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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.

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.

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.

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. Catalysts 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 = ~10 5 h -1 ).

Surface modifications using responsive polymers give access to biomedical applications that rely on switchable properties, such as smart sensors and actuator systems. In this work, thermoresponsive polymer coatings are synthesized on silicon oxide surfaces using a facile and effective two-step grafting-to strategy. Briefly, the substrates are first functionalized with a poly(dopamine) (poly(DA)) primer layer. Subsequently, block copolymers of poly(glycidyl methacrylate) and poly(N-isopropylacrylamide) (poly(GMA)20-block-poly(NIPAM)n (n = 263, 528 and 705)) synthesized via reversible addition‑fragmentation chain‑transfer (RAFT) polymerization, are grafted to the poly(DA)-modified surfaces. Characterization using ellipsometry, X-ray photoelectron spectroscopy (XPS) and contact angle measurements confirmed polymer attachment with appreciable grafting densities. Quartz crystal microbalance with dissipation monitoring (QCM-D) is employed to investigate the thermoresponsive properties and degree of hydration of the polymers below and above their lower critical solution temperature (LCST). The longer the polymer chain, the more water is lost per repeating unit upon increasing the temperature above the LCST. The surfaces are exposed to diluted and undiluted human serum at 20 °C and 40 °C to demonstrate for all three polymer brushes switchable protein adsorption-repellence. In a broader perspective, this study presents a straightforward, robust and efficient procedure to modify virtually any surface type with a thermoresponsive coating.

The constraints of minute reactant amounts and the impossibility to remove any undesired surface‐bound products during monolayer functionalization of a surface necessitate the selection of efficient, modular and orthogonal reactions that lead to quantitative conversions. Herein, we explore the character of sulfur–fluoride exchange (SuFEx) reactions on a surface, and explore the applicability for quantitative and orthogonal surface functionalization. To this end, we demonstrate the use of ethenesulfonyl fluoride (ESF) as an efficient SuFEx linker for creating “SuFEx‐able” monolayer surfaces, enabling three distinct approaches to utilize SuFEx chemistry on a surface. The first approach relies on a di‐SuFEx loading allowing dual functionalization with a nucleophile, while the two latter approaches focus on dual (CuAAC–SuFEx/SPOCQ–SuFEx) click platforms. The resultant strategies allow facile attachment of two different substrates sequentially on the same platform. Along the way we also demonstrate the Michael addition of ethenesulfonyl fluoride to be a quantitative surface‐bound reaction, indicating significant promise in materials science for this reaction.

Surface-initiated photoinduced electron-transfer-reversible addition–fragmentation chain transfer (SI-PET-RAFT) is, for the first time, used for the creation of antifouling polymer brushes on gold surfaces based on three monomers: oligo(ethylene glycol) methyl ether methacrylate (MeOEGMA), N-(2-hydroxypropyl) methacrylamide (HPMA), and carboxybetaine methacrylamide (CBMA). These coatings are subsequently characterized by X-ray photoelectron spectroscopy (XPS) and ellipsometry. The living nature of this polymerization allows for the creation of random and diblock copolymer brushes, which are based on HPMA (superb antifouling) and CBMA (good antifouling and functionalizable via activated ester chemistry). The polymer brushes demonstrate good antifouling properties against undiluted human serum, as monitored by quartz crystal microbalance with dissipation (QCM-D) and surface plasmon resonance (SPR) spectroscopy in real time. The amount of immobilization of bioactive moieties, here an antibody immobilized using N-succinimidyl ester–1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (NHS–EDC) coupling, in the diblock and random copolymer brushes is monitored by SPR, and is analyzed with respect to the brush structure, and is shown to be superior in the diblock copolymer brush. This approach represents a scalable, robust, mild, oxygen-tolerant, and heavy-metal-free route toward the production of antifouling and functional copolymer brushes (on gold surfaces) that open up applications in biosensing and tissue engineering.

Laccase‐mediated grafting on lignocelluloses has gained considerable attention as an environmentally benign method to covalently modify wood, paper and cork. In recent decades this technique has also been employed to modify fibres with a polysaccharide backbone, such as cellulose or chitosan, to infer colouration, antimicrobial activity or antioxidant activity to the material. The scope of this approach has been further widened by researchers, who apply mediators or high redox potential laccases and those that modify synthetic polymers and proteins. In all cases, the methodology relies on one‐ or two‐electron oxidation of the surface functional groups or of the graftable molecule in solution. However, similar results can very often be achieved through simple deposition, even after extensive washing. This unintended adsorption of the active substance could have an adverse effect on the durability of the applied coating. Differentiating between actual covalent binding and adsorption is therefore essential, but proves to be challenging. This review not only covers excellent research on the topic of laccase‐mediated grafting over the last five to ten years, but also provides a critical comparison to highlight either the lack or presence of compelling evidence for covalent grafting.

Strain‐promoted oxidation‐controlled cyclooctyne‐1,2‐quinone cycloaddition (SPOCQ) between functionalized bicyclo[6.1.0]non‐4‐yne (BCN) and surface‐bound quinones revealed an unprecedented 100 % conjugation efficiency. In addition, monitoring by direct analysis in real time mass spectrometry (DART‐MS) revealed the underlying kinetics and activation parameters of this immobilization process in dependence on its microenvironment.

Die Modifizierung von Oberflachen durch robuste Abscheidung einer Deckschicht bietet eine hervorragende Moglichkeit, die Eigenschaften eines sterisch anspruchsvollen Substrats auf die eigenen Interessen abzustimmen. Eine solche Kontrolle uber die Oberflacheneigenschaften gewinnt immer mehr an Bedeutung mit der stetigen Verkleinerung aktiver Bestandteile in allen moglichen optoelektronischen Geraten ebenso wie mit dem entsprechend groseren Oberflache/Volumen-Verhaltnis. Eine relevante einzustellende Eigenschaft ist z. B. das Ausmas, in dem eine Oberflache durch Wasser oder Ol benetzt wird. Zudem besteht fur Anwendungen in der Biosensorik ein wachsendes Interesse an “romantischen Oberflachen” – Oberflachen, die alle moglichen biologischen Entitaten abweisen, mit einer Ausnahme, die von ihnen stark gebunden wird. Solche Systeme erfordern eine nachhaltige wie auch hochspezifische Einstellung der Oberflacheneigenschaften. Dieser Aufsatz erlautert eine Vorgehensweise fur die Herstellung widerstandsfahiger Oberflachenmodifikationen an Oxiden, namlich die kovalente Anbindung von Monoschichten.

Piperazine is a widely studied solvent for post-combustion carbon dioxide capture. To investigate the possibilities of further improving this process, the electronic and steric effects of -CH(3), -CH(2)F, -CH(2)OH, -CH(2)NH(2), -COCH3 , and -CN groups of 2,5-disubstituted piperazines on the pKa and carbamate stability towards hydrolysis are investigated by quantum chemical methods. For the calculations, B3LYP, M11L, and spin-component-scaled MP2 (SCS-MP2) methods are used and coupled with the SMD solvation model. The experimental pK(a) values of piperazine, 2-methylpiperazine, and 2,5-dimethylpiperazine agree well with the calculated values. The present study indicates that substitution of -CH(3), -CH(2) NH(2), and -CH(2) OH groups on the 2- and 5-positions of piperazine has a positive impact on the CO(2) absorption capacity by reducing the carbamate stability towards hydrolysis. Furthermore, their higher boiling points, relative to piperazine itself, will lead to a reduction of volatility-related losses.

Second-order reaction kinetics of known strain-promoted azide–alkyne cycloaddition (SPAAC) reactions were compared with theoretical data from a range of ab initio methods. This produced both detailed insights into the factors determining the reaction rates and two straightforward theoretical tools that can be used to predict a priori the reaction kinetics of novel cyclooctynes for strain-promoted cycloaddition reactions. Multiple structural and electronic effects contribute to the reactivity of various cyclooctynes. It is therefore hard to relate a physical or electronic property directly and independently to the reactivity of the cyclooctyne. However, we show that Hartree–Fock LUMO energies, which were acquired while calculating activation energies at the MP2 level of theory, correlate with second-order kinetic rate data and are therefore usable for reactivity predictions of cyclooctynes towards azides. Using this correlation, we developed a simple theoretical tool that can be used to predict the reaction kinetics of (novel) cyclooctynes for SPAAC reactions.

The pKa of the conjugate acids of alkanolamines, neurotransmitters, alkaloid drugs and nucleotide bases are calculated with density functional methods (B3LYP, M08-HX and M11-L) and ab initio methods (SCS-MP2, G3). Implicit solvent effects are included with a conductor-like polarizable continuum model (CPCM) and universal solvation models (SMD, SM8). G3, SCS-MP2 and M11-L methods coupled with SMD and SM8 solvation models perform well for alkanolamines with mean unsigned errors below 0.20 pKa units, in all cases. Extending this method to the pKa calculation of 35 nitrogen-containing compounds spanning 12 pKa units showed an excellent correlation between experimental and computational pKa values of these 35 amines with the computationally low-cost SM8/M11-L density functional approach.

A new masked aldehyde-containing nitrone 1 that is easily available through a facile one-step procedure has been developed. It undergoes a [3 + 2]-thermal cycloaddition with a wide range of dipolarophiles, affording isoxazolidine cycloadducts that are suitable for versatile postcycloaddition modifications. The acetal cycloadducts are acid-stable, but allow for acetal hydrolysis under mildly basic conditions. The isoxazolidine ring can be opened via an efficient one-pot procedure to give amine-protected γ-alcohols that can be further converted to furanose derivatives.

The photothermal laser patterning of functional organic monolayers, prepared on oxide-free hydrogen-terminated silicon, and subsequent backfilling of the laser-written lines with a second organic monolayer that differs in its terminal functionality, is described. Since the thermal monolayer decomposition process is highly nonlinear in the applied laser power density, subwavelength patterning of the organic monolayers is feasible. After photothermal laser patterning of hexadecenyl monolayers, the lines freed up by the laser are backfilled with functional acid fluoride monolayers. Coupling of cysteamine to the acid fluoride groups and subsequent attachment of Au nanoparticles allows easy characterization of the functional lines by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Depending on the laser power and writing speed, functional lines with widths between 1.1 μm and 250 nm can be created. In addition, trifluoroethyl-terminated (TFE) monolayers are also patterned. Subsequently, the decomposed lines are backfilled with a nonfunctional hexadecenyl monolayer, the TFE stripes are converted into thiol stripes, and then finally covered with Au nanoparticles. By reducing the lateral distance between the laser lines, Au-nanoparticle stripes with widths close to 100 nm are obtained. Finally, in view of the great potential of this type of monolayer in the field of biosensing, the ease of fabricating biofunctional patterns is demonstrated by covalent binding of fluorescently labeled oligo-DNA to acid-fluoride-backfilled laser lines, which--as shown by fluorescence microscopy--is accessible for hybridization.

Herein, the influence of silicon surface modification via Si-C(n)H(2n+1) (n=10,12,16,22) monolayer-based devices on p-type 100 and n-type 100 silicon is studied by forming MIS (metal-insulator-semiconductor) diodes using a mercury probe. From current density-voltage (J-V) and capacitance-voltage (C-V) measurements, the relevant parameters describing the electrical behavior of these diodes are derived, such as the diode ideality factor, the effective barrier height, the flatband voltage, the barrier height, the monolayer dielectric constant, the tunneling attenuation factor, and the fixed charge density (Nf). It is shown that the J-V behavior of our MIS structures could be precisely tuned via the monolayer thickness. The use of n-type silicon resulted in lower diode ideality factors as compared to p-type silicon. A similar flatband voltage, independent of monolayer thickness, was found, indicating similar properties for all silicon-monolayer interfaces. An exception was the C10-based monolayer device on p-type silicon. Furthermore, low values of N(f) were found for monolayers on p-type silicon (approximately 6 x 10(11) cm(-2)). These results suggest that Si--C linked monolayers on flat silicon may be a viable material for future electronic devices.

The modification of surfaces by the deposition of a robust overlayer provides an excellent handle with which to tune the properties of a bulk substrate to those of interest. Such control over the surface properties becomes increasingly important with the continuing efforts at down-sizing the active components in optoelectronic devices, and the corresponding increase in the surface area/volume ratio. Relevant properties to tune include the degree to which a surface is wetted by water or oil. Analogously, for biosensing applications there is an increasing interest in so-called “romantic surfaces”: surfaces that repel all biological entities, apart from one, to which it binds strongly. Such systems require both long lasting and highly specific tuning of the surface properties. This Review presents one approach to obtain robust surface modifications of the surface of oxides, namely the covalent attachment of monolayers.

Covalent attachment of functionalized monolayers onto silicon surfaces (see Figure for examples) is presented here as a strategy for surface modification. The preparation and structure of both unfunctionalized and functionalized alkyl-based monolayers are described, as are potential applications, for example, in the surface passivation of Si solar cells and for photopatterning of silicon surfaces.

A Micelle-enhanced ultrafiltration (MEUF) separation process was investigated that can potentially be used for large-scale enantioseparations. Copper(II)-amino acid derivatives dissolved in nonionic surfactant micelles were used as chiral selectors for the separation of dilute racemic amino acids solutions. For the α-amino acids phenylalanine, phenylglycine, O- methyltyrosine, isoleucine, and leucine good separation was obtained using cholesteryl L-glutamate and Cu(II) ions as chiral selector with an operational enantioselectivity (α(op)) up to 14.5 for phenylglycine. From a wide set of substrates, including four β-amino acids, it was concluded that the performance of this system is determined by two factors: the hydrophobicity of the racemic amino acid, which results in a partitioning of the racemic amino acid over micelle and aqueous solution, and the stability of the diastereomeric complex formed upon binding of the amino acid with the chiral selector. The chiral hydrophobic cholesteryl anchor of the chiral selector also plays an active role in the recognition process, since inversion of the chirality of the glutamate does not yield the reciprocal enantioselectivities. However, if the cholesteryl group is replaced by a nonchiral alkyl chain, reciprocal operational enantioselectivities are found with enantiomeric glutamate selectors

A methodology has been developed for an efficient and selective lipase-catalyzed aza-Michael reaction of various amines (primary and secondary) with a series of acrylates and alkylacrylates. Reaction parameters were tuned, and under the optimal conditions it was found that Pseudomonas stutzeri lipase and Chromobacterium viscosum lipase showed the highest selectivity for the aza-Michael addition to substituted alkyl acrylates. For the first time also, some CLEAs were examined that showed a comparable or higher selectivity and yield than the free enzymes and other formulations.

Organic monolayers or polymer brushes, often in combination with surface structuring, are widely used to prevent nonspecific adsorption of polymeric or biological material on sensor and microfluidic surfaces. Here it is demonstrated for the first time how robust, covalently attached alkyne-derived monolayers with a varying numbers of fluorine atoms, on atomically flat Si(111), effectively repel a wide range of apolar polymers without the need for micro- or nanostructuring of the surface. The antifouling property of fluoro-hydro monolayers is studied for a range of commonly used polymers with comparable molecular weight in nonaqueous solvent. Also, the effect of polymer molecular weight on the fouling behavior is investigated. A surface morphology survey by atomic force microscopy characterization that can accurately quantify the degree of fouling is developed. It is observed that especially the monofluorinated (F1) alkyne-derived monolayer shows excellent antifouling behavior, under certain conditions even more so than corresponding monolayers with perfluorinated alkyl tails. The explanation of this surprising behavior is based on a competition of solvent–solute–surface interactions. These findings and analysis offer significant potential for antifouling applications of ultrathin and covalently bound fluorine-containing coatings for a range of micro- and nanotechnological applications.

The aromatic odd-alternant phenalenyl anion and a number of its derivatives were prepared in order to study the perturbation of this conjugated anion by methyl and methoxy groups. The conjugated anions were studied by means of 1H and 13C NMR spectrometry, alkylation experiments and semi-empirical calculations. It was found that a substituent at a charged carbon atom perturbs the entire conjugated system, whereas substituents at inactive (uncharged) carbon atoms have a large effect on the positions ortho to the substituent.

The syntheses of nine mononitro derivatives of aceanthrylene (1) and nine mononitro derivatives of aceanthrene (2) are described. In addition to 1 and 2, 1,2,6,10b-tetrahydroaceanthrylene (3), 6,10b-dihydro-2(1H)-aceanthrylenone (5), 1(2H)-aceanthrylenone (4) and 2(1H)-aceanthrylenone (8) were also used as starting materials. The resulting nitroaceanthrylenes and nitroaceanthrenes were characterized by their 1H-NMR, 13C-NMR, UV-VIS, IR and mass spectra. The conformation of the nitro group and the interaction between the nitro group and the aromatic system are discussed. In 2-nitroaceanthrylene (1b), the nitro group interacts exceptionally well with the aromatic nucleus. The 3-, 4-, 8- and 9-nitro derivatives of 1 and 2 display all the characteristics of normally conjugated planar nitroaromatic compounds. In the remaining nitro derivatives of 1 and 2, conjugation is diminished owing to steric interactions with nearby protons. The order of decreasing conjugation and increasing twist angle is 5-nitro > 7-nitro > 6-nitro > 10-nitro. The twist angle of the nitro group was calculated using semi-empirical SCF methods PM3 and AM1. Although the values obtained by these methods deviate substantially, they both give the same order of increasing twist angles as the spectroscopically derived order.

The syntheses of nine mononitro derivatives of aceanthrylene (1) and nine mononitro derivatives of aceanthrene (2) are described. In addition to 1 and 2, 1,2,6,10b-tetrahydroaceanthrylene (3), 6,10b-dihydro-2(1H)-aceanthrylenone (5), 1(2H)-aceanthrylenone (4) and 2(1H)-aceanthrylenone (8) were also used as starting materials. The resulting nitroaceanthrylenes and nitroaceanthrenes were characterized by their 1H-NMR, 13C-NMR, UV-VIS, IR and mass spectra. The conformation of the nitro group and the interaction between the nitro group and the aromatic system are discussed. In 2-nitroaceanthrylene (1b), the nitro group interacts exceptionally well with the aromatic nucleus. The 3-, 4-, 8- and 9-nitro derivatives of 1 and 2 display all the characteristics of normally conjugated planar nitroaromatic compounds. In the remaining nitro derivatives of 1 and 2, conjugation is diminished owing to steric interactions with nearby protons. The order of decreasing conjugation and increasing twist angle is 5-nitro > 7-nitro > 6-nitro > 10-nitro. The twist angle of the nitro group was calculated using semi-empirical SCF methods PM3 and AM1. Although the values obtained by these methods deviate substantially, they both give the same order of increasing twist angles as the spectroscopically derived order.

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 s-selectivity