Showing papers in "ChemistryOpen in 2018"
TL;DR: The multidisciplinary aspects of research on artificial molecular machines are discussed, with the help of a few examples, to highlight its translational character.
Abstract: Movement is one of the central attributes of life, and a key feature in many technological processes. While artificial motion is typically provided by macroscopic engines powered by internal combustion or electrical energy, movement in living organisms is produced by machines and motors of molecular size that typically exploit the energy of chemical fuels at ambient temperature to generate forces and ultimately execute functions. The progress in several areas of chemistry, together with an improved understanding of biomolecular machines, has led to the development of a large variety of wholly synthetic molecular machines. These systems have the potential to bring about radical innovations in several areas of technology and medicine. In this Minireview, we discuss, with the help of a few examples, the multidisciplinary aspects of research on artificial molecular machines and highlight its translational character.
76 citations
TL;DR: The significance of the partial oxygen pressure as an influential parameter during magnesium corrosion is pointed out, and a correlation could be established between DO consumption and areas of anodic and cathodic activity.
Abstract: The consumption of dissolved oxygen (DO) during the corrosion of commercially pure magnesium specimens was investigated by localized corrosion techniques The concentration of oxygen and the local current density on the near-surface of magnesium were measured simultaneously by a micro-optode DO sensor and the scanning vibrating electrode technique (SVET), respectively Diamond microelectrodes were also used for DO mapping Significant DO depletion was found since the initial immersion time of Mg in NaCl 05 m, and a correlation could be established between DO consumption and areas of anodic and cathodic activity These findings assume particular relevance for the corrosion of Mg alloys or magnesium components with impurity levels higher than the tolerance limit Moreover, this study points out the significance of the partial oxygen pressure as an influential parameter during magnesium corrosion
68 citations
TL;DR: It is demonstrated that the hydrogenation with para‐hydrogen of perdeuterated vinyl acetate allows us to create hyperpolarized ethyl acetate with close to 60 % 1H two‐spin order, which will open new opportunities to generate metabolic contrast agents in less than one minute.
Abstract: para-Hydrogen-induced polarization (PHIP) is a method to rapidly generate hyperpolarized compounds, enhancing the signal of nuclear magnetic resonance (NMR) experiments by several thousand-fold. The hyperpolarization of metabolites and their use as contrast agents in vivo is an emerging diagnostic technique. High degrees of polarization and extended polarization lifetime are necessary requirements for the detection of metabolites in vivo. Here, we present pulsed NMR methods for obtaining hyperpolarized magnetization in two metabolites. We demonstrate that the hydrogenation with para-hydrogen of perdeuterated vinyl acetate allows us to create hyperpolarized ethyl acetate with close to 60 % 1H two-spin order. With nearly 100 % efficiency, this order can either be transferred to 1H in-phase magnetization or 13C magnetization of the carbonyl function. Close to 60 % polarization is experimentally verified for both nuclei. Cleavage of the ethyl acetate precursor in a 20 s reaction yields ethanol with approximately 27 % 1H polarization and acetate with around 20 % 13C polarization. This development will open new opportunities to generate metabolic contrast agents in less than one minute.
56 citations
TL;DR: An updated bioeconomy perspective into a valued bioproduct (DHA), whose supply and production from glycerol, it is argued, will rapidly expand and diversify, with important global health benefits.
Abstract: Currently obtained from glycerol through microbial fermentation, the demand of 1,3-dihydroxyacetone (DHA) has significantly grown during the course of the last decade, driven by the consumer passion for a tan and increasing awareness of UV photodamage to the skin caused by prolonged exposure to the sun. We provide an updated bioeconomy perspective into a valued bioproduct (DHA), whose supply and production from glycerol, we argue in this study, will rapidly expand and diversify, with important global health benefits.
46 citations
TL;DR: A pulsed nuclear magnetic resonance (NMR) approach to generate hyperpolarized metabolites within seconds, which act as metabolism probes, by developing an isotopic labeling strategy for generating precursors containing a favorable nuclear spin system to add para‐hydrogen and convert its two‐spin longitudinal order into enhanced metabolite signals.
Abstract: Diseases such as Alzheimer's and cancer have been linked to metabolic dysfunctions, and further understanding of metabolic pathways raises hope to develop cures for such diseases. To broaden the knowledge of metabolisms in vitro and in vivo, methods are desirable for direct probing of metabolic function. Here, we are introducing a pulsed nuclear magnetic resonance (NMR) approach to generate hyperpolarized metabolites within seconds, which act as metabolism probes. Hyperpolarization represents a magnetic resonance technique to enhance signals by over 10 000-fold. We accomplished an efficient metabolite hyperpolarization by developing an isotopic labeling strategy for generating precursors containing a favorable nuclear spin system to add para-hydrogen and convert its two-spin longitudinal order into enhanced metabolite signals. The transfer is performed by an invented NMR experiment and 20 000-fold signal enhancements are achieved. Our technique provides a fast way of generating hyperpolarized metabolites by using para-hydrogen directly in a high magnetic field without the need for field cycling.
44 citations
TL;DR: This Minireview gives a brief overview of the recent advances and developments in the field of wearable chemosensors, summarizes the basic types of wearable Chemosensor, and discusses their main functions and fabrication methods.
Abstract: In recent years, there has been growing demand for wearable chemosensors for their important potential applications in mobile and electronic healthcare, patient self-assessment, human motion monitoring, and so on. Innovations in wearable chemosensors are revolutionizing the modern lifestyle, especially the involvement of both doctors and patients in the modern healthcare system. The facile interaction of wearable chemosensors with the human body makes them favorable and convenient tools for the detection and long-term monitoring of the chemical, biological, and physical status of the human body at a low cost with high performance. In this Minireview, we give a brief overview of the recent advances and developments in the field of wearable chemosensors, summarize the basic types of wearable chemosensors, and discuss their main functions and fabrication methods. At the end of this paper, the future development direction of wearable chemosensors is prospected. With continued interest and attention to this field, new exciting progress is expected in the development of innovative wearable chemosensors.
35 citations
TL;DR: A comprehensive analysis of recent examples reported in the field of quinoxaline‐based chromogenic and fluorogenic chemosensors for inorganic anions such as fluoride, cyanide, acetate, and phosphate as well as their utility in biomolecular science is provided.
Abstract: This Review article provides a comprehensive analysis of recent examples reported in the field of quinoxaline-based chromogenic and fluorogenic chemosensors for inorganic anions such as fluoride, cyanide, acetate, and phosphate, as well as their utility in biomolecular science. It commences with a discussion of the various structural motifs such as quinoxaline-based oligopyrroles, polymers, sulfonamides, cationic receptors, and miscellaneous receptors bearing mixed recognition sites in the same receptor. Advances are discussed in depth, where the focus of this review is to tackle mainly solution state anion sensing utilizing quinoxaline-based receptors using different spectroscopic techniques with reference to anion selectivity by colorimetric and fluorescence response. The various examples discussed in this Review illustrate how the integration of anion binding elements with the quinoxaline chromophore could result in anion responsive chemosensors. Over the years, it has been observed that structural modification of the quinoxaline moiety with different sets of signaling unit and recognition sites has resulted in a few anion specific chemosensors.
32 citations
TL;DR: The potential of using 19F‐containing ligands as future magnetic resonance imaging (MRI) contrast agents and as probes in magnetic resonance spectroscopy studies is illustrated by significantly increasing their magnetic resonance detectability through the signal amplification by reversible exchange (SABRE) hyperpolarization method.
Abstract: Fluorinated ligands have a variety of uses in chemistry and industry, but it is their medical applications as 18F-labelled positron emission tomography (PET) tracers where they are most visible. In this work, we illustrate the potential of using 19F-containing ligands as future magnetic resonance imaging (MRI) contrast agents and as probes in magnetic resonance spectroscopy studies by significantly increasing their magnetic resonance detectability through the signal amplification by reversible exchange (SABRE) hyperpolarization method. We achieve 19F SABRE polarization in a wide range of molecules, including those essential to medication, and analyze how their steric bulk, the substrate loading, polarization transfer field, pH, and rate of ligand exchange impact the efficiency of SABRE. We conclude by presenting 19F MRI results in phantoms, which demonstrate that many of these agents show great promise as future 19F MRI contrast agents for diagnostic investigations.
32 citations
TL;DR: The preparation of a three‐dimensional Si thin film negative electrode employing a porous Cu current collector resulted in an enhancement of both areal capacity and capacity retention in contrast with flat and rough current collectors that were prepared for comparison.
Abstract: This work reports the preparation of a three-dimensional Si thin film negative electrode employing a porous Cu current collector. A previously reported copper etching procedure was modified to develop the porous structures inside a 9 μm thick copper foil. Magnetron sputtering was used for the deposition of an n-type doped 400 nm thick amorphous Si thin film. Electrochemical cycling of the prepared anode confirmed the effectiveness of utilizing the approach. The designed Si thin film electrode retained a capacity of around 67 μAh cm-2 (1675 mAh g-1) in 100th cycle. The improved electrochemical performance resulted in an enhancement of both areal capacity and capacity retention in contrast with flat and rough current collectors that were prepared for comparison.
31 citations
TL;DR: A series of boronate ester fluorescence probes for the detection of hydrogen peroxide (H2O2) and the importance of an electron‐withdrawing or electron‐donating group in these systems is indicated.
Abstract: In this work, we synthesized a series of boronate ester fluorescence probes (E)-4,4,5,5-tetramethyl-2-(4-styrylphenyl)-1,3,2-dioxaborolane (STBPin), (E)-N,N-dimethyl-4-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)styryl)aniline (DSTBPin), (E)-4-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)styryl)benzonitrile (CSTBPin), (E)-2-(4-(4-methoxystyryl)phenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (MSTBPin), (E)-N,N-dimethyl-4-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)styryl)naphthalen-1-amine (NDSTBPin), and N,N-dimethyl-4-(2-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)oxazol-5-yl)aniline (DAPOX-BPin) for the detection of hydrogen peroxide (H2O2). DSTBPin and MSTBPin displayed an "Off-On" fluorescence response towards H2O2, owing to the loss of the intramolecular charge transfer (ICT) excited state. Whereas, CSTBPin displayed a decrease in fluorescence intensity in the presence of H2O2 owing to the introduction of an ICT excited state. STBPin, on the other hand, produced a small fluorescence decrease, indicating the importance of an electron-withdrawing or electron-donating group in these systems. Unfortunately, the longer wavelength probe, NDSTBPin, displayed a decrease in fluorescence intensity. Oxazole-based probe DAPOX-BPin produced a "turn-on" response. Regrettably, DAPOX-BPin required large concentrations of H2O2 (>3 mm) to produce noticeable changes in fluorescence intensity and, therefore, no change in fluorescence was observed in the cell imaging experiments.
29 citations
TL;DR: Chromo‐ and fluorogenic methods are an alternative to classical procedures for drug detection based on techniques that require large measurement times, the use of sophisticated equipment, and qualified personnel.
Abstract: The consumption of illicit drugs has increased exponentially in recent years and has become a problem that worries both governments and international institutions. The rapid emergence of new compounds, their easy access, the low levels at which these substances are able to produce an effect, and their short time of permanence in the organism make it necessary to develop highly rapid, easy, sensitive, and selective methods for their detection. Currently, the most widely used methods for drug detection are based on techniques that require large measurement times, the use of sophisticated equipment, and qualified personnel. Chromo- and fluorogenic methods are an alternative to those classical procedures.
TL;DR: Investigations showed that the AuNPs were monodispersed and spherically shaped with a size distribution over three groups, and UV/Vis spectroscopy revealed the maximum absorbance band of the AuPPs at λ=528 nm, which provided important insight into the formation/synthesis process of the auNPs.
Abstract: Herein, we report for the first time the successful preparation of a gold(III) nitrate [Au(NO3)3] water‐based precursor for use in a bottom‐up ultrasonic spray pyrolysis (USP) process. Due to its limited solubility in water, the precursor was prepared under reflux conditions with nitric acid (HNO3) as the solvent and ammonium hydroxide (NH4OH) as a neutralizer. This precursor enabled the USP synthesis of gold nanoparticles (AuNPs) and the in situ formation of low concentrations of NO2 − and NO3 − ions, which were caught directly in deionized water in a collection system. These ions were proven to act as stabilizers for the AuNPs. Investigations showed that the AuNPs were monodispersed and spherically shaped with a size distribution over three groups: the first contained 5.3 % AuNPs with diameters (2 r) 200 nm. UV/Vis spectroscopy revealed the maximum absorbance band of the AuNPs at λ=528 nm. Additionally, scanning transmission electron microscopy (STEM) observations of the smallest AuNPs (2 r<5 nm) revealed atomically resolved coalescence phenomena induced by interaction with the electron beam. Four stages of the particle‐growth process were distinguished: 1) movement and rotation of the AuNPs; 2) necking mechanism; 3) orientated attachment at matching facets; 4) reshaping of the AuNPs by surface diffusion. This provided important insight into the formation/synthesis process of the AuNPs.
TL;DR: A novel method for the formation of hollow Prussian blue analogue (CoFe–PBA) nanocubes, using spherical silica particles as sacrificial templates, which can offer a larger interfacial area between the electrolyte and the electrode, leading to an improvement in the electrochemical activity.
Abstract: Herein, we report a novel method for the formation of hollow Prussian blue analogue (CoFe-PBA) nanocubes, using spherical silica particles as sacrificial templates. In the first step, silica cores are coated by a CoFe-PBA shell and then removed by etching with hydrofluoric acid (HF). The cubic shape of CoFe-PBA is well-retained even after the removal of the silica cores, resulting in the formation of hollow CoFe-PBA cubes. The specific capacity of the hollow CoFe-PBA nanocubes electrodes is about two times higher than that of solid CoFe-PBA nanocubes as storage materials for sodium ions. Such an improvement in the electrochemical properties can be attributed to their hollow internal nanostructure. The hollow architecture can offer a larger interfacial area between the electrolyte and the electrode, leading to an improvement in the electrochemical activity. This strategy can be applied to develop PBAs with hollow interiors for a wide range of applications.
TL;DR: A series of sulfonic‐acid‐functionalized ionic liquid (IL)–heteropolyacid (HPA) hybrid catalysts are proposed for the conversion of glucose to HMF and it was found that water and heteropolyanions have a significant effect on the reaction kinetics.
Abstract: The effective dehydration of glucose to 5-hydroxymethylfurfural (HMF) has attracted increasing attention. Herein, a series of sulfonic-acid-functionalized ionic liquid (IL)-heteropolyacid (HPA) hybrid catalysts are proposed for the conversion of glucose to HMF. A maximum total yield of HMF and levoglucosan (LGA; ≈71 %) was achieved in the presence of pyrazine IL-HPA hybrid catalyst [PzS]H2PW in THF/H2O-NaCl (v/v 5:1). The mechanism of glucose dehydration was studied by tailoring the Bronsted/Lewis acid sites of the hybrid catalysts and altering the solvent composition. It was found that water and heteropolyanions have a significant effect on the reaction kinetics. Heteropolyanions are able to stabilize the intermediates and promote the direct dehydration of glucose and intermediate LGA to HMF. A small amount of water could facilitate the conversion of glucose to LGA and suppress the dehydration of LGA to levoglucosenone. In addition, the synergetic effect of Bronsted/Lewis acid sites and a little water was conducive to accelerated proton transfer, which improved the yield of HMF from glucose dehydration.
TL;DR: This versatile bilayer coating process enables reversible control over the colloidal stability of the metal oxide nanoparticles in fluorocarbons, hydrocarbons, and water and orthogonal tuning of the surface energies of nanoparticles via noncovalent interactions is accomplished.
Abstract: We describe a universal wet-chemical shell-by-shell coating procedure resulting in colloidal titanium dioxide (TiO2) and iron oxide (Fe3O4) nanoparticles with dynamically and reversibly tunable surface energies. A strong covalent surface functionalization is accomplished by using long-chained alkyl-, triethylenglycol-, and perfluoroalkylphosphonic acids, yielding highly stabilized core-shell nanoparticles with hydrophobic, hydrophilic, or superhydrophobic/fluorophilic surface characteristics. This covalent functionalization sequence is extended towards a second noncovalent attachment of tailor-made nonionic amphiphilic molecules to the pristine coated core-shell nanoparticles via solvophobic (i.e. either hydrophobic, lipophobic, or fluorophobic) interactions. Thereby, orthogonal tuning of the surface energies of nanoparticles via noncovalent interactions is accomplished. As a result, this versatile bilayer coating process enables reversible control over the colloidal stability of the metal oxide nanoparticles in fluorocarbons, hydrocarbons, and water.
TL;DR: Interestingly, the pyridine‐, indole‐, and pyrrole‐based curcumin derivatives demonstrated improved biological effects in terms of mitochondrial activity impairment and protein content, in addition to comparable or decreased antioxidant properties, as well as a desirable balance between good solubility and significant bioactivity.
Abstract: Curcumin, a natural compound extracted from the rhizomes of Curcuma longa, displays pronounced anticancer properties but lacks good bioavailability and stability. In a previous study, we initiated structure modification of the curcumin scaffold by imination of the labile β-diketone moiety to produce novel β-enaminone derivatives. These compounds showed promising properties for elaborate follow-up studies. In this work, we focused on another class of nitrogen-containing curcuminoids with a similar objective: to address the bioavailability and stability issues and to improve the biological activity of curcumin. This paper thus reports on the synthesis of new pyridine-, indole-, and pyrrole-based curcumin analogues (aza-aromatic curcuminoids) and discusses their water solubility, antioxidant activity, and antiproliferative properties. In addition, multivariate statistics, including hierarchical clustering analysis and principal component analysis, were performed on a broad set of nitrogen-containing curcuminoids. Compared to their respective mother structures, that is, curcumin and bisdemethoxycurcumin, all compounds, and especially the pyridin-3-yl β-enaminone analogues, showed better water solubility profiles. Interestingly, the pyridine-, indole-, and pyrrole-based curcumin derivatives demonstrated improved biological effects in terms of mitochondrial activity impairment and protein content, in addition to comparable or decreased antioxidant properties. Overall, the biologically active N-alkyl β-enaminone aza-aromatic curcuminoids were shown to offer a desirable balance between good solubility and significant bioactivity.
TL;DR: It is found that dienes with a terminal heteroatom, such as 2‐propen‐1‐imine (NCCC) or acrolein (OCCC), are less reactive than the archetypal 1,3‐butadiene (CCCC), primarily owing to weaker orbital interactions between the more electronegative heteroatoms with ethylene.
Abstract: We have quantum chemically explored the Diels-Alder reactivities of a systematic series of hetero-1,3-butadienes with ethylene by using density functional theory at the BP86/TZ2P level. Activation strain analyses provided physical insight into the factors controlling the relative cycloaddition reactivity of aza- and oxa-1,3-butadienes. We find that dienes with a terminal heteroatom, such as 2-propen-1-imine (NCCC) or acrolein (OCCC), are less reactive than the archetypal 1,3-butadiene (CCCC), primarily owing to weaker orbital interactions between the more electronegative heteroatoms with ethylene. Thus, the addition of a second heteroatom at the other terminal position (NCCN and OCCO) further reduces the reactivity. However, the introduction of a nitrogen atom in the backbone (CNCC) leads to enhanced reactivity, owing to less Pauli repulsion resulting from polarization of the diene HOMO in CNCC towards the nitrogen atom and away from the terminal carbon atom. The Diels-Alder reactions of ethenyl-diazene (NNCC) and 1,3-diaza-butadiene (NCNC), which contain heteroatoms at both the terminal and backbone positions, are much more reactive due to less activation strain compared to CCCC.
TL;DR: A three‐dimensional π‐conjugated chiral cage with six [5]helicene units (a triple helicene cage) was synthesized for the first time with unique structural features: a cage‐shaped rigid structure with outer helical grooves and an inner chiral cavity.
Abstract: A three-dimensional π-conjugated chiral cage with six [5]helicene units (a triple helicene cage) was synthesized for the first time. Taking advantage of the Yamamoto coupling reaction, the triflate-substituted triple [5]helicene, a strained and preorganized precursor, was dimerized to afford the target compound. Single-crystal X-ray diffraction analysis revealed the unique structural features of the triple helicene cage: a cage-shaped rigid structure with outer helical grooves and an inner chiral cavity. All-P and all-M enantiomers were separated successfully by HPLC over a chiral column and their chiroptical properties were characterized by circular dichroism spectra.
TL;DR: A simple one‐pot method for the rapid preparation of sub‐10 nm pure hexagonal (β‐phase) NaYF4‐based upconverting nanoparticles (UCNPs) using Therminol® 66 as a co‐solvent, monodisperse UCNPs could be obtained in unusually short reaction times.
Abstract: We report a simple one-pot method for the rapid preparation of sub-10nm pure hexagonal (-phase) NaYF4-based upconverting nanoparticles (UCNPs). Using Therminol((R))66 as a co-solvent, monodisperse UCNPs could be obtained in unusually short reaction times. By varying the reaction time and reaction temperature, it was possible to control precisely the particle size and crystalline phase of the UCNPs. The upconversion (UC) luminescence properties of the nanocrystals were tuned by varying the concentrations of the dopants (Nd3+ and Yb3+ sensitizer ions and Er3+ activator ions). The size and phase-purity of the as-synthesized core and core-shell nanocrystals were assessed by using complementary transmission electron microscopy, dynamic light scattering, X-ray diffraction, and small-angle X-ray scattering studies. In-depth photophysical evaluation of the UCNPs was pursued by using steady-state and time-resolved luminescence spectroscopy. An enhancement in the UC intensity was observed if the nanocrystals, doped with optimized concentrations of lanthanide sensitizer/activator ions, were further coated with an inert/active shell. This was attributed to the suppression of surface-related luminescence quenching effects.
TL;DR: These compounds act as heterogeneous catalysts for the nitroaldol and Knoevenagel condensation reactions of different aldehydes, and the most effective is zinc coordination polymer 1.
Abstract: The reactions of 3,3'-{(pyridine-2,6-dicarbonyl)bis(azanediyl)}dibenzoic acid (H2L) with zinc(II), cadmium(II), and samarium(III) nitrates were studied, and the obtained compounds, [Zn(1κO:2κO'-L)(H2O)2] n (1), [Cd(1κO2:2κO2-L)(H2O)2]2⋅6n H2O⋅n C4H8O2⋅1.5n DMF (2), and [Sm(1κO:2κO'O'':3κO'''-L)(NO3)(H2O)(dmf)] n⋅n DMF (3), were characterized by elemental analysis, FTIR spectroscopy, thermogravimetric analysis, and X-ray single-crystal diffraction. Compounds 1 and 3 have 1D zigzag- and double-chain-type structures, respectively, whereas 2 features a dinuclear metallomacrocyclic complex. The ligand (L2-) orients in different conformations, that is, syn-syn for 1 and anti-anti for 2 and 3. Compound 1 is the first example in which the syn-syn conformation for this ligand has been observed. These compounds act as heterogeneous catalysts for the nitroaldol (Henry; in water medium) and Knoevenagel condensation reactions of different aldehydes, and the most effective is zinc coordination polymer 1. Recyclability, heterogeneity, and size-selectivity tests were performed, which showed that the catalyst was highly active over at least four recycling runs.
TL;DR: In this paper, the authors reported the successful electrochemical fluorination and defluorination of schafarzikite-type compounds with the composition Fe0.5 m 0.5Sb2O4 (M=Mg or Co) and showed that electrochemical methods can present a controllable and less environmentally damaging route for fluorinating compounds in contrast to traditional methods that involve heating samples in F2-rich atmospheres.
Abstract: Herein, we report the successful electrochemical fluorination and defluorination of schafarzikite-type compounds with the composition Fe0.5 m 0.5Sb2O4 (M=Mg or Co). We show that electrochemical methods can present a more controllable and less environmentally damaging route for fluorinating compounds in contrast to traditional methods that involve heating samples in F2-rich atmospheres. The reactivity of the host lattices with fluoride during electrochemical fluorination makes this material an interesting candidate for fluoride-ion battery applications. However, deleterious side reactions with the conductive carbon matrix during fluorination suggests to the contrary. Regardless of the side reactions, the schafarzikite structure was found to be an alternative reversible host lattice for fluoride incorporation and removal in addition to the previously reported Ruddlesden-Popper-type compounds.
TL;DR: Detailed materials characterization reveals that, although the mesopore dimensions are modified by the identity of the sugar template, the desirable acid characteristics of the microporous framework are retained.
Abstract: In a distinct, bottom-up synthetic methodology, monosaccharides (fructose and glucose) and disaccharides (sucrose) have been used as mesoporogens to template hierarchical SAPO-34 catalysts. Detailed materials characterization, which includes solid-state magic angle spinning NMR and probe-based FTIR, reveals that, although the mesopore dimensions are modified by the identity of the sugar template, the desirable acid characteristics of the microporous framework are retained. When the activity of the hierarchical SAPO-34 catalysts was evaluated in the industrially relevant Beckmann rearrangement, under liquid-phase conditions, the enhanced mass-transport properties of sucrose-templated hierarchical SAPO-34 were found to deliver a superior yield of ϵ-caprolactam.
TL;DR: This Review discusses what is currently known from the literature about the interaction of gluten with the gut and the critical host responses it evokes and connects them to the current and novel molecular understanding of the supramolecular organization ofgliadin and the 33‐mer gliadin peptide fragment under physiological conditions.
Abstract: Gluten‐related disorders are a complex group of diseases that involve the activation of the immune system triggered by the ingestion of gluten. Among these, celiac disease, with a prevalence of 1 %, is the most investigated, but recently, a new pathology, named nonceliac gluten sensitivity, was reported with a general prevalence of 7 %. Finally, there other less‐prevalent gluten‐related diseases such as wheat allergy, gluten ataxia, and dermatitis herpetiformis (with an overall prevalence of less than 0.1 %). As mentioned, the common molecular trigger is gluten, a complex mixture of storage proteins present in wheat, barley, and a variety of oats that are not fully degraded by humans. The most‐studied protein related to disease is gliadin, present in wheat, which possesses in its sequence many pathological fragments. Despite a lot of effort to treat these disorders, the only effective method is a long‐life gluten‐free diet. This Review summarizes the actual knowledge of gluten‐related disorders from a translational chemistry point of view. We discuss what is currently known from the literature about the interaction of gluten with the gut and the critical host responses it evokes and, finally, connect them to our current and novel molecular understanding of the supramolecular organization of gliadin and the 33‐mer gliadin peptide fragment under physiological conditions.
TL;DR: In this paper, 1H-NMR chemical shift DFT calculations were carried out in DMSO solution using the polarizable continuum model (PCM) to simulate the solvent effect.
Abstract: As the knowledge of the predominant molecular structure of antioxidant and anticancer flavonoid rutin in solution is very important for understanding the mechanism of action, a quantum chemical investigation of plausible rutin structures including solvent effects is of relevance. In this work, DFT calculations were performed to find possible minimum energy structures for the rutin molecule. 1H NMR chemical shift DFT calculations were carried out in DMSO solution using the polarizable continuum model (PCM) to simulate the solvent effect. Analysis of the experimental and theoretical 1H NMR chemical shift profiles offers a powerful fingerprint criterion to determine the predominant molecular structure in solution. Therefore, our aim is to find the best match between experimental (in DMSO-d) and theoretical (PCM-DMSO) 1H NMR spectrum profiles. Among 34 optimized structures located on the potential energy surface, we found that structure 32, with a B-ring deviated 30° from a planar configuration (geometry usually assumed for polyphenols), showed an almost perfect agreement with experimental the 1H NMR pattern when compared to the corresponding fully optimized planar geometry. This structure is also predicted as the global minimum based on room-temperature Gibbs free energy calculations in solution and, therefore, should be experimentally observed. This is new and valuable structural information regarding structure-activity relationship studies, and such information is hard to obtain by experimentalists without the aid of the X-ray diffraction technique.
TL;DR: It is shown that, for SP NTs, a much higher photocatalytic performance can be achieved with significantly smaller Pt nanoparticles (i.e. for fewer ALD cycles) compared to CP NTs.
Abstract: In the present work, we report the use of TiO2 nanotube (NT) layers with a regular intertube spacing that are decorated by Pt nanoparticles through the atomic layer deposition (ALD) of Pt. These Pt-decorated spaced (SP) TiO2 NTs are subsequently explored for photocatalytic H2 evolution and are compared to classical close-packed (CP) TiO2 NTs that are also decorated with various amounts of Pt by using ALD. On both tube types, by varying the number of ALD cycles, Pt nanoparticles of different sizes and areal densities are formed, uniformly decorating the inner and outer walls from tube top to tube bottom. The photocatalytic activity for H2 evolution strongly depends on the size and density of Pt nanoparticles, driven by the number of ALD cycles. We show that, for SP NTs, a much higher photocatalytic performance can be achieved with significantly smaller Pt nanoparticles (i.e. for fewer ALD cycles) compared to CP NTs.
TL;DR: Facile intramolecular amination of unactivated alkenes has been achieved by using electricity as a catalyst that helps to generate an intermediate and accelerates formation of cyclic ureas in high yields using TEMPO.
Abstract: Facile intramolecular amination of unactivated alkenes has been achieved by using electricity as a catalyst that helps to generate an intermediate and accelerates formation of cyclic ureas in high yields. Using this method, no metal catalysts were used. During electrolysis, a nitrogen radical was formed at the urea substrate that cyclised with the alkene and generated a terminal carbon radical which further formed a bond with the 2,2,6,6-tetramethylpiperidine-N-oxyl radical (TEMPO). This method of electrolysis not only gives cyclic ureas but also functionalises terminal unactivated alkenes. This method can be considered to be environmentally friendly given that it avoids the issues of toxicity or complicated metal ligands and could therefore be potentially employed in green chemistry.
TL;DR: A novel method to monitor the real‐time activity of bacterial growth at the single‐cell level inside giant unilamellar vesicles (GUVs), which protected the bacteria from external antibiotic compounds during prolonged cultivation for more than 24 h.
Abstract: Invited for this month's cover picture are Dr. Masamune Morita, Dr. Kaoru Katoh and Dr. Naohiro Noda from the Biomedical Research Institute at the National Institute of Advanced Industrial Science and Technology (AIST, Japan). The cover picture shows direct monitoring of real-time activity of bacterial growth at the single-cell level inside giant unilamellar vesicles (GUVs); entrapped single bacterial cells are actively increasing to a great number of cells inside GUVs. This study shows new applications for GUVs, and can offer a novel tool for culturing bacteria in bacterial studies. Read the full text of their Communication at https://doi.org/10.1002/open.201800126.
TL;DR: Dendritic fibrous nanosilica (DFNS) with a high surface area is successfully employed as a template to synthesize DFNS/Au hybrid nanomaterials, which are highly applicable in a variety of areas.
Abstract: Morphologically unique silica nanoparticles can be used as effective templates to prepare silica-metal hybrid nanomaterials, which are highly applicable in a variety of areas. Mesoporous silica nanoparticles, which have high surface areas and an abundance of pores, can be used to synthesize mesoporous silica core-metal shell nanostructures with catalytically active sites. In this work, dendritic fibrous nanosilica (DFNS) with a high surface area is successfully employed as a template to synthesize DFNS/Au hybrid nanomaterials. Au nanodots are initially synthesized through the selective reduction of Au ions on the surface of the DFNS after surface modification to form DFNS/Au dots. A seed-mediated growth method is used to controllably grow Au nanoparticles on the DFNS/Au dots to generate DFNS core-Au nanoparticles shell nanohybrids (DFNS/Au NPs) and DFNS core-Au layer shell nanohybrids (DFNS/Au layers). The catalytic activities of DFNS/Au NPs and DFNS/Au layers in the 4-nitrophenol reduction reaction are compared.
TL;DR: Interestingly, the trifluoromethanesulfonylation of unsymmetrical benzyne precursors proceeded smoothly to furnish corresponding aryl triflones in good yields with good to high regioselectivities.
Abstract: The direct synthesis of aryl triflones, that is, trifluoromethanesulfonyl arenes, was achieved through the trifluoromethanesulfonylation of benzynes. The trifluoromethanesulfonyl group, one of the fluorinated functional groups, is a highly electron-negative and mild lipophilic substituent. Aryl triflones have high potential in the synthesis of bioactive compounds and specialty materials. The treatment of 2-(trimethylsilyl)aryl trifluoromethanesulfonates with cesium fluoride in the presence of 15-crown-5 generated benzynes, which reacted with sodium trifluoromethanesulfinate followed by protonation with tBuOH under heating conditions, provided aryl triflones in moderated to good yields. Both symmetrical and unsymmetrical triflones were nicely accessed under the same reaction conditions. Interestingly, the trifluoromethanesulfonylation of unsymmetrical benzyne precursors proceeded smoothly to furnish corresponding aryl triflones in good yields with good to high regioselectivities. The balance of polarization of electric charge as well as steric hindrance of the benzyne intermediates are central factors to control the outcome of regioselectivity.
TL;DR: This Minireview presents recent advances in the chemistry of phthalans and coumarans, with the goal of overcoming synthetic challenges and facilitating the applications of Phthalan and Coumarans.
Abstract: Oxygen-containing heterocycles are common in biologically active compounds. In particular, phthalan and coumaran cores are found in pharmaceuticals, organic electronics, and other useful medical and technological applications. Recent research has expanded the methods available for their synthesis. This Minireview presents recent advances in the chemistry of phthalans and coumarans, with the goal of overcoming synthetic challenges and facilitating the applications of phthalans and coumarans.