Conformational Analysis of the Anti‐obesity Drug Lorcaserin in Water: How To Take Advantage of Long‐Range Residual Dipolar Couplings

The conformational state of 8‐chloro‐1‐methyl‐2,3,4,5‐tetrahydro‐1H‐3‐benzazepine hydrochloride (lorcaserin) in water has been determined on the basis of one‐bond and long‐range C? H residual dipolar coupling (RDC) data along with DFT computations and ³J_HH coupling‐constant analysis. According to this analysis, lorcaserin exists as a conformational equilibrium of two crown‐chair forms, of which the preferred conformation has the methyl group in an equatorial orientation.     

Enzyme‐Responsive Silica Mesoporous Supports Capped with Azopyridinium Salts for Controlled Delivery Applications

The preparation of a new capped silica mesoporous material, Rh‐Azo‐S , for on‐command delivery applications in the presence of target enzymes is described. The material consists of nanometric mesoporous MCM‐41‐like supports loaded with Rhodamine B and capped with an azopyridine derivative. The material was designed to show “zero delivery” and to display a cargo release in the presence of reductases and esterases, which are usually present in the colon, mainly due to intestinal microflora. The opening and cargo release of Rh‐Azo‐S in vitro studies were assessed and seen to occur in the presence of these enzymes, whereas no delivery was noted in the presence of pepsine. Moreover, Rh‐Azo‐S nanoparticles were used to study controlled Rhodamine B dye delivery in intracellular media. HeLa cells were employed for testing the “non”‐toxicity of nanoparticles. Moreover, delivery of the dye in these cells, through internalization and enzyme‐mediated gate opening, was confirmed by confocal microscopy. Furthermore, the nanoparticles capped with the Azo group and loaded with a cytotoxic camptothecin ( CPT ) were also prepared (solid CPT‐Azo‐S ) and used as delivery nanodevices in HeLa cells. When this solid was employed, the cell viability decreased significantly due to internalization of the nanoparticles and delivery of the cytotoxic agent.     

Cu2O/CuO Electrocatalyst for Electrochemical Reduction of Carbon Dioxide to Methanol

Herein, we report the controlled and direct fabrication of Cu₂O/CuO thin film on the conductive nickel foam using electrodeposition route for the electrochemical reduction of carbon dioxide (CO₂) to methanol. The electrocatalytic reduction was performed in CO₂ saturated aqueous solution consisting of KHCO₃, pyridine and HCl at room temperature. CO₂ reduction was carried out at a constant potential of −1.3 V for 120 min to study the electrochemical performance of the prepared electrocatalysts. Cu₂O/CuO shows better electrocatalytic activity with highest current density of 46 mA/cm². The prepared catalyst can be an efficient and selective electrode for the production of methanol.     

Inter-network magnetic interactions in GdMexMn1−xO3 perovskites (Me=transition metal)

The gadolinium-based manganite GdMnO₃ of perovskite structure has been partially substituted at the manganese site by transition metal elements Me like Cu, Ni and Co, leading to a general formula GdMe_xMn_1−xO₃, in which different magnetic entities (e.g., Gd³⁺, Cu²⁺, Ni²⁺, Co²⁺, Co³⁺, Mn³⁺, Mn⁴⁺) can coexist, depending on charge equilibrium conditions. For divalent cations such as Cu²⁺ and Ni²⁺, the solid solution extends from x  (Me)=0–0.5, with O-type orthorhombic symmetry (a<c/√2<b)$\left(a<c/\surd 2<b\right)$. When the substituting element is cobalt, the solid solution extends over the whole range [0?x  ?1], changing from O′-type symmetry (c/√2<a<b)$\left(c/\surd 2<a<b\right)$ to O-type for x>0.5. In this latter case, the synthesis is performed under oxygen flow, which allows the cobalt ion to take a 3+ oxidation state.     

Polyesters by a Radical Pathway: Rationalization of the Cyclic Ketene Acetal Efficiency

Radical ring-opening polymerization (rROP) of cyclic ketene acetals (CKAs) combines the advantages of both ring-opening polymerization and radical polymerization thereby allowing the robust production of polyesters coupled with the mild polymerization conditions of a radical process. rROP was recently rejuvenated by the possibility to copolymerize CKAs with classic vinyl monomers leading to the insertion of cleavable functionality into a vinyl-based copolymer backbone and thus imparting (bio)degradability. Such materials are suitable for a large scope of applications, particularly within the biomedical field. The competition between the ring-opening and ring-retaining propagation routes is a major complication in the development of efficient CKA monomers, ultimately leading to the use of only four monomers that are known to completely ring-open under all experimental conditions. In this article we investigate the radical ring-opening polymerization of model CKA monomers and demonstrate by the combination of DFT calculations and kinetic modeling using PREDICI software that we are now able to predict in silico the ring-opening ability of CKA monomers.     

Determination of personal care products in water using UHPLC–MS after solid phase extraction with mesoporous silica‐based MCM‐41 functionalized with cyanopropyl groups

A silica‐based MCM‐41 mesoporous material functionalized with cyanopropyl groups has been synthesized by cocondensation, characterized and applied to preconcentrate six parabens and three UV filters in river and swimming‐pool waters. The analytes were quantified by ultra‐high performance liquid chromatography‐tandem mass spectrometry, according to the Directive 96/23/EC. Even though matrix effect was negligible, quantification in river water samples with the standard addition approach improved the recoveries obtained using solvent‐based and even with matrix‐matched calibration. The method quantification limits in river water samples were 0.05 ng/mL for 2,4‐dihydroxybenzophenone and 0.01 ng/mL for the rest. Recoveries, evaluated for a concentration level of 0.5 ng/L, were in the range 93.5‐107.6% for parabens and in the range 64.2‐85.8% for UV filters, with relative standard deviations intraday ≤10.2 and 10.8%, respectively. This parameter, evaluated for a concentration level of 0.1 ng/L, ranged between 98.3 and 110.4% for parabens and between 61.9 and 89.9% for UV filters, with relative standard deviation intraday ≤15.3 and 15.5%, respectively. The two UV filters with lower recoveries were the most affected by the addition of sodium chloride. River and swimming pool waters were analyzed and all the personal care products were found in the swimming pool water, whereas only methylparaben was detected in the river water.     

Effect of the catalyst structure on the catalytic activity in dehydrogenation of 2-methyl butane

Calorimetry, thermogravimetry, X-ray diffraction analysis, and low-temperature adsorption of nitrogen were used to study the structure of bimetallic Pt—Sn catalysts on zinc–alumina spinel supports. The effect of the porous structure of the catalyst samples synthesized on their catalytic activity in dehydrogenation of 2–methyl butane was analyzed.     

Mechanical Behavior of Polymer Gels for RDCs and RCSAs Collection: NMR Imaging Study of Buckling Phenomena

Anisotropic NMR parameters, such as residual dipolar couplings (RDCs), residual chemical shift anisotropies (RCSAs) and residual quadrupolar couplings (RQCs or Δν_Q), appear in solution‐state NMR when the molecules under study are subjected to a degree of order. The tunable alignment by reversible compression/relaxation of gels (PMMA and p‐HEMA) is an easy, user‐friendly, and very affordable method to measure them. When using this method, a fraction of isotropic NMR signals is observed in the NMR spectra, even at a maximum degree of compression. To explain the origin of these isotropic signals we decided to investigate their physical location inside the NMR tube using deuterium 1D imaging and MRI micro‐imaging experiments. It was observed that after a certain degree of compression the gels start to buckle and they generate pockets of isotropic solvent, which are never eliminated. The amount of buckling depends on the amount of cross‐linker and the length of the gel.     

Self‐Assembly of Uranyl–Peroxide Nanocapsules in Basic Peroxidic Environments

A wide range of uranyl–peroxide nanocapsules have been synthesized using very simple reactants in basic media; however, little is known about the process to form these species. We have performed a density functional theory study of the speciation of the uranyl ions under different experimental conditions and explored the formation of dimeric species via a ligand exchange mechanism. We shed some light onto the importance of the excess of peroxide and alkali counterions as a thermodynamic driving force towards the formation of larger uranyl–peroxide species.     

ZnO–SnO2 branch–stem nanowires based on a two-step process: Synthesis and sensing capability

ZnO–SnO₂ branch–stem nanostructures were realized on a basis of a two-step process. In step 1, SnO₂-stem nanowires were synthesized. In step 2, ZnO-branch nanowires were successfully grown on the SnO₂-stem nanowires through a simple evaporation technique. We have pre-deposited thin Au layers on the surface of SnO₂ nanowire stems and subsequently evaporated Zn powders on the nanowires. The ZnO branches, which sprouted from the SnO₂ stems, had diameters in a range of 30–35 nm. As-synthesized branches were of single crystalline hexagonal ZnO structures. Since the branch tips were comprised of Au-containing nanoparticles, the Au-catalyzed vapor–liquid–solid growth mechanism was more likely to control the growth process of the ZnO branches. To test a potential use of ZnO–SnO₂ branch–stem nanostructures in chemical gas sensors, their sensing performances with respect to NO₂ gas were investigated, showing the promising potential in chemical gas sensors.