NMR Signatures of the Active Sites in Sn‐β Zeolite

Dynamic nuclear polarization surface enhanced NMR (DNP‐SENS), Mössbauer spectroscopy, and computational chemistry were combined to obtain structural information on the active‐site speciation in Sn‐β zeolite. This approach unambiguously shows the presence of framework Sn^IV‐active sites in an octahedral environment, which probably correspond to so‐called open and closed sites, respectively (namely, tin bound to three or four siloxy groups of the zeolite framework).     

Lab‐on‐a‐Chip Reactor Imaging with Unprecedented Chemical Resolution by Hadamard‐Encoded Remote Detection NMR

The development of microfluidic processes requires information‐rich detection methods. Here we introduce the concept of remote detection exchange NMR spectroscopy (RD‐EXSY), and show that, along with indirect spatial information extracted from time‐of‐flight data, it provides unique information about the active regions, reaction pathways, and intermediate products in a lab‐on‐a‐chip reactor. Furthermore, we demonstrate that direct spatial resolution can be added to RD‐EXSY efficiently by applying the principles of Hadamard spectroscopy.     

A Membraneless Glucose/O2 Biofuel Cell Based on Pd Aerogels

In this study, we introduce the first membraneless glucose/O₂ biofuel cell using Pd‐based aerogels as electrode materials. The bioanode was fabricated with a coimmobilized mediator and glucose oxidase for the oxidation of glucose, in which ferrocenecarboxylic acid was integrated into a three‐dimensional porous beta‐cyclodextrin‐modified Pd aerogel to mediate the bioelectrocatalytic reaction. Bilirubin oxidase and Pd–Pt alloy aerogel were confined to an electrode surface, which realized the direct bioelectrocatalytic function for the reduction of O₂ to H₂O with a synergetic effect at the biocathode. By employing these two bioelectrodes, the assembled glucose/O₂ biofuel cell showed a maximum power output of 20 μW cm^?2 at 0.25 V.     

Methods to ease the release of thin polydimethylsiloxane films from difficult substrates

Silicone elastomers are used as dielectric electroactive polymers for making actuators, generators, sensors, and as artificial muscles in medical applications. Current requirements in the actuator manufacturing put a strict limitation on the thickness of the elastomers, such that a maximum permissible thickness is around 25–50 µm. The relatively small Young's modulus for these elastomers is a requirement for actuation capabilities. However, peeling and release of such films during manufacture processes are very difficult. To ease the release of the films, techniques such as the use of release agents like surfactants and detergents, incorporating resins in the silicone matrix and grafting/adding low surface energy functionalities to the silicone elastomer have been tested. The methods used are required not to interfere with the Young's modulus and the dielectric permittivity in a negative way. Polysorbate‐20, a non‐ionic surfactant, fulfills all requirements and gives the lowest peel forces for the films. Copyright © 2013 John Wiley & Sons, Ltd.     

Characterization of New Specific Copper Chelators as Potential Drugs for the Treatment of Alzheimer’s Disease

The non‐controlled redox‐active metal ions, especially copper, in the brain of patients with Alzheimer disease (AD) should be considered at the origin of the intense oxidative damage in the AD brain. Several bis(8‐aminoquinoline) ligands, such as 1 and PA1637, are able to chelate Cu²⁺ with high affinity, and are specific chelators of copper with respect to iron and zinc. They are able to efficiently extract Cu²⁺ from a metal‐loaded amyloid. In addition, these tetradentate ligands are specific for the chelation of Cu²⁺ compared with Cu⁺. Consequently, the copper ion is easily released from the bis(8‐aminoquinoline) ligand under reductive conditions, and can be trapped again by a protein having some affinity for copper such as human serum albumin (HSA) proteins. In addition, the copper is not efficiently released from [Cu(CQ)₂] in reductive conditions. The catalytic production of H₂O₂ by [Cu²⁺‐Aβ_1?28]/ascorbate is inhibited in vitro by the bis(8‐aminoquinoline) 1 , suggesting that 1 should be able to play a protective role against oxidative damages induced by copper‐loaded amyloids.     

Unusual behaviour of pyridinylboronic acids in the Petasis boronic Mannich reaction

The implementation of the Petasis boronic Mannich reaction in pyridine series allowed us to obtain original compounds whose structure was investigated and determined a stable complex (1:1) of dioxaborolanone and amine.     

Stereocontrolled synthesis and cycloaddition of 1,2,4-trioxygenated 1,3-dienes

A new stereocontrolled synthetic pathway to 1,2,4-trioxygenated 1,3-dienes from pyruvic aldehyde dimethyl acetal (14a) is described. Reacting the cyclohexylamine-derived imine of this starting material with chloroalkyl ethers under basic conditions affords ketoacetals 18-20, which were then transformed into eight different enoxysilanes 12. A delta-elimination triggered by tert-butyllithium yields 1,2,4-trioxygenated dienes 13. Increasing the bulkiness of the silyloxy group or that of the acetal moiety leads stereoselectively to the (1E,3E) or (1Z,3E) isomers of 13, respectively. Hyperbaric [4 + 2] cycloadditions between 13 (13c, 13d, 13g) and N-methylmaleimide or methyl- and phenylacrylates give access to the expected cycloadducts with fine stereo- and regiocontrol.     

Synthesis of original thiazoloindolo[3,2-c]quinoline and novel 8-N-substituted-11H-indolo[3,2-c]quinoline derivatives from benzotriazoles. Part I

Synthesis of novel thiazoloindolo[3,2-c]quinoline and 8-substituted-11H-indolo[3,2-c]quinolines was performed via Graebe-Ullmann thermal cyclization from appropriated N-arylated benzotriazoles. 7H-4,7-Diaza-benzo[de]anthracene, a by-product reaction structurally closed to pyridoacridine skeleton was also identified.     

Formation of Aromatic and Other Unsaturated End Groups in Carboxymethyl Cellulose During Hot Alkaline Treatment

Carboxymethyl cellulose (CMC, DS 0.58) was treated in solutions of sodium hydroxide (0.001–1 M) at 95 °C. The treated (1–12 h) CMC samples were purified by dialysis and analyzed by UV spectroscopy and by UV resonance Raman spectroscopy (UVRRS) with excitation at 244 nm. A UV absorption maximum at 265 nm and a UVRR signal at 1650 cm⁻¹ were indicative of formation of -conjugated aldehyde end groups in CMC through -elimination. Another strong UVRR band at 1610 cm⁻¹ gave evidence on conversion of some of the -conjugated aldehyde end groups to alkali stable aromatic structures.     

Screening analyses of pinosylvin stilbenes, resin acids and lignans in Norwegian conifers

The content and distribution of stilbenes and resin acids in Scots pine (Pinus sylvestris) and spruce (Picea abies), sampled in central Norway, have been examined.The contents of pinosylvin stilbenes in pine heartwood/living knots were 0.2-2/2-8 %(w/w). No stilbenes could be detected in spruce (Picea abies). The resin acid contents of pine sapwood/heartwood and knots were 1-4 and 5-10 % (w/w), respectively. Minor amounts of resin acids (<0.2/<0.04 %w/w) were identified in spruce wood/knots. The lignan content in knots of Norwegian spruce was 6.5 % (w/w). Diastereomerically pure hydroxymatairesinol (HMR, 84 % of total lignans) was readily isolated from this source since only minor quantities (2.6 % of total lignans) of the allo-HMR diastereomer was detected. Insignificant amounts of lignans were present in the sapwood. Lignans could not be detected in the sapwood or knots of Norwegian sallow (Salix caprea), birch(Betula pendula) or juniper (Juniperus communis).