Characterization of gluten-free bread crumb baked at atmospheric and reduced pressures using TD-NMR

This research aimed to study the effects of using a partial vacuum for bread baking on macromolecules and water distribution in gluten-free bread. Bread baking under partial vacuum results in greater oven rise and a larger gas fraction in the crumb. Because water's boiling point decreases under reduced pressure, it was expected that its distribution within the dough and its interactions with the others dough's constituents (mainly starch) would differ from those in bread baked under atmospheric pressure. Time-domain nuclear magnetic resonance was used, as it has the rare capacity to quantify both gelatinization and retrogradation of starch. Complementary rheological measurements made it possible to show that crumb Young's modulus was mostly influenced by the gas fraction whereas there was little change in starch gelatinization and retrogradation when dough was baked under partial vacuum. When insufficiently hydrated (48%), the volume of breads was practically the same whatever the baking process. Meanwhile, the nuclear magnetic resonance results suggested that amylose short-term crystallization (on cooling) is dependent on water content. In addition, crumb Young's modulus during storage at room temperature correlated with an increase in free induction decay signal intensity.     

Cyclic(Alkyl)(Amino)Carbene (CAAC)-Supported Zn Alkyls: Synthesis,Structure and Reactivity in Hydrosilylation Catalysis

The reactivity of Zn^II dialkyl species ZnMe₂ with a cyclic(alkyl)(amino)carbene, 1-[2,6-bis(1-methylethyl)phenyl]-3,3,5,5-tetramethyl-2-pyrrolidinylidene (CAAC, 1 ), was studied and extended to the preparation of robust CAAC-supported Zn^II Lewis acidic organocations. CAAC adduct of ZnMe₂ ( 2 ), formed from a 1:1 mixture of 1 and ZnMe₂, is unstable at room temperature and readily undergoes a CAAC carbene insertion into the Zn−Me bond to produce the ZnX₂-type species (CAAC-Me)ZnMe ( 3 ), a reactivity further supported by DFT calculations. Despite its limited stability, adduct 2 was cleanly ionized to robust two-coordinate (CAAC)ZnMe⁺ cation ( 5⁺ ) and derived into (CAAC)ZnC₆F₅⁺ ( 7⁺ ), both isolated as B(C₆F₅)₄⁻ salts, showing the ability of CAAC for the stabilization of reactive [ZnMe]⁺ and [ZnC₆F₅]⁺ moieties. Due to the lability of the CAAC−ZnMe₂ bond, the formation of bis(CAAC) adduct (CAAC)₂ZnMe⁺ cation ( 6⁺ ) was also observed and the corresponding salt [ 6 ][B(C₆F₅)₄] was structurally characterized. As estimated from experimental and calculations data, cations 5⁺ and 7⁺ are highly Lewis acidic species and the stronger Lewis acid 7⁺ effectively mediates alkene, alkyne and CO₂ hydrosilylation catalysis. All supporting data hints at Lewis acid type activation–functionalization processes. Despite a lower energy LUMO in 5⁺ and 7⁺ , their observed reactivity is comparable to those of N-heterocyclic carbene (NHC) analogues, in line with charge-controlled reactions for carbene-stabilized Zn^II organocations.     

Multicomponent Aromatic and Benzylic Mannich Reactions through C−H Bond Activation

Multicomponent Mannich reactions through C−H bond activation are described. These transformations allowed for the straightforward generation of densely substituted benzylic and homo-benzylic amines in good yields. The reaction involves a reaction between two transient species: an organometallic species, generated by transition-metal-catalyzed sp² or sp³ C−H bond activation and an in situ generated imine. The use of an acetal as an aldehyde surrogate was found essential for the reaction to proceed. The process could be successfully applied to Rh^III-catalyzed sp² C−H bond functionalization and extended to Cu^II-catalyzed sp³ C−H bond functionalization.     

Chemo-Enzymatic Synthesis of S. mansoni O-Glycans and Their Evaluation as Ligands for C-Type Lectin Receptors MGL,DC-SIGN,and DC-SIGNR

Due to their interactions with C-type lectin receptors (CLRs), glycans from the helminth Schistosoma mansoni represent promising leads for treatment of autoimmune diseases, allergies or cancer. We chemo-enzymatically synthesized nine O-glycans based on the two predominant O-glycan cores observed in the infectious stages of schistosomiasis, the mucin core 2 and the S. mansoni core. The O-glycans were fucosylated next to a selection of N-glycans directly on a microarray slide using a recombinant fucosyltransferase and GDP-fucose or GDP-6-azidofucose as donor. Binding assays with fluorescently labelled human CLRs DC-SIGN, DC-SIGNR and MGL revealed the novel O-glycan O8 as the best ligand for MGL from our panel. Significant binding to DC-SIGN was also found for azido-fucosylated glycans. Contrasting binding specificities were observed between the monovalent carbohydrate recognition domain (CRD) and the tetravalent extracellular domain (ECD) of DC-SIGNR.     

Ambipolar Discotic Liquid Crystals Built Around Platinum Diimine-Dithiolene Cores

Platinum diimine dithiolene complexes bearing mesogenic groups on one or both ligands have been prepared through an original ligand metathesis reaction to introduce the dithiolene ligand. The neutral diimine ligands, the intermediate platinum dichloride diimine complexes, and the target compounds were characterized by a combination of electronic (electrochemistry, absorption and emission spectroscopy, DFT calculations) and structural (SAXS, DSC) tools. Several novel liquid crystalline platinum diimine-dithiolene were identified over a large temperature range, and the systems were endowed with ambipolar properties, associated with the high reversibility of both oxidation and reduction processes.     

The remediation of wastewater containing 4-chlorophenol using integrated photocatalytic and biological treatment

In this work, the performance of integrated photocatalytic and biological treatment was studied for the degradation of 4-chlorophenol (MCP) present in wastewaters. Photocatalysis was used as a pre-treatment to biological degradation. Pollutant removal efficiency was quantified using MCP removal and total organic carbon (TOC) removal. Both photocatalytic as well as biological treatments were carried out in batch reactors, using TiO₂ as the photocatalyst. The inoculum for biological experiments was obtained from paper mill effluent treatment plant and was developed through a process of selection and acclimatization. Effect of TiO₂ concentration on the photocatalytic degradation of MCP was studied along with the effect of the duration of photochemical oxidation and glucose concentrations (0 g/L, 1 g/L and 2 g/L) on the biodegradation of MCP. Integrated biological and photochemical degradation was found to be more effective in treating MCP, especially at higher concentrations (400 mg/L). An initial MCP concentration of 400 mg/L required 96 h for complete mineralization when treated with the process combination, whereas the treatment went on up to 264 h when biodegradation alone was employed.     

Synthesis of functionalized 2-arylpyridines from 2-halopyridines and various aryl halides via a nickel catalysis

An efficient nickel-catalyzed method devoted to the direct formation of functionalized 2-arylpyridines is described avoiding the prior preparation of organometallic species. Various functionalized 2-arylpyridines are obtained in moderate to excellent yields by a one-step chemical procedure from corresponding halides. The NiBr₂(2,2′-bipyridine) complex appears to be an extremely suitable catalyst for the activation in the presence of manganese dust of aromatic halides and pyridyl halides functionalized by reactive groups. The versatility of this original process represents a simple alternative to most known methods using organometallic reagents.     

Guests of differing polarities provide insight into structural requirements for templates of water-soluble nano-capsules

Guests covering a range of polarities were examined for their ability to bind to a water-soluble cavitand and trigger its assembly into a supramolecular capsule. Specifically the guests examined were: tridecane 2, 1-dodecanol 3, 2-nonyloxy ethanol (ethylene glycol monononyl ether) 4, 2-(2-hexyloxyethoxy) ethanol (di(ethylene glycol) hexyl ether) 5, 2-[2-(2 propoxyethoxy)ethoxy] ethanol (tri(ethylene glycol) propyl ether) 6, and bis [2-(2-hydroxyethoxy)ethyl] ether (tetra(ethylene glycol)) 7. In this series, guest 6 proved to signify the boundary between assembly and the formation of 2:1 complexes, and simple 1:1 complexation. Thus, guests 2-5 formed relatively kinetically stable capsules, guest 6 formed a capsule that was unstable relative to the NMR timescale, and guest 7 formed a simple 1:1 complex.     

Cobalt‐Catalyzed Formation of Symmetrical Biaryls and Its Mechanism

Effective devotion : An efficient cobalt‐catalyzed method devoted to the formation of symmetrical biaryls is described avoiding the preparation of organometallic reagents. Various aromatic halides functionalized by a variety of reactive group reagents are employed. Preliminary DFT calculations have shown that the involvement of a Co^I/Co^III couple is realistic at least in the case of 1,3‐diazadienes as ligands (FG=functional group).

     

The 6,6‐Dicyanopentafulvene Core: A Template for the Design of Electron‐Acceptor Compounds

The electron‐accepting ability of 6,6‐dicyanopentafulvenes (DCFs) can be varied extensively through substitution on the five‐membered ring. The reduction potentials for a set of 2,3,4,5‐tetraphenyl‐substituted DCFs, with varying substituents at the para‐position of the phenyl rings, strongly correlate with their Hammett σ_p‐parameters. By combining cyclic voltammetry with DFT calculations ((U)B3LYP/6‐311+G(d)), using the conductor‐like polarizable continuum model (CPCM) for implicit solvation, the absolute reduction potentials of a set of twenty DCFs were reproduced with a mean absolute deviation of 0.10 eV and a maximum deviation of 0.19 eV. Our experimentally investigated DCFs have reduction potentials within 3.67–4.41 eV, however, the computations reveal that DCFs with experimental reduction potentials as high as 5.3 eV could be achieved, higher than that of F₄‐TCNQ (5.02 eV). Thus, the DCF core is a template that allows variation in the reduction potentials by about 1.6 eV.