ochratoxin A (OTA) in grape juices was designed. Two main factors were observed to affect the accurate detections of the toxin: i‐lateral interactions between self‐assembled aptamers ii‐ adsorption of large molecules present in complex matrixes like grape juices. Lateral interactions between aptamers were minimized by constructing the aptasensor in a Layer‐by‐Layer procedure. The interferences associated to the unspecific and irreversible adsorption of large molecules present in grape juice, were reduced by submitting samples to ultrafiltration prior to analysis. With this protocol, a 0.12 pM limit of detection and 0.24 pM limit of quantification in spiked grape juices were achieved after only 5–7 mins of interaction with the samples. The presented aptasensor can be recovered after a simple immersion in hot water (90 °C) for ten minutes.     

Calix[4]arene-based crab-like molecular sensors for highly selective detection of mercury and copper ions

In this work, two novel chemosensors based on calix[4]arene bearing (thio)barbituric acid groups (BC1 and BC2) were synthesised, and their structures were characterised by HRMS, NMR and FTIR. Furthermore, their binding properties towards various biologically relevant metal ions were studied by fluorescence titrations, ¹H NMR spectroscopies and Job’s plot evaluations. The chemosensor BC1 displayed excellent binding affinity and selectivity towards Cu²⁺, which was characterised using fluorescence spectroscopy. On the other hand, BC2 exhibited a very remarkable fluorescence enhancement as well as visible colour change from pale green to sunset yellow, in presence of Hg²⁺ ions. Finally, Job’s plot method revealed 1:1 binding stoichiometry for both BC1:Cu²⁺ complex and BC2:Hg²⁺ complex.