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Many biomedical fields rely on proteins that are selectively modified. These can be attached using reactive or catalytic moieties, but the position where these moieties are attached is often poorly controlled. We assessed how catalyst position affects the efficiency and selectivity of protein modification. For this, we anchored a template DNA strand to three different proteins, which were subsequently hybridized to DNA strands that contained catalysts at different positions. We found a strong correlation between the catalyst‐to‐protein distance and the efficiency of protein modification for acyl transfer catalysts, which operate via a covalently bound reactant intermediate. Additionally, we found that the catalyst's distance and orientation with respect to the protein surface, also influences its site‐selectivity. A catalyst operating with unbound reactant intermediates showed only enhanced efficiency. Our results are rationalized using computational simulations, showing that one‐point anchoring of the DNA construct leads to notable differences in the site of modification. [ABSTRACT FROM AUTHOR]

Surface functionalization of inorganic semiconductor substrates, particularly silicon, has focused attention toward many technologically important applications, involving photovoltaic energy, biosensing and catalysis. For such modification processes, oxide-free (H-terminated) silicon surfaces are highly required, and different chemical approaches have been described in the past decades. However, their reactivity is often poor, requiring long reaction times (2-18 h) or the use of UV light (10-30 min). Here, we report a simple and rapid surface functionalization for H-terminated Si(111) surfaces using alkyl silanols. This catalyst-free surface reaction is fast (15 min at room temperature) and can be accelerated with UV light irradiation, reducing the reaction time to 1-2 min. This grafting procedure leads to densely packed organic monolayers that are hydrolytically stable (even up to 30 days at pH 3 or 11) and can display excellent antifouling behavior against a range of organic polymers. [ABSTRACT FROM AUTHOR]

A simplified coupling of surface plasmon resonance (SPR) immuno-biosensing with ambient ionization mass spectrometry (MS) was developed. It combines two orthogonal analysis techniques: the biosensing capability of SPR and the chemical identification power of high resolution MS. As a proof-of-principle, deoxynivalenol (DON), an important mycotoxin, was captured using an SPR gold chip containing an antifouling layer and monoclonal antibodies against the toxin and, after washing, the chip could be taken out and analyzed by direct spray MS of the biosensor chip to confirm the identity of DON. Furthermore, cross-reacting conjugates of DON present in a naturally contaminated beer could be successfully identified, thus showing the potential of rapid identification of (un)expected cross-reacting molecules. [ABSTRACT FROM AUTHOR]

This review discusses the advances in metabolic oligosaccharide engineering (MOE) from 2010 to 2016 with a focus on the structure, preparation, and reactivity of its chemical probes. A brief historical overview of MOE is followed by a comprehensive overview of the chemical probes currently available in the MOE molecular toolbox and the bioconjugation techniques they enable. The final part of the review focusses on the synthesis of a selection of probes and finishes with an outlook on recent and potential upcoming advances in the field of MOE. [ABSTRACT FROM AUTHOR]

Superhydrophobic surfaces with micro/nanostructures are widely used to prevent nonspecific adsorption of commercial polymeric and/or biological materials. Herein, a self-healing superhydrophobic and highly protein-repellent fluoropolymer brush was grafted onto nanostructured silicon by surface-initiated atom transfer radical polymerization (ATRP). Both the superhydrophobicity and antifouling properties (as indicated for isolated protein solutions and for 10% blood plasma) are well repaired upon serious chemical degradation (by e.g. air plasma). This brush still maintains excellent superhydrophobicity and good antifouling properties even after 5 damage-repair cycles, which opens a new door to fabricate long-term antifouling coatings on various substrates that can be used in harsh environments. [ABSTRACT FROM AUTHOR]

The use of microreactor technology for the ring-opening polymerization of l-lactide catalyzed by 1,5,7-triazabicyclo[4.4.0]dec-5-ene allows for rapid optimization of reaction parameters (reaction temperature and residence time). At moderate catalyst loading, good control over the polymerization is demonstrated by high conversion of monomer (>95%) and low polydispersity (<1.3) at residence times as low as 2 s. This metal-free, organocatalytic route yields well-defined poly(lactic acid) in continuous flow and by using bicyclononyne- and tetrazine-containing initiators gives access to poly(lactic acid) amenable to click chemistry. [ABSTRACT FROM AUTHOR]

Reaction rates of strained cycloalkynes and cycloalkenes with 1,2‐quinone were quantified by stopped flow UV‐Vis spectroscopy and computational analysis. We found that the strained alkyne BCN−OH 3 (k2 1824 M−1 s−1) reacts >150 times faster than the strained alkene TCO‐OH 5 (k2 11.56 M−1 s−1), and that derivatization with a carbamate can lead to a reduction of the rate constant with almost half. Also, the 8‐membered strained alkyne BCN−OH 3 reacts 16 times faster than the more strained 7‐membered THS 2 (k2 110.6 M−1 s−1). Using the linearized Eyring equation we determined the thermodynamic activation parameters of these two strained alkynes, revealing that the SPOCQ reaction of quinone 1 with THS 2 is associated with ΔH≠ of 0.80 kcal/mol, ΔS≠=−46.8 cal/K⋅mol, and ΔG≠=14.8 kcal/mol (at 25 °C), whereas the same reaction with BCN−OH 3 is associated with, ΔH≠=2.25 kcal/mol, ΔS≠=−36.3 cal/K⋅mol, and ΔG≠=13.1 kcal/mol (at 25 °C). Computational analysis supported the values obtained by the stopped‐flow measurements, with calculated ΔG≠ of 15.6 kcal/mol (in H2O) for the SPOCQ reaction with THS 2, and with ΔG≠ of 14.7 kcal/mol (in H2O) for the SPOCQ reaction with BCN−OH 3. With these empirically determined thermodynamic parameters, we set an important step towards a more fundamental understanding of this set of rapid click reactions. [ABSTRACT FROM AUTHOR]

Highlights: [•] Covalently bound organic monolayers on Si decrease wear scratches by factor 120. [•] AFM studies show that for normal loads <8μN almost no wear marks are observed. [•] The high bond strength of the new Si C C linker is the main cause. [•] Fluorination of the monolayer and the high monolayer density are also crucial. [•] These results open up new applications of Si-based NEMS/MEMS. [Copyright &y& Elsevier]

In this work, we tuned the ion selectivity of a polyelectrolyte multilayer (PEM)-coated, cation-exchange membrane (CMX) in a membrane capacitive deionization (MCDI) process by carefully studying different operational modes, namely constant voltage (CV) and constant current (CC). The monovalent cation selectivity and its time-dependent behavior were monitored at different voltage and current values. Upon optimizing the current density (10 A/m2) and the number of polyelectrolyte bilayers (5.5) on the CMX membranes, a time-independent and nearly full monovalent cation selectivity was obtained for various feed solutions, provided a polycation-terminated PEM was applied. Furthermore, the selectivity values of several commercially available cation-exchange membranes were tested under the optimized conditions and compared with CMX and PEM-CMX, yielding the best performance for PEM-CMX, regardless the composition of feed solution. Before this optimization, this MCDI system showed a time-dependent selectivity, with a maximum of ρ Mg Na ≈3. The results were rationalized by applying an MCDI model based on the dynamic potential profile, describing the potential drops across the membrane and demonstrating a threshold for the current density. [Display omitted] • Ion selectivity of MCDI boosted by optimizing operational conditions • Focus on monovalent cation selectivity of a polyelectrolyte multilayer-coated membrane • Comparison of constant current (CC) and constant voltage (CV) modes • Time-independent, enhanced monovalent cation selectivity achieved • Selectivity rationalized by using a model based on the dynamic potential profile [ABSTRACT FROM AUTHOR]

Covalently attached organic layers on indium tin oxide(ITO) surfaceswere prepared by the photochemical grafting with 1-alkenes. The surfacemodification was monitored with static water contact angle, X-rayphotoelectron spectroscopy (XPS), and atomic force microscopy (AFM)measurements. Hydrophobic methyl-terminated ITO surfaces can be obtainedvia the grafting of tetradec-1-ene, whereas the attachment of ω-functionalized1-alkenes leads to functionalized ITO surfaces. The use of a CCGe(CH3)3terminus allows for facile tagging of the surfacewith an azido group via a one-pot deprotection/click reaction, resultingin bio/electronically active interfaces. The combination of nonaggressivechemicals (alkenes), mild reaction conditions (room temperature),and a light-induced grafting that facilitates the direct patterningof organic layers makes this simple approach highly promising forthe development of ITO-based (bio)electronic devices. [ABSTRACT FROM AUTHOR]

1-O-Pivaloyl glycosides were shown to be efficient glycosyl donors by using the perpivaloylated derivatives of lactose, galactose and glucose in the direct ZnCl2-promoted glycosylations of various alcohols. The corresponding glycosides were isolated in good yields and β-selectivity. [ABSTRACT FROM AUTHOR]

The mechanism of the formation of Si−C bonded monolayers on silicon by reaction of 1-alkenes with hydrogen-terminated porous silicon surfaces has been studied by both experimental and computational means. We propose that monolayer formation occurs via the same radical chain process as at single-crystal surfaces: a silyl radical attacks the 1-alkene to form both the Si−C bond and a radical center on the β-carbon atom. This carbon radical may then abstract a hydrogen atom from a neighboring Si−H bond to propagate the chain. Highly deuterated porous silicon and FTIR spectroscopy were used to provide evidence for this mechanism by identifying the IR bands associated with the C−D bond formed in the proposed propagation step. Deuterated porous silicon surfaces formed by galvanostatic etching in 48% DF/D2O:EtOD (1:1) electrolytes showed a 30% greater density of Si−D sites on the surface than Si−H sites on hydrogen-terminated porous silicon surfaces prepared in the equivalent H-electrolyte. The thermal reaction of undec-1-ene and the Lewis acid catalyzed reaction of styrene on a deuterated surface both resulted in alkylated surfaces with the same C−C and C−H vibrational features as formed in the corresponding reactions at a hydrogen-terminated surface. However, a broad band around 2100 cm-1 was observed upon alkylating the deuterated surfaces. Ab initio and density functional theory calculations on small molecule models showed that the integrated absorbance of this band was comparable to the intensity expected for the C−D stretches predicted by the chain mechanism. The calculations also indicate that there is substantial interaction between the hydrogen atoms on the β-carbons and the hydrogen atoms on the Si(111)−H surface. These broad 2100 cm-1 features are therefore assigned to C−D bands arising from the involvement of surface D atoms in the hydrosilylation reactions, while the line broadening can be explained partly by interaction with neighboring surface atoms/groups. [ABSTRACT FROM AUTHOR]

The photochemistry of (E)-bromostyrene was investigated to determine the nature of the productforming intermediates and to clarify the mechanism of formation of vinylic cations and vinylic radicals. Both a cation- and a radical-derived product are formed, and the ionic origin of the former product is demonstrated by significant scrambling of the label, starting from specifically deuterated (E)-bromostyrene. MO calculations show that the isolated incipient primary vinyl cation is not a metastable species, but that specific interaction with a counterion in combination with a polar environment makes it metastable. The effects of variation of the wavelength of irradiation, solvent polarity, temperature, and isotopic substitution all agree with a mechanism of direct heterolytic C-Br bond cleavage producing an ion pair followed by formation of a radical pair via electron transfer. The vinylic cation is proposed to stem directly from the indirectly populated lowest excited singlet state of bromostyrene with an energy of activation of 6.7 kcal/mol. Branching between proton loss and electron transfer in the resulting ion pair determines the ratio of cation- to radical-derived product. The E/Z-isomerization occurs in a separate process and does not involve C-Br bond cleavage. [ABSTRACT FROM AUTHOR]

Alkenes are known to react with hydrogen-terminated silicon surfaces to produce robust organic monolayers that are attached to the surface via covalent Si&z.sbnd;C bonds. In this report we investigate the dependence of the rate of alkylation of porous silicon samples on the reaction time using photochemical initiation. The kinetics of the photochemical alkylation of hydrogen-terminated porous silicon by undec-1-ene in toluene were observed to be pseudo first order, however the apparent rate constant decreased as the concentration of undec-1-ene increased. This behaviour is opposite to what would be expected if the rate-limiting process was an elementary chemical reaction step involving the alkene. Instead, it suggests that transport of the alkene to reactive sites and in the correct orientation is the rate-limiting step. Comparison of the rates of alkylation of porous silicon by undec-1-ene and dimethoxytrityl (DMT)–undecenol is consistent with such an interpretation as the bulky DMT headgroup gives a lower rate of alkylation. The diffusion of some simple redox-active probe molecules in porous silicon was investigated using a scanning electrochemical microscope (SECM). The probe molecules are converted at diffusion-controlled rate at an inlaid disk ultramicroelectrode (UME) consisting of the cross-section of a microwire sealed in glass. If the microelectrode is placed a short distance above the porous silicon, the microelectrode current depends on kinetics of the electrochemical reactions at the porous silicon and the mass transport properties within the open thin layer cell formed by the microelectrode and the alkylated porous silicon. In order to differentiate the effects of finite heterogeneous kinetics at silicon from diffusion limitations, current–distance curves were fitted over a wide range of applied potentials (on the Si) and it was observed that the diffusion coefficient in the porous layer was strongly anisotropic. The measured diffusion rates are comparable to those in bulk water along the pores, but with negligible diffusion between pores. This indicates that few pore–pore interconnections exist in the porous silicon. [Copyright &y& Elsevier]

As the core component of sandwich‐like perovskite solar cells (PSCs), the quality of perovskite layer is a challenge for further progress in PSCs due to the unfavorable defects and uncontrollable crystallization. Here, a surface post‐treatment strategy employing ethyl thioglycolate (ET) as ligand molecule is developed for property manipulation of perovskite films. ET can lower surface energy of perovskite facets and induces secondary growth of grains, giving films with higher crystallinity and lower defect density. Meanwhile, both carbonyl and sulfhydryl in ET can bind to the Pb2+, thus forming bidentate anchoring on the surface for defect passivation. Besides, the perovskite/ET/C60 interface presents improved charge transfer owing to the well‐aligned energy levels. Consequently, the power‐conversion‐efficiency (PCE) is boosted to 22.42% and 23.56% (certified 23.29%) for the FA0.85Cs0.15Pb(I0.95Br0.05)3 and FA0.9MA0.05Cs0.05Pb(I0.95Br0.05)3 PSCs, respectively, and the FA0.85Cs0.15Pb(I0.95Br0.05)3‐based PSC with a larger area (1.03 cm2) delivers a PCE of 20.01%. Importantly, ET demonstrates effective management of I2 and PbI2, thereby preventing accelerated degradation and lead leakage of devices. Thanks to the multiple effects of ET, the resulting devices exhibit significantly enhanced ambient stability over a course of 800 h, and a thermal stability of over 1500 h while maintaining 80.4% of its original efficiency. [ABSTRACT FROM AUTHOR]

Per‐ and polyfluoroalkyl substances (PFAS) pose a rapidly increasing global problem as their widespread use and high stability lead worldwide to water contamination, with significant detrimental health effects.[1] Supramolecular chemistry has been invoked to develop materials geared towards the specific capture of PFAS from water,[2] to reduce the concentration below advisory safety limits (e.g. 70 ng/L for the sum of perfluorooctane sulfonic acid, PFOS and perfluorooctanoic acid, PFOA). Scale‐up and use in natural waters with high PFAS concentrations has hitherto posed a problem. Here we report a new type of host–guest interaction between deca‐ammonium‐functionalized pillar[5]arenes (DAF−P5s) and perfluoroalkyl acids. DAF−P5 complexes show an unprecedented 1 : 10 stoichiometry, as confirmed by isothermal calorimetry and X‐ray crystallographic studies, and high binding constants (up to 106 M−1) to various polyfluoroalkyl acids. In addition, non‐fluorinated acids do not hamper this process significantly. Immobilization of DAF−P5s allows a simple single‐time filtration of PFAS‐contaminated water to reduce the PFOS/PFOA concentration 106 times to 15–50 ng/L level. The effective and fast (<5 min) orthogonal binding to organic molecules without involvement of fluorinated supramolecular hosts, high breakthrough capacity (90 mg/g), and robust performance (>10 regeneration cycles without decrease in performance) set a new benchmark in PFAS‐absorbing materials. [ABSTRACT FROM AUTHOR]

Per‐ and polyfluoroalkyl substances (PFAS) pose a rapidly increasing global problem as their widespread use and high stability lead worldwide to water contamination, with significant detrimental health effects.[1] Supramolecular chemistry has been invoked to develop materials geared towards the specific capture of PFAS from water,[2] to reduce the concentration below advisory safety limits (e.g. 70 ng/L for the sum of perfluorooctane sulfonic acid, PFOS and perfluorooctanoic acid, PFOA). Scale‐up and use in natural waters with high PFAS concentrations has hitherto posed a problem. Here we report a new type of host–guest interaction between deca‐ammonium‐functionalized pillar[5]arenes (DAF−P5s) and perfluoroalkyl acids. DAF−P5 complexes show an unprecedented 1 : 10 stoichiometry, as confirmed by isothermal calorimetry and X‐ray crystallographic studies, and high binding constants (up to 106 M−1) to various polyfluoroalkyl acids. In addition, non‐fluorinated acids do not hamper this process significantly. Immobilization of DAF−P5s allows a simple single‐time filtration of PFAS‐contaminated water to reduce the PFOS/PFOA concentration 106 times to 15–50 ng/L level. The effective and fast (<5 min) orthogonal binding to organic molecules without involvement of fluorinated supramolecular hosts, high breakthrough capacity (90 mg/g), and robust performance (>10 regeneration cycles without decrease in performance) set a new benchmark in PFAS‐absorbing materials. [ABSTRACT FROM AUTHOR]

Compares the (+)-catechin transglucosylating activities of several glucosyltransferases (GTF) from the genus Streptococcus. Methods of enzymatic glucosylation; Applications of catechin; Glucan production from dietary sucrose by GTF; Transglucosylation of catechin by GTF-D; Influence of fructose on GTF-D tranglucosylation activity.

Presents a study on carbon-oxygen hydrogen bonding in dehydrohalogenation reactions. Introduction to the study; Theoretical methodology used to carry out the study; Discussion and results of the study.

Studies the photochemical reactions in methanol of the vinylic halides 2-halo-1-phenyl-1,3-butadienes (beta-halo-beta-alkenylstyrenes) and 1-halo-1,2-diphenylethenes (alpha-halostilbenes). Analyses of various primary reactions; Ionic species as vinyl cation and halide ion pairs.

The imine bond is among the most applied motifs in dynamic covalent chemistry. Although its uses are varied and often involve coordination to a transition metal for stability, mechanistic studies on imine exchange reactions so far have not included metal coordination. Herein, we investigated the condensation and transimination reactions of an Fe2+‐coordinated diimine pyridine pincer, employing wB97XD/6‐311G(2d,2p) DFT calculations in acetonitrile. We first experimentally confirmed that Fe2+ is strongly coordinated by these pincers, and is thus a justified model ion. When considering a four‐membered ring‐shaped transition state for proton transfers, the required activation energies for condensation and transimination reaction exceeded the values expected for reactions known to be spontaneous at room temperature. The nature of the incoming and exiting amines and the substituents on the para‐position of the pincer had no effect on this. Replacing Fe2+ with Zn2+ or removing it altogether did not reduce it either. However, the addition of two ethylamine molecules lowered the energy barriers to be compatible with experiment (19.4 and 23.2 kcal/mol for condensation and transimination, respectively). Lastly, the energy barrier of condensation of a non‐coordinated pincer was significantly higher than found for Fe2+‐coordinating pincers, underlining the catalyzing effect of metal coordination on imine exchange reactions. [ABSTRACT FROM AUTHOR]

The mechanical properties of imine-based covalent adaptable networks can be enhanced by introduction of internal hydrogen bonding inside the polymer network. [Display omitted] • Integration of –rationally designed– internal hydrogen-bonding motifs inside imine-based covalent adaptable networks. • Molecular-level control over macroscopic material properties. • Improved creep resistance due to internal hydrogen-bonding. • Overall enhanced material performance (as expressed in T g , G' , E act and solvent resistance) due to internal hydrogen-bonding. Covalent Adaptable Networks (CANs) have the potential to replace current thermoset materials, as the dynamic covalent bonds in CANs enable reprocessability and recycling of crosslinked polymer networks. A current limitation of CANs is, however, that they are generally susceptible towards creep, as the bond exchange reactions facilitate stress relaxation. In this work, we propose the use of internal hydrogen bonding in polyimine CANs as an efficient tool to enhance creep resistance (at operating temperature) and further control the dynamic mechanical properties, while still enabling malleability at elevated temperatures. We are able to show on a small-molecule level that ortho -substituted hydroxy groups on aromatic imines stabilise the dynamic covalent imine bonds as a result of the internal hydrogen bond that is formed between the hydroxy and imine group. Furthermore, we show that polyimine CANs with incorporated ortho hydroxy groups have significantly enhanced material properties, as can be seen in the glass transition temperature (T g), elastic modulus (G '), creep resistance and solvent resistance. While we also consider additional steric and electronic effects that might have arisen due to installation of the hydroxy groups, we find that the stabilising effect of the internal hydrogen bond is primarily dictating the material performance. [ABSTRACT FROM AUTHOR]

As acetonitrile is a widely used solvent for the chemical industry, the recovery of acetonitrile from acetonitrile wastewater is significant for both industrial cost reduction and environmental protection. In this article, a simple, low‐energy, and low‐cost strategy is proposed for the effective separation of acetonitrile from high‐concentration acetonitrile wastewater. The approach is based on a sequential combination of two steps: salt‐induced phase separation and hydrophobic filtration. The acetonitrile wastewater was first induced to split into two phases by salt, that is, the acetonitrile‐rich phase and the water‐rich phase, then the above two phases were poured into the hydrophobic filter paper funnel for the separation. It was shown that NaCl is a suitable salting‐out reagent, and that hydrophobic filter papers—obtained from modification by butyltrichlorosilane and octyltrichlorosilane were the optimal choice for hydrophobic filtration. The salt‐induced phase separation process is able to increase the volume fraction of acetonitrile in the acetonitrile‐rich phase up to 92%. The acetonitrile‐rich phase can pass through the hydrophobic filter paper, whereas the water‐rich phase was intercepted. The hydrophobic filter paper retained strong hydrophobicity and high acetonitrile‐separating capacity after 3 months storage, or upon immersion in acetonitrile‐water mixtures for 12 h, or applied for 25 consecutive separations. [ABSTRACT FROM AUTHOR]

We developed an improved, robust synthesis of a series of pillar[6]arenes with a varying number (0–3) of quinone moieties in the ring. This easy-to-control variation yielded a gradually less electron-rich cavity in going from zero to three quinone units, as shown from the strength of host–guest interactions with silver ions. Such macrocycle-Ag2 complexes themselves were shown to display an unprecedented, sharp distinction between terminal alkynes, which strongly bound to such complexes, and internal alkynes, internal alkenes and terminal alkenes, which do hardly bind. [ABSTRACT FROM AUTHOR]

The nitrone (I) is found to be optimal for the title reactions. [ABSTRACT FROM AUTHOR]

Singlet fission is one of the most promising routes to overcome the single-junction efficiency limit for solar cells. Singlet fission-enhanced silicon solar cells are the most desirable implementation, but transfer of triplet excitons, the product of singlet fission, into silicon solar cells has proved to be very challenging. Here, we report on an all optical measurement technique for the detection of triplet exciton quenching at semiconductor interfaces, a necessary requirement for triplet exciton or charge transfer. The method relies on the growth of individual, single-crystal islands of the singlet fission material on the silicon surface. The islands have different heights, and we correlate these heights to the quenching efficiency of triplet excitons. The quenching efficiency is measured by spatially resolved delayed fluorescence and compared to a diffusion–quenching model. Using silicon capped with a blocking thermal oxide and aromatic monolayers, we demonstrate that this technique can quickly screen different silicon surface treatments for triplet exciton quenching. [ABSTRACT FROM AUTHOR]

Inspired by the homogeneous catalyst tris(pentafluorophenyl) borane [B(C6F5)3], which acts as a promotor of Si-H bond activation, we developed and studied a method of modifying silicon oxide surfaces using hydrosilanes with B(C6F5)3 as the catalyst. This dedihydrosiloxanation reaction yields complete surface coverage within 10 min at room temperature. Organic monolayers derived from hydrosilanes with varying carbon chain lengths (C8-C18) were prepared on oxidized Si(111) surfaces, and the thermal and hydrolytic stabilities of the obtained monolayers were investigated in acidic (pH 3) medium, basic (pH 11) medium, phosphate-buffered saline (PBS), and deionized water (neutral conditions) for up to 30 days. DFT calculations were carried out to gain insight into the mechanism, and the computational results support a mechanism involving silane activation with B(C6F5)3. This catalyzed reaction path proceeds through a low-barrier-height transition state compared to the noncatalyzed reaction path. [ABSTRACT FROM AUTHOR]

Starting from a chiral furanone, the nitrone-olefin [3 + 2] cycloaddition can be used to obtain bicyclic isoxazolidines for which we report a set of reactions to selectively modify each functional position. These synthetically versatile bicyclic isoxazolidines allowed us to obtain complex glycomimetic building blocks, like iminosugars, via multicomponent chemistry. For example, a library of 20 pipecolic acid derivatives, a recurring motif in various prescription drugs, could be obtained via a one-pot Staudinger/aza-Wittig/Ugi three-component reaction of a bicyclic isoxazolidine-derived azido-hemiacetal. Notably, specific pipecolic acids in this library were obtained via hydrolysis of an unique tricyclic imidate side product of the Ugi reaction. The azido-hemiacetal was also converted into an aza-C-glycoside iminosugar via an unprecendented one-pot Staudinger/aza-Wittig/Mannich reaction. [ABSTRACT FROM AUTHOR]

Ion channels, many expressed in insect neural and muscular systems, have drawn huge attention as primary targets of insecticides. With the recent technical breakthroughs in structural biology, especially in cryo‐electron microscopy (cryo‐EM), many new high‐resolution structures of ion channel targets, apo or in complex with insecticides, have been solved, shedding light on the molecular mechanism of action of the insecticides and resistance mutations. These structures also provide accurate templates for structure‐based insecticide screening and rational design. This review summarizes the recent progress in the structural studies of 5 ion channel families: the ryanodine receptor (RyR), the nicotinic acetylcholine receptor (nAChR), the voltage‐gated sodium channel (VGSC), the transient receptor potential (TRP) channel, and the ligand‐gated chloride channel (LGCC). We address the selectivity of the channel‐targeting insecticides by examining the conservation of key coordinating residues revealed by the structures. The possible resistance mechanisms are proposed based on the locations of the identified resistance mutations on the 3D structures of the target channels and their impacts on the binding of insecticides. Finally, we discuss how to develop "green" insecticides with a novel mode of action based on these high‐resolution structures to overcome the resistance. [ABSTRACT FROM AUTHOR]

The products of the SuFEx reaction between sulfonimidoyl fluorides and phenols, sulfonimidates, are shown to display dynamic covalent chemistry with other phenols. This reaction was shown to be enantiospecific, finished in minutes at room temperature in high yields, and useful for both asymmetric synthesis and sustainable polymer production. Its wide scope further extends the usefulness of SuFEx and related click chemistries. [ABSTRACT FROM AUTHOR]

The products of the SuFEx reaction between sulfonimidoyl fluorides and phenols, sulfonimidates, are shown to display dynamic covalent chemistry with other phenols. This reaction was shown to be enantiospecific, finished in minutes at room temperature in high yields, and useful for both asymmetric synthesis and sustainable polymer production. Its wide scope further extends the usefulness of SuFEx and related click chemistries. [ABSTRACT FROM AUTHOR]

A "rim‐differentiated" pillar[6]arene (RD‐P[6]) was obtained successfully, with the assistance of a dimeric silver trifluoroacetate template, among eight different constitutional isomers in a direct and regioselective manner. The solid‐state conformation of this macrocycle could switch from the 1,3,5‐alternate to a truly rim‐differentiated one upon guest inclusion. This highly symmetric RD‐P[6] not only hosts metal‐containing molecules inside its cavity, but also can form a pillar[6]arene‐C60 adduct through co‐crystallization on account of donor‐acceptor interactions. The development of synthetic strategies to desymmetrize pillararenes offers new opportunities for engineering complex molecular architectures and organic electronic materials. [ABSTRACT FROM AUTHOR]

A "rim‐differentiated" pillar[6]arene (RD‐P[6]) was obtained successfully, with the assistance of a dimeric silver trifluoroacetate template, among eight different constitutional isomers in a direct and regioselective manner. The solid‐state conformation of this macrocycle could switch from the 1,3,5‐alternate to a truly rim‐differentiated one upon guest inclusion. This highly symmetric RD‐P[6] not only hosts metal‐containing molecules inside its cavity, but also can form a pillar[6]arene‐C60 adduct through co‐crystallization on account of donor‐acceptor interactions. The development of synthetic strategies to desymmetrize pillararenes offers new opportunities for engineering complex molecular architectures and organic electronic materials. [ABSTRACT FROM AUTHOR]

We report how the combination of dynamic covalent imine bonds and coordination bonds in a single polymer material not only imparts enhanced stability to the final polymer, but also allows the material to be sensitive to a range of stimuli, offering more fine-grained control over its properties. [ABSTRACT FROM AUTHOR]

Surface modification of stainless steel (SS316L) to improve surface properties or durability is an important avenue of research, as SS316L is widely used in industry and science. We studied, therefore, the formation and stability of a series of organic monolayers on SS316L under industrially relevant conditions. These included acidic (pH 3), basic (pH 11), neutral (Milli-Q water), and physiological conditions [10 mM phosphate-buffered saline (PBS)], as well as dry heating (120 °C). SS316L was modified with alkylphosphonic acids of chain length (CH2)n with n varying between 3 and 18. While alkylphosphonic acids of all chain lengths formed self-assembled monolayers with hydrophobic properties, only monolayers of chain lengths 12-18 formed ordered monolayers, as evidenced by static water contact angle (SCA), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and infrared reflection absorption spectroscopy (IRRAS). A long-term stability study revealed the excellent stability of monolayers with chain lengths 12-18 for up to 30 days in acid, neutral, and physiological solutions, and for up to 7 days under dry heating. Under strong basic conditions a partial breakdown of the monolayer was observed, especially for the shorter chain lengths. Finally, the effect of multivalent surface attachment on monolayer stability was explored by means of a series of divalent bisphosphonic acids. [ABSTRACT FROM AUTHOR]

An on-line high-performance liquid chromatography (HPLC) method for the rapid and selective detection of boronic acids in complex mixtures was developed. After optimization experiments at an HPLC flow rate of 0.40 mL/min, the HPLC-separated analytes were mixed post-column with a solution of 75 μM alizarin and 0.1% triethylamine in acetonitrile, which was delivered at a flow rate of 0.60 mL/min. The reaction between alizarin and boronic acids occurred in a reaction coil of dimensions of 3.5 m × 0.25 mm at a temperature of 50 °C, resulting in fluorescent complexes that were detected as positive peaks by a fluorescence detector ( λ exc 469 nm and λ em 610 nm). The method enabled the selective detection of various boronic acids and derivatives, with a limit of detection of phenylboronic acid of 1.2 ng or 1 μM. It could successfully monitor the progress of two organic reactions involving boronic acid-containing compounds, and provided useful insights into the course of the reactions. [ABSTRACT FROM AUTHOR]

Oriented immobilization of antibodies using boronic acids shows a strong potential for improving immunoassay performance but is not yet widely used, possibly because of the difficulties encountered in its implementation. How to choose the boronic acid structure and how should it be attached to the surface? How to choose an antibody that will bind to the boronic acid? Under which conditions should the binding take place for an effective oriented antibody immobilization? How to make sure that the antibody stays on the surface? This tutorial review provides answers to these questions through analysis of the literature and personal suggestions, and thereby intends to facilitate the development of this promising antibody immobilization strategy. [ABSTRACT FROM AUTHOR]

Two series of discotic columnar liquid crystals were prepared and investigated, consisting of a triazine core to which three triphenylenes (HATs) are attached, connected via a flexible variable spacer containing a triazole group. The triphenylenes have five pentafluoropentyloxy tails or four pentafluoropentyloxy tails and one methoxy group. The compounds with four fluorinated tails on the HAT groups show a lamellar-columnar phase (Collam), whereas a compound with five fluorinated tails on the HAT groups shows a hexagonal-columnar (Colh) phase. Small differences in the steric properties and fluorophobic effects can therefore have a strong influence on the ordering of the molecules in the liquid crystalline phase. [ABSTRACT FROM PUBLISHER]

Two new series of columnar discotic liquid crystalline materials based on a tristriazolotriazine (TTT) core connected to three pendant hexyloxytriphenylene or pentafluoropentyloxytriphenylene groups via a flexible alkyl spacer are synthesised and investigated. It is found that the mesophase stability is very much dependent on the spacer length. For a short spacer length (propyl or butyl), Colhphases are found in which the disc-like moieties are randomly mixed in the columns. For one compound with a pentyl spacer and pentafluoropentyloxy tails on the triphenylene groups, a Colobphase is found in which the columns of triphenylenes and TTT moieties are separated. When the spacer is longer (hexyl), the liquid crystallinity is lost. The compounds with pentafluoropentyloxy tails on the triphenylene units have a higher thermal stability than those with hexyloxy tails. [ABSTRACT FROM AUTHOR]

[Display omitted] • Composition of Δ8-THC solutions converted from CBD by eight protocols was investigated. • Three orthogonal chromatographic methods were developed. • Distinct ESI and EI spectra towards five THC isomers were reported. • Multiple THC isomers were found in acid-treated CBD samples and Δ8-THC-infused edibles. Δ8-Tetrahydrocannabinol (Δ8-THC) is increasingly popular as a controversial substitute for Δ9-tetrahydrocannabinol (Δ9-THC) in cannabinoid-infused edibles. Δ8-THC is prepared from cannabidiol (CBD) by treatment with acids. Side products including Δ9-THC and other isomers that might end up in Δ8-THC edibles are less studied. In this paper, three orthogonal methods, namely reversed-phase (RP)-UHPLC-DAD/HRMS, normal-phase/argentation (silica-Ag(I))-HPLC-DAD/MS, and GC-FID/MS were developed for analysis of cannabinoid isomers, namely Δ8-THC, Δ9-THC, CBD, Δ8-iso-THC, Δ(4)8-iso-THC, and hydrated THC isomers. Eight acid-treated CBD mixtures contained various amounts of Δ8-THC (0–89%, w/w%), high levels of Δ9-THC (up to 49%), Δ8-isoTHC (up to 55%), Δ(4)8-iso-THC (up to 17%), and three hydrated THC isomers. Commercial Δ8-THC gummies were also analyzed, and issues like overclaimed Δ8-THC, excessive Δ9-THC, undeclared Δ8-iso-THC, and Δ(4)8-iso-THC were found. These findings highlight the urgency of improving regulations towards converting CBD to Δ8-THC for use as food ingredients. [ABSTRACT FROM AUTHOR]

In the study of glycosidases, a class of activity‐based probes (ABPs), that are carbocyclic mimics of natural carbohydrates and can covalently bind the enzyme, have proven to be useful tools. This type of ABP has however not yet been reported for sialidases, glycosidases involved in various important biological processes in both health and disease, which hydrolyse terminal sialic acids. Here we present our study towards the synthesis of a carbocyclic sialic acid suitable for conversion into ABPs. We developed a route starting from a chiral furanone that includes a key early stage nitrone [3+2] cycloaddition to install most of the chiral centres present in N‐acetylneuraminic acid. The final stereocentre is installed via a Barbier alkylation, after which a ring closing metathesis forms the pivotal carbocyclic intermediate. Due to challenges in the final stretch, we were not able to convert this intermediate into an N‐acetylneuraminic acid ABP. However, the work presented here still represents a versatile route to potential future carbocyclic sialic acid derivatives. [ABSTRACT FROM AUTHOR]

The synthesis and liquid crystalline properties of two novel series of triphenylenes with 4 or 5 pentafuoropentyloxy tails and 1 or 2 alkoxy tails of varying length are reported. All compounds form wide-range hexagonal columnar phases. The isotropisation temperatures and the corresponding enthalpy changes for the compounds with 4 or 5 fluorinated tails are higher than for the compounds with 6 alkoxy tails, and also higher than for compounds with 6 fluorinated tails. These results indicate that the best ordering is obtained for compounds with a mix of fluorinated and non-fluorinated tails. With increasing length of the alkyl tails in HAT compounds with 4 or 5 fluoroalkoxy tails, the isotropisation temperatures decrease and thed-spacings as observed by XRD increase. All fluoro-containing compounds have a strong tendency for spontaneous homeotropic alignment on surfaces, both hydrophilic and hydrophobic. [ABSTRACT FROM PUBLISHER]

[Display omitted] • Polymer brushes with systematically varied fluorine content were synthesized. • Excellent self-healing was observed for fluorine-free methacrylate polymer brushes. • Carboxylic acid moieties formed upon damage are stabilized in 'bulk' of the brush. • Interplay of polarity and steric irregularity effects potential of polymer brushes. Heavily fluorinated polymeric coatings are used by industry in the prevention of polymeric fouling. However, due to their potential toxicity and lack of durability, there is an increasing demand for sustainable alternatives. In this research, eleven polymer brushes with varying side chain lengths and degrees of fluorination have been developed, and their antifouling and self-healing performances have been compared. In all cases where damage was inflicted by a pH 3 solution, the coatings – including the non-fluorinated ones – showed full restoration of their contact angle upon placement in an oven at 120 °C, confirming the self-healing ability of this range of coatings. One coating, poly(C10-MAF0), was unharmed by the acidic conditions, hence no self-healing capability could be established. Investigation with four fluorescently labelled polymer solutions and confocal fluorescent microscopy confirmed that all coatings have antifouling properties towards organic polymers. The more heavily fluorinated polymer brushes performed better than the rest, and not the non-fluorinated but rather the singly fluorinated brushes showed the least antifouling capability. Determination of the critical surface tension confirmed this trend: the heavily fluorinated polymer brushes have the lowest critical surface tension, and the singly fluorinated polymer brushes have the highest. A lack of alignment of the side chains of the polymer brushes is the proposed reason for this, explaining the contrast with previously reported monolayer experiments. Finally, we explain why both fluorinated and non-fluorinated brushes display self-healing characteristics. [ABSTRACT FROM AUTHOR]

Novel methods to make synthetic chiral polymers are highly desirable given their potential in a rapidly increasing number of bio‐inspired applications. The enantiospecific sulfur–fluorine exchange (SuFEx) reaction of chiral di‐sulfonimidoyl fluorides (di‐SFs) with diphenols, was used to produce high‐molecular‐weight chiral polymers with configurational backbone chirality. The resulting new class of polymers, polysulfonimidates, can be efficiently produced via this step‐growth mechanism for a wide range of di‐SFs and diphenols, yielding MnPS up to 283 kDa with a typical dispersity Đ around 1.6. The optical activity of the resulting chiral polymers is largely due to the intrinsic asymmetry of the S atoms (configurational chirality). Finally, the enantiospecificity (ee>98 %) of the polymerization reaction was demonstrated by the degradation of a disulfide‐containing polysulfonimidate. This novel route towards configurational main‐chain chirality opens up new approaches towards tailor‐made chiral polymers with precisely defined properties. [ABSTRACT FROM AUTHOR]

Vectorial catalysis—controlling multi‐step reactions in a programmed sequence and by defined spatial localization in a microscale device—is an enticing goal in bio‐inspired catalysis research. However, translating concepts from natural cascade biocatalysis into artificial hierarchical chemical systems remains a challenge. Herein, we demonstrate integration of two different surface‐anchored nanometer‐sized metal–organic frameworks (MOFs) in a microfluidic device for modelling vectorial catalysis. Catalyst immobilization at defined sections along the microchannel and a two‐step cascade reaction was conducted with full conversion after 30 seconds and high turnover frequencies (TOF≈105 h−1). [ABSTRACT FROM AUTHOR]

Novel methods to make synthetic chiral polymers are highly desirable given their potential in a rapidly increasing number of bio‐inspired applications. The enantiospecific sulfur–fluorine exchange (SuFEx) reaction of chiral di‐sulfonimidoyl fluorides (di‐SFs) with diphenols, was used to produce high‐molecular‐weight chiral polymers with configurational backbone chirality. The resulting new class of polymers, polysulfonimidates, can be efficiently produced via this step‐growth mechanism for a wide range of di‐SFs and diphenols, yielding MnPS up to 283 kDa with a typical dispersity Đ around 1.6. The optical activity of the resulting chiral polymers is largely due to the intrinsic asymmetry of the S atoms (configurational chirality). Finally, the enantiospecificity (ee>98 %) of the polymerization reaction was demonstrated by the degradation of a disulfide‐containing polysulfonimidate. This novel route towards configurational main‐chain chirality opens up new approaches towards tailor‐made chiral polymers with precisely defined properties. [ABSTRACT FROM AUTHOR]

Vektorielle Katalyse – die Steuerung von mehrstufigen Reaktionen in einer programmierten Abfolge und durch definierte räumliche Lokalisierung in einem mikroskaligen Reaktor – ist ein grundlegendes Ziel in der bioinspirierten Katalyseforschung. Die Übertragung von Konzepten aus der natürlichen Kaskaden‐Biokatalyse zu künstlichen hierarchischen chemischen Systeme bleibt jedoch eine Herausforderung. Hier zeigen wir die Integration von zwei verschiedenen oberflächenverankerten, nanometergroßen metallorganischen Gerüsten (MOFs) in einem mikrofluidischen Reaktor zur Modellierung der vektoriellen Katalyse. Die Katalysatoren wurden an definierten Abschnitten entlang des Mikrokanals immobilisiert, dies ermöglichte eine zweistufige Kaskadenreaktion mit vollständiger Umsetzung nach 30 Sekunden und hohen Umsatzfrequenzen (TOF≈105 h−1). [ABSTRACT FROM AUTHOR]

It is of great significance to prepare supercapacitors with high energy density and high stability for their application. In this work, we demonstrate that PEDOT/PANI:(HSO 4 -) X :(CF 3 SO 3 -) 1-X composite electrodes obtained by in-situ polymerization and electrochemical polymerization with oriented nanorods structure can facilely assemble into flexible supercapacitors. An outstanding specific capacitance of 1042.7 F g−1 is achieved for PEDOT/PANI:(HSO 4 -) X :(CF 3 SO 3 -) 1-X composite electrode under the condition of 10 mV s−1 in 1 M H 2 SO 4 electrolyte. It is found that PANI grown on PEDOT has a rod-like structure with interpenetrating networks, which provides a high specific surface area and increased electron transmission channels. As a result, the specific capacitance of the assembled flexible supercapacitor reaches 361.6 F g−1, with 71 % capacitance retention after 10,000 cycles. The flexible supercapacitor delivers a high energy density of 28.5 mWh g−1 at a power density of 789.5 mW g−1. This work shows that PEDOT/PANI:(HSO 4 -) X :(CF 3 SO 3 -) 1-X composite electrode is a promising electrode material for flexible supercapacitors. [Display omitted] [ABSTRACT FROM AUTHOR]

Highlights: [•] A microfluidic chip with 3 parallel channels (feed/transport/acceptor) replaces two separate liquid–liquid-extraction (LLE) steps. [•] Butyl acetate as transport phase yields the best extraction for alkaloids. [•] Comparing to traditional LLE, microfluidic LLE shortens analysis time, saves labor and is environmentally friendly. [•] Hyphenation of the chip to nanoLC–UV/MS was successfully realized. [ABSTRACT FROM AUTHOR]