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Although tetraphenylethylene (TPE) and its derivatives have been the most commonly used building blocks in the construction of molecules with aggregation‐induced emission (AIE) properties, no absolute consensus exists regarding the mechanisms at the origin of the phenomenon. Restriction of intramolecular rotations (RIR) of peripheral phenyls has historically been a dominant paradigm, which has served as a valuable guideline in the molecular engineering of AIEgens. Yet, an increasing number of recent works have established that photoisomerization or photocyclization may actively participate in the nonradiative dissipation of the excitation energy. In this paper, the first experimental evaluation of the quantum efficiencies of these different processes is reported, and photoisomerization is shown to be by far the dominant photophysical pathway in solution, accounting for virtually all nonradiative decay of the molecule's excited state in degassed solution. [ABSTRACT FROM AUTHOR]

An external‐photocatalyst‐free, light‐driven alkylative ring‐opening of stable spiroindolines was developed to construct indolo‐ and benzoannulated eight‐membered lactams. The spiroindolines were prepared from tetrahydro‐β‐carbolines by a dearomative Heck reaction. Mechanistic experimental studies on the alkylative ring opening suggested that a photoredox pathway was involved, in which the spiroindoline performed as both reagent and photosensitizer. DFT calculations showed that the radical addition toward a cyclic alkene was the key to the diastereoselective formation of tetracyclic medium‐sized lactams. [ABSTRACT FROM AUTHOR]

2019, which was proclaimed by the United Nations as the International Year of the Periodic Table, sees one hundred years since Alfred Werner, the first Swiss to receive a Nobel Prize in chemistry, passed away. The undoubted father of coordination chemistry, he is also well‐known for influencing many other fields of chemistry, including organic, inorganic, organometallic, bioinorganic, and stereochemistry. However, one of his more rare and unique contributions to chemistry, his 1905 version of the periodic system, to this day remains overlooked. The simple and elegant idea which he used to construct his periodic table has not been communicated to the English‐speaking world, because Alfred Werner published his only original paper on the periodic table in German. Werner's simple mathematical approach lead to overwhelming success with anticipating the future f‐block. He managed to predict almost perfectly the number of lanthanides, which was hotly debated at that time. Werner's genius vision was considerably ahead of its time. It was not until the 1940s and the discovery of actinide series when the idea of representing the elements as a 32‐column periodic table finally became justified. [ABSTRACT FROM AUTHOR]

Abstract: Ionic porous organic polymers have attracted much attention due to their broad applications in catalysis, energy storage/conversion, proton conduction, etc. In this paper, an ionic porous organic polymer, CMP‐PM‐Me, was synthesized through post‐synthetic modification of a pyrimidine‐based conjugated microporous polymer, CMP‐PM, which was constructed by the palladium catalyzed Sonogashira reaction of 1,3,5‐triethynylbenzen and 2,5‐dibromopyrimidine. These two polymers are porous with Brunauer–Emmett–Teller surface areas of 416 and 241 m2 g−1 for CMP‐PM and CMP‐PM‐Me, respectively. Due to the cationic framework, CMP‐PM‐Me exhibits a much faster and more efficient adsorption performance to anionic dyes such as Congo red (CR) and methyl orange (MO) than that of CMP‐PM with a neutral framework. The uptakes for CR are 400.0 mg g−1 for CMP‐PM‐Me and 344.8 mg g−1 for CMP‐PM, respectively. Furthermore, CMP‐PM‐Me could quickly and drastically separate anionic dyes from the binary mixed solution of anionic and nonanionic dyes within a short time. This work not only enriches the family of ionic organic porous polymers and widens their synthetic utility, but also demonstrates their applications in the adsorption and separation of anionic dyes in water. [ABSTRACT FROM AUTHOR]

Abstract: Detection of nitroaromatics at ultralow concentration is a major security concern in defense, forensics, and environmental science. To this end, a new triarylamine‐cored dendritic gelator (OGR) was synthesized, which produced thermoreversible, thixotropic, and fluorescent gels in n‐octanol. On gelation, both π–π* transitions and the emission peak of the gelator show redshifts with a 4.5‐fold increase of fluorescence intensity in the gel state indicating J‐aggregation. The nitrogen lone‐pair electrons of OGR make it a donor, and electron transfer occurs to acceptor nitroaromatics causing fluorescence quenching, which is further promoted due to its acidity. The Stern–Volmer rate constants measured for different nitroaromatics showed that it senses picric acid (PA) best. The contact‐mode technique with OGR‐treated paper strips can allow naked‐eye detection of PA under UV light down to 10−11  m concentration within 30 s. Reusability of the gel is achieved by treating OGR@PAx with NaOH solution. Impedance spectroscopic results indicated a decrease of both charge‐transport resistance and Warburg impedance on successive addition of PA. The limits of detection of PA determined from fluorescence and impedance measurements match well. Thus, the OGR gel is a reusable, low‐cost, specific sensor for PA by naked‐eye colorimetric, fluorescence, and impedance techniques. [ABSTRACT FROM AUTHOR]

Metal organic frameworks (MOFs) are a class of porous organic-inorganic crystalline materials that have attracted much attention as H2 storage devices and catalytic supports. In this paper, the synthesis of highly-dispersed Ni nanoparticles (NPs) for the hydrogenation of olefins was achieved by employing Ni-MOF-74 as a precursor. Investigations of the structural transformation of Ni species derived from Ni-MOF-74 during heat treatment were conducted. The transformation was monitored in detail by a combination of XRD, in situ XAFS, and XPS measurements. Ni NPs prepared from Ni-MOF-74 were easily reduced by the generation of reducing gases accompanied by the decomposition of Ni- MOF-74 structures during heat treatment at over 300 °C under N2 flow. Ni-MOF-74-300 exhibited the highest activity for the hydrogenation of 1-octene due to efficient suppression of excess agglomerated Ni species during heat treatment. Moreover, Ni-MOF-74-300 showed not only high activity for the hydrogenation of olefins but also high size-selectivity because of the selective formation of Ni NPs covered by MOFs and the MOF-derived carbonaceous layer. [ABSTRACT FROM AUTHOR]

In the last decade, numerous studies of graphene doping by various metal and nonmetal elements have been done in order to obtain tailored properties, such as non-zero band gap, electrocatalytic activity, or controlled optical properties. From nonmetal elements, boron and nitrogen were the most studied dopants. Recently, it has been shown that in some cases the enhanced electrocatalytic activity of graphene and its derivatives can be attributed to metal impurities rather than to nonmetal elements. In this paper, we investigated the electrocatalytical properties of B/N codoped graphene with respect to the content of metallic impurities introduced by the synthesis procedures. For this purpose, a permanganate (Hummers) and a chlorate (Hofmann) route were used for the preparation of the starting graphene oxides (GO). The GO used for the synthesis of B/N codoped graphene had significantly difference compositions of oxygen functionalities as well as metallic impurities introduced by the different synthetic procedures. We performed a detailed structural and chemical analysis of the doped graphene samples to correlate their electrocatalytic activity with the concentration of incorporated boron and nitrogen as well as metallic impurities. [ABSTRACT FROM AUTHOR]

Freestanding metal nanoclusters can tune, precisely and effectively, the Gibbs free energy (ΔGH) of atomic hydrogen on the surface of materials. This enables the enhancement of hydrogen evolution activity. In this paper, we report a study of freestanding Pd-Ru distorted icosahedral clusters (ico-clusters) with less than 600 atoms by using a simple one-pot synthesis method. This Pd-Ru ico-cluster can be used as an efficient electrocatalyst for the hydrogen evolution reaction (HER) in acidic water, which is a promising alternative to Pt. The experimental and theoretical results suggest that the face-centered cubic (fcc) freestanding Pd-Ru distorted ico-clusters with less than 600 atoms ensure increased active edges and distorted defect sites, which reduce the coordination number for the atoms on the catalyst surface. Furthermore, Ru is a more effective hydrogen dissociation source, whereas Pd has a better hydrogen storage function. Pd-Ru can tune the ΔGH of atomic hydrogen adsorbed on a catalyst and reach an optimal equilibrium state that improves the HER performance. Our studies represent a robust approach towards the development of freestanding Pd-Ru distorted ico-clusters and advanced catalysts with non-Pt content for HER and many other heterogeneous reactions. [ABSTRACT FROM AUTHOR]

The paper by Gershoni-Poranne and Chen (R. Gershoni-Poranne, P. Chen, Chem. Eur. J. 2017, 23, 4659) gives an incorrect definition of covalent bonding. Furthermore, the assignment of so-called charge shift bonds in ammonium compounds has no physical foundation and is conceptually redundant. [ABSTRACT FROM AUTHOR]

As Liu et al. reported previously ( Appl. Mater. Today 2017, 7, 239-245), the charge transfer to partially oxidized polyaniline (PANI) nanotubes in electrochemical reactions is heavily limited due to the non-conductivity of the reduction/oxidation products. In this paper, the doping level of individual PANI nanotubes was substantially enhanced using nitrite as an electron acceptor in sulfuric acid aqueous solution as recorded by the nano-impact method. The charge transferred to one single tube during reduction process is close to the theoretical value of 170±112 pC per tube (assuming 2-electron reduction for the PANI tubes studied), while the charge during PANI oxidation is dramatically decreased. Reaction processes are proposed based on the oxidative properties of nitrite in acid solution. UV-visible spectroscopy analysis further confirms an oxidation-reduction reaction between PANI and nitrite. In contrast the electrochemical reaction of ensembles (21 μg cm−1) of PANI tubes on glassy carbon electrodes simply show limited electrocatalytic activity. [ABSTRACT FROM AUTHOR]

Controlling the shape of the conducting polymer-noble metal composites is a key factor in determining their properties and applications. In this paper, we demonstrate a novel strategy to fabricate Au-polypyrrole (PPy) composites with unusual morphology using poly(4-vinylpyridine) (P4VP) brush grafted on graphene oxide (GO) as a reaction chamber. When the GO/P4VP brush bearing AuCl4− ions is exposed to pyrrole vapor or directly immersed into pyrrole solution, novel Au−PPy nanotubules and flower-like Au mesoparticles-PPy composites are formed on the surface of GO/P4VP brush, respectively. The application of the as-prepared GO/P4VP/Au−PPy composites in catalysis and surface-enhanced Raman scattering (SERS) are investigated. The relevant results exhibit that the GO/P4VP/Au−PPy nanotubules can act as an efficient catalyst for reduction of 4-nitrophenol, and the GO/P4VP/flower-like Au mesoparticles-PPy composites can be used as a sensor platform for the detection of organic molecules by SERS. [ABSTRACT FROM AUTHOR]

Pentacene is one of the most versatile organic semiconductors. New synthetic strategies to construct the pentacene skeleton are imperative to produce pentacene derivatives with appropriate solubility, stability, and optoelectronic properties for various applications. This paper describes a template-directed approach to pentacene derivatives. In the retrosynthesis, the acene skeleton is viewed as a laddered double strand polyene instead of the more intuitive linearly fused hexagons. Based on this vision, the template strand of polyene is constructed with Wittig olefination, whereas the second strand is accomplished with Knoevenagel condensation to produce pentacene and tetracene derivatives. The synthetic scheme is flexible enough to generate an array of acene derivatives with substitution patterns that were hitherto difficult to access. Amphiphilic pentacene and tetracene derivatives were also synthesized by the template strategy. One pentacene based amphiphilic rod-coil molecule undergoes self-assembly to form helical wire structures that were visualized with TEM. [ABSTRACT FROM AUTHOR]

Recently, surface engineering of the indium tin oxide (ITO) electrode of sandwich-like organic electric memory devices was found to effectively improve their memory performances. However, there are few methods to modify the ITO substrates. In this paper, we have successfully prepared alkyltrichlorosilane self-assembled monolayers (SAMs) on ITO substrates, and resistive random access memory devices are fabricated on these surfaces. Compared to the unmodified ITO substrates, organic molecules (i.e., 2-((4-butylphenyl)amino)-4-((4-butylphenyl)iminio)-3-oxocyclobut-1-en-1-olate, SA-Bu) grown on these SAM-modified ITO substrates have rougher surface morphologies but a smaller mosaicity. The organic layer on the SAM-modified ITO further aged to eliminate the crystalline phase diversity. In consequence, the ternary memory yields are effectively improved to approximately 40-47 %. Our results suggest that the insertion of alkyltrichlorosilane self-assembled monolayers could be an efficient method to improve the performance of organic memory devices. [ABSTRACT FROM AUTHOR]

The large majority of TACA-based (TACA=Tumor-Associated Carbohydrate Antigens) antitumor vaccines target only one carbohydrate antigen, thereby often resulting in the incomplete destruction of cancer cells. However, the morphological heterogeneity of the tumor glycocalix, which is in constant evolution during malignant transformation, is a crucial point to consider in the design of vaccine candidates. In this paper, an efficient synthetic strategy based on orthogonal chemoselective ligations to prepare fully synthetic glycosylated cyclopeptide scaffolds grafted with both Tn and TF antigen analogues is reported. To evaluate their ability to be recognized as tumor antigens, direct interaction ELISA assays have been performed with the anti-Tn monoclonal antibody 9A7. Although both heterovalent structures showed binding capacities with 9A7, the presence of the second TF epitope did not interfere with the recognition of Tn except in one epitope arrangement. This heterovalent glycosylated structure thus represents an attractive epitope carrier to be further functionalized with T-cell peptide epitopes. [ABSTRACT FROM AUTHOR]

This paper reports on stereospecific coupling reactions between an η2-cyclopropene ligand and pyridine derivatives, which are preferred to alternative C−H bond activation reactions. The dicyclopropylzirconocene complex [Cp2Zr( c-C3H5)2] ( 1) eliminates cyclopropane to generate the η2-cyclopropene/bicyclobutane intermediate [Cp2Zr(η2- c-C3H4)] ( A). A does not activate any pyridine C−H bonds, but rather pyridine inserts into a Zr−C bond of A, yielding an azazirconacycle with a dearomatized pyridyl group [Cp2Zr{κ2-N,C8-(2- c-C3H4)-C5H5N}] ( 2). Kinetic data, isotopelabelling experiments, and DFT calculations indicate that the rate-determining step of this stereospecific reaction is cyclopropane elimination, and that the stability of the intermediate [Cp2Zr(η2- c-C3H4)(NC5H5)] ( A-py) governs the selectivity of the reaction. Complex 2 tautomerizes to [Cp2Zr{κ2-N,C8-(2-C3H5)-C5H4N}] ( 6) through a base-catalyzed proton migration accompanied by cyclopropyl opening and restoration of conjugation within the zirconacycle. [ABSTRACT FROM AUTHOR]

The detection of food spoilage is a major concern in food safety as large amounts of food are transported globally. Direct analysis of food samples is often time-consuming and requires expensive analytical instrumentation. A much simpler and more cost-effective method for monitoring food fermentation is to detect biogenic amines generated as a by-product during food decomposition. In this work, a series of 1,2-dihydroquinoxaline derivatives (DQs) with aggregation-induced emission (AIE) characteristics were synthesised and their protonated forms, that is, H+DQs, can be utilised for the sensitive detection of biogenic amines. For example, upon exposure to amine vapours, deprotonation occurs that converts the red-coloured, non-emissive H+DQ2 back to its yellow-coloured, fluorescent parent form. The bimodal absorption and emission changes endow the system with high sensitivity, capable of detecting ammonia vapour at a concentration of as low as 690 ppb. Taking advantage of this, H+DQ2 was successfully applied for the detection of food spoilage and was established as a robust and cost effective technique to monitor food safety. [ABSTRACT FROM AUTHOR]

Activation of anticancer therapeutics such as ruthenium (Ru) complexes is currently a topic of intense investigation. The success of phototherapy relies on photoactivation of therapeutics after the light passes through skin and tissue. In this paper, the photoactivation of anticancer Ru complexes with 671-nm red light through tissue of different thicknesses was studied. Four photoactivatable Ru complexes with different absorption wavelengths were synthesized. Two of them (Ru3 and Ru4) were responsive to wavelengths in the 'therapeutic window' (650-900 nm) and could be activated using 671-nm red light after passing through tissue up to 16-mm-thick. The other two (Ru1 and Ru2) could not be activated using red light. Additionally, activated Ru4 caused inhibition of cancer cells. These results suggest that photoactivatable Ru complexes are promising for applications in deep-tissue phototherapy. [ABSTRACT FROM AUTHOR]

Polyoxometalates (POM) have already been confirmed to act as effective electron-transfer mediators for improving the power conversion efficiency (PCE) of dye-sensitized solar cells (DSSCs) based on previous studies. However, the improvement may be limited by the agglomeration of the polyoxoanions. In this paper, the previous synthesis strategy is improved upon by breaking the metal-organic frameworks (MOFs) with POMs as the secondary building units ([Ni(bpp)(H2O)2]3[P2W18O62] ⋅24 H2O ( 1) (bpp=1,3-bis(4-pyridyl)propane) and H6[Cu3(H2O)6(P2W18O62)2(3-dpye)6] ⋅28 H2O ( 2) (3-dpye=N,N′-bis(3-pyridinecarboxamide)-1,2-ethane)) to design and synthesize small sized and highly disperse POM nanoparticles by means of compositing with TiO2, through calcination to remove the organic ligand. TEM and element mapping confirm that P2W18O626− (denoted as P2W18) nanoparticles with the diameter of ≈1 nm are uniformly distributed in TiO2 composites. The loading amount (wt. %) of POM in MOFs reaches 75.67 %. The small sized and highly disperse P2W18 nanoparticles may provide more active sites and specific surface areas for improving the PCE of DSSCs. Finally, the investigations indicate that the PCE of composite P2W18⋅NiO@TiO2 photoanodes is up to 7.56 %, which was 26 % higher than the pristine TiO2 based photoanodes. [ABSTRACT FROM AUTHOR]

A stable 3D TbIII-based metal-organic framework [Tb(BPDC)2]⋅(CH3)2NH2 (DUT-101) was synthesized, and it is the first efficient dual-channel luminescence sensor for aqueous UO22+ ions. DUT-101 contains an anionic three-dimensional framework and protonated dimethylamine molecules embedded within the channels. The intense green emission of DUT-101 could be highly selectively and sensitively quenched by UO22+ ions even in the presence of other competing metal ions. A possible sensing mechanism was proposed based on both suppression of luminescence resonance energy transfer and enhancement of intermolecular electron transfer. Furthermore, visual green fluorescent test papers based on DUT-101 were fabricated and could be used to discriminate UO22+ ions among various metal ions. [ABSTRACT FROM AUTHOR]

In view of their intensive use as ligands in many reactions catalyzed by transition-metal complexes, modulation of the bonding properties of N-heterocyclic carbenes (NHCs) on a rational basis is highly desirable, which should enable optimization of current applications or even promote new functions. In this paper, we provide a quantitative analysis of the chemical bond between a metal fragment AuCl and a series of 29 different NHCs in [(NHC)AuCl] complexes. NHCs electronic properties are modified through: i) variation of the groups attached to the NHC nitrogen atoms or backbone; ii) change of unsaturation/size of the NHC ring; iii) inclusion of paracyclophane moieties; or iv) heteroatom substitution on the NHC ring. For evaluating the donation and back-donation components of the Dewar-Chatt-Duncanson (DCD) model in the NHC−AuCl bond, we apply the charge-displacement (CD) analysis within the NOCV (natural orbitals for chemical valence) framework, a methodology that avoids the constraint of using symmetrized structures. We show that modulation of the NHC bonding properties requires substantial modification of their structure, such as, for instance, insertion of two ketone groups into the NHC backbone (which enhances the π back-donation bond component and introduces an effective electronic communication within the NHC ring) or replacement of a nitrogen atom in the ring with an sp3 or sp2 carbon atom (which increases and decreases the π back-donation bond component, respectively). We extend our investigation by quantitatively comparing the NHC electronic structures for a subset of 13 NHCs in [(NHC)PPh] adducts, the 31P NMR chemical shift values of which are experimentally available. The latter have been considered as a suitable tool for measuring the NHCs π acceptor properties [Bertrand et al., Angew. Chem. Int. Ed. 2013, 52, 2939-2943]. We show that information obtained using the metal fragment can be transferred to the PPh moiety and vice versa. However, the 31P NMR chemical shift values only qualitatively correlate with the π acceptor properties of the NHCs, with the stronger π acidic carbenes as the most outliners. [ABSTRACT FROM AUTHOR]

The design of new biocatalysts is a goal in biotechnology to improve the rate, selectivity and environmental impact of industrial chemical processes. In this regard, the use of computational techniques has provided valuable assistance in the design of new enzymes with remarkable catalytic activity. In this paper, hybrid QM/MM molecular dynamics simulations have allowed insights to be gained on the origin of the limited efficiency of a computationally designed enzyme for the Kemp elimination; the HG-3. Comparison of results derived from this enzyme with those of a more evolved protein containing additional point mutations, HG-3.17, rendered important information that should be taken into account in the design of new enzymes. For this Kemp eliminase reaction, higher reactivity has been demonstrated to be related to a better electrostatic preorganisation of an environment that creates a more favourable electrostatic potential for the reaction to proceed. The limitations of HG-3 can be related to a lack of flexibility, a not well-fitted active site, and a lack of protein electrostatic preorganisation, which decrease the reorganisation around the oxyanion hole. [ABSTRACT FROM AUTHOR]

The phosphanoxy‐substituted phosphaalkene bearing the P=C−O−P skeleton can be prepared from diphosphene Mes*P=PMes* (Mes*=2,4,6‐tBu3C6H2), and their use for catalysis is of interest. In this paper, complexation of the phosphanoxy‐substituted phosphaalkenes with gold are investigated, and the catalytic activity of the mono‐ and bis(chlorogold) complexes are subsequently evaluated. Reaction of the P=C−O−P compound with (tht)AuCl (tht=tetrahydrothiophene) showed dominant coordination on the sp3 phosphorus, and complete coordination on the sp2 phosphorus required removal of tetrahydrothiophene. Atoms In Molecules (AIM) analysis based on the X‐ray structure of the mono(chlorogold) complex indicated a pseudo coordinating interaction between the gold center and the P=C unit. The bis(chlorogold) complexes displayed conformational isomerism, and catalyzed the cycloisomerization/alkoxycyclization of 1,6‐enyne and for hydration of terminal alkyne without activation treatment. Even the mono(chlorogold) complexes catalyzed the alkoxycyclization reactions without a silver co‐catalyst, indicating that the alcohols were effective in activating the AuCl unit. [ABSTRACT FROM AUTHOR]

Natural Aquaporin (AQP) channels are efficient water translocating proteins, rejecting ions. Inspired by this masterpiece of nature, Artificial Water Channels (AWCs) with controlled functional structures, can be potentially used to mimic the AQPs to a certain extent, offering flexible avenues toward biomimetic membranes for water purification. The objective of this paper is to trace the historical development and significant advancements of current reported AWCs. Meanwhile, we attempt to reveal important structural insights and supramolecular self‐assembly principles governing the selective water transport mechanisms, toward innovative AWC‐based biomimetic membranes for desalination. [ABSTRACT FROM AUTHOR]

All studies on oxygen‐evolution reaction by Mn oxides in the presence of cerium(IV) ammonium nitrate (CAN) have been so far carried out by synthesizing Mn oxides in the first step. And then, followed by the investigation of the Mn oxides in the presence of oxidants for oxygen‐evolution reaction (OER). This paper presents a case study of a new and promising strategy for in situ catalyst synthesis by the adding MnII to either CAN or KMnO4/CAN solution, resulting in the formation of Mn‐based catalysts for OER. The catalysts were characterized by scanning electron microscopy, energy‐dispersive spectroscopy, transmission electron microscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, X‐ray absorption spectroscopy, and X‐ray photoelectron spectroscopy. Both compounds contained nano‐sized particles that catalyzed OER in the presence of CAN. The turnover frequencies for both catalysts were 0.02 (mmolO2 /molMn⋅s). [ABSTRACT FROM AUTHOR]

Azobenzene and its derivatives are one of the most widespread molecular scaffolds used in a range of modern applications, as well as in fundamental research. After photoexcitation, azo‐based photoswitches revert back to the most stable isomer on a timescale (t1/2) that determines the range of potential applications. Attempts to bring t1/2 to extreme values prompted the development of azobenzene and azoheteroarene derivatives that either rebalance the E‐ and Z‐isomer stabilities, or exploit unconventional thermal isomerization mechanisms. In the former case, one successful strategy has been the creation of macrocycle strain, which tends to impact the E/Z stability asymmetrically, and thus significantly modifyt1/2. On the bright side, bridged derivatives have shown an improved optical switching owing to the higher quantum yields and absence of degradation. However, in most (if not all) cases, bridged derivatives display a reversed thermal stability (more stable Z‐isomer), and smaller t1/2 than the acyclic counterparts, which restricts their potential interest to applications requiring a fast forward and backwards switch. In this paper, the impact of alkyl bridges on the thermal stability of phenyl‐azoheteroarenes is investigated by using computational methods, and it is revealed that it is indeed possible to combine such improved photoswitching characteristics while preserving the regular thermal stability (more stable E‐isomer), and increased t1/2 values under the appropriate connectivity and bridge length. [ABSTRACT FROM AUTHOR]

In this paper, we highlight the synthesis of a variety of primary phosphine‐boranes (RPH2⋅BH3) from the corresponding dichlorophosphines, simply by using Li[BH4] as reductant and provider of the BH3 protecting group. The method offers facile access not only to alkyl‐ and arylphosphine‐boranes, but also to aminophosphine‐boranes (R2NPH2⋅BH3) that are convenient building blocks but without the protecting BH3 moiety thermally labile and notoriously difficult to handle. The borane‐protected primary phosphines can be doubly deprotonated using n‐butyllithium to provide soluble phosphanediides Li2[RP⋅BH3] of which the phenyl‐derivative Li2[PhP⋅BH3] was structurally characterized in the solid state. [ABSTRACT FROM AUTHOR]

Hierarchical-structured nanotubular silica/titania hybrids incorporated with particle-size-controllable ultrafine rutile titania nanocrystallites were realized by deposition of ultrathin titania sandwiched silica gel films onto each nanofiber of natural cellulose substances (e.g., common commercial filter paper) and subsequent flame burning in air. The rapid flame burning transforms the initially amorphous titania into rutile phase titania, and the silica gel films suppress the crystallite growth of rutile titania, thereby achieving nano-precise size regulation of ultrafine rutile titania nanocrystallites densely embedded in the silica films of the nanotubes. The average diameters of these nanocrystallites are adjustable in a range of approximately 3.3-16.0 nm by a crystallite size increment rate of about 2.4 nm per titania deposition cycle. The silica films transfer the electrons activated by crystalline titania and generate catalytic reactive species at the outer surface. The size-tuned ultrafine rutile titania nanocrystallites distributed in the unique hierarchical networks significantly improve the photocatalytic performance of the rutile phase titania, thereby enabling a highly efficient photocatalytic degradation of the methylene blue dye under ultraviolet light irradiation, which is even superior to the pure anatase-titania-based materials. The facile stepwise size control of the rutile titania crystallites described here opens an effective pathway for the design and preparation of fine-nanostructured rutile phase titania materials to explore potential applications. [ABSTRACT FROM AUTHOR]

Go nano! Cubelike Pt nanowire superstructures supported on vertically aligned bamboo‐shaped carbon nanotubes (see the FESEM image) are used as electrocatalysts for fuel cells. They exhibit remarkably improved stability over the commercial Pt/C catalyst made of Pt nanoparticles on amorphous carbon. [ABSTRACT FROM AUTHOR]

Specifically amplifying the emission signals of optical probes in tumors is an effective way to improve the tumor‐imaging sensitivity and contrast. In this paper, the first case of dendron‐based fluorescence turn‐on probes mediated by a Förster resonance energy transfer (FRET) mechanism is reported. Dendrons up to the fourth generation with a hydrophilic oligo(ethylene glycol) scaffold are synthesized by a solid‐phase synthesis strategy, and show precise and defect‐free chemical structures. To construct the fluorescence turn‐on probe, one Cy5.5 molecule is conjugated to the focal of a G3 dendron through a robust linkage and eight Black Hole Quencher 3 (BHQ‐3) molecules are conjugated to its periphery through a PEG chain bearing a reductively cleavable disulfide linkage. By in vitro and in vivo experiments, it is demonstrated that the fluorescence of the dendron‐based probe can be activated effectively and rapidly in the reductive environments of tumor cells and tissues, and the probe thus exhibits amplified tumor signals and weak normal tissue signals. Compared with the reported nanoscale turn‐on probes, the dendron‐based probe has several significant advantages, such as well‐defined chemical structure, precisely controllable fluorophore/quencher conjugation sites and ratio, desirable chemical stability, and reproducible pharmacokinetic and pharmacological profiles, and is very promising in tumor detection. [ABSTRACT FROM AUTHOR]

We report the synthesis and late‐stage diversification of a new class of hetero‐buckybowl, BN‐embedded dibenzocorannulenes (B2N2‐DBCs). The synthesis is achieved via one‐shot halogenative borylation, comprising the nitrogen‐directed haloboration of alkyne and an intramolecular bora‐Friedel‐Crafts reaction, which provides BN‐embedded dibenzocorannulene possessing two bromo substituents (B2N2‐DBC‐Br). B2N2‐DBC‐Br undergoes diversification via coupling reactions to provide a variety of arylated derivatives (B2N2‐DBC‐R), exhibiting strong blue fluorescence. An organic light‐emitting diode (OLED) employing one of the derivatives as an emitter exhibited a high external quantum efficiency of 6.6 % and long operational lifetime of 907 h at an initial luminance of 1000 cd m−2, indicating the significant potential for the development of efficient and stable hetero‐buckybowl‐based OLED materials. [ABSTRACT FROM AUTHOR]

Freshwater production using solar‐driven interfacial evaporation is regarded as a green and sustainable strategy. The biggest barrier to practical deployment of solar desalination, however, continues to be the lack of options for renewable materials. Herein, we present a facile two‐step carbonization approach that is sustainable for developing innovative two‐dimensional (2D) molybdenum carbide (Mo2C) materials derived from carbonized fruit wastes. The resultant 2D Mo2C photothermal layer has an efficient water evaporation rate of 1.52 kg m−2 h−1 with a photothermal conversion efficiency of 94 % under one sun irradiation, which is among the best reported values so far. The broad solar absorption band, high specific surface area (555.1 m2 g−1) with large micro‐ and meso porosity, of the Mo2C photothermal layer are responsible for these outstanding results. The conversion of food wastes into valuable products, in this case MXene, can potentially inspire greener developments of advanced materials for solar water evaporator. [ABSTRACT FROM AUTHOR]

Herein, we propose a rational design strategy by introducing photoactive thienyl and pyridyl groups into an AIE‐active tetraarylethene skeleton to achieve highly efficient photochemistry‐activated fluorescence enhancement from dominantly photo‐physical aggregation‐induced emission behavior, and prove that such photoactivated fluorescence enhancement is perfectly suited for superstable photocontrollable dual‐mode patterning applications in both solution and solid matrix. It is found that the photoactivated fluorescence of designed AIEgen is attributed to the irreversible cyclized‐dehydrogenation reaction under UV irradiation, and the oxidation product has a brighter fluorescence in both solution and solid states owning to its rigid and planar structure. The overall transformation rate of the AIEgen from its opened form to dehydrogenated form is up to nearly 100 % in a short period of UV irradiation, and the fast transformation and the stable product of this photochemical reaction guarantees super stability of photocontrolled patterning, which can be applied in photoactivated dual‐mode patterning and advanced anti‐counterfeiting. [ABSTRACT FROM AUTHOR]

There is no experimental support for the conclusion by Coppens and Chen in a recent paper that the (HOMO–LUMO) band gaps in a series of FeII polyoxotitanate cages are in the range 1.43–1.59 eV. [ABSTRACT FROM AUTHOR]

This paper describes our efforts to design a Pd-catalyzed asymmetric prenylation of 3-substituted oxindoles that affords access to both the linear and reverse-prenylated products. Both 3-alkyl- and 3-aryloxindoles performed well under our optimized reaction conditions. The regiodivergent alkylation of monoterpene-derived electrophiles using this methodology was also investigated. The utility of this methodology in natural product synthesis was demonstrated through the efficient total syntheses of four Flustra alkaloids, which also allowed the absolute stereochemistry of the prenylated oxindole products to be assigned. Surprisingly, the same enantiomer of ligand produced linear and branched regioisomers of opposite chirality. [ABSTRACT FROM AUTHOR]

Nitrogen-doped porous carbon nanosheets were prepared from eucalyptus tree leaves by simply mixing the leaf powders with KHCO3 and subsequent carbonisation. Porous carbon nanosheets with a high specific surface area of 2133 m2 g−1 were obtained and applied as electrode materials for supercapacitors and lithium ion batteries. For supercapacitor applications, the porous carbon nanosheet electrode exhibited a supercapacitance of 372 F g−1 at a current density of 500 mA g−1 in 1 m H2SO4 aqueous electrolyte and excellent cycling stability over 15 000 cycles. In organic electrolyte, the nanosheet electrode showed a specific capacitance of 71 F g−1 at a current density of 2 Ag−1 and stable cycling performance. When applied as the anode material for lithium ion batteries, the as-prepared porous carbon nanosheets also demonstrated a high specific capacity of 819 mA h g−1 at a current density of 100 mA g−1, good rate capability, and stable cycling performance. The outstanding electrochemical performances for both supercapacitors and lithium ion batteries are derived from the large specific surface area, porous nanosheet structure and nitrogen doping effects. The strategy developed in this paper provides a novel route to utilise biomass-derived materials for low-cost energy storage systems. [ABSTRACT FROM AUTHOR]

Complexes of the general formula [IrCl(cod)(bdp-NHC-bdp′)] and [IrCl(cod)(bdp-NHC)] (bdp=bodipy=4,4-difluoro-4-bora-3a,4a-diaza- s-indacene, cod=1,5-cyclooctadiene) were synthesized. The substitution reaction of cod with two molecules of CO converts weakly fluorescent into strongly fluorescent complexes [IrCl(CO)2(bdp-NHC-bdp′)] and [IrCl(CO)2(bdp-NHC)]. Bdp and bdp' form a fluorescence resonance energy transfer (FRET) pair and the excitation of bdp leads to a strong emission from bdp' with a virtual Stokes shift of 98 nm. The fluorescence gain ( IFl[Ir(CO)2]]/ IFl[Ir(cod)]=1.7) upon reaction with CO in this complex is modest. To increase the fluorescence gain, the quenching capacity of the transition metal was improved by increasing the electron density at iridium. This was achieved by substituting the metal-bound chloride with an electron-rich thiolate RC6H4S. Depending on the nature of the R substituent in [Ir(SC6H4R)(cod)(bdp-NHC-bdp′)], an improved fluorescence gain in the cod/CO substitution reaction of up to 4.3 was observed and up to 26 (from gain=5) in [Ir(SC6H4R)(cod)(bdp-NHC)]. DFT calculations on closely related [Ir(SC6H4R)(cod)(bdp-NHC)] complexes indicate that a photoinduced electron transfer mechanism is the dominant quenching pathway for the iridium thiolates with R=COMe, CF3, Cl, H, Me, tBu, OMe, NEt2. The CO-responsive FRET complex was immobilized on paper, displaying a red fluorescent color upon exposure to CO. [ABSTRACT FROM AUTHOR]

Bacterial bioluminescence with continuous glow has been applied to the fields of environmental toxin monitoring, drug screening, and in vivo imaging. Nonetheless, the chemical form of the bacterial bioluminophore is still a bone of contention. Flavin mononucleotide (FMN), one of the light-emitting products, and 4a-hydroxy-5-hydro flavin mononucleotide (HFOH), an intermediate of the chemical reactions, have both been assumed candidates for the light emitter because they have similar molecular structures and fluorescence wavelengths. The latter is preferred in experiments and was assigned in our previous density functional study. HFOH displays weak fluorescence in solutions, but exhibits strong bioluminescence in the bacterial luciferase. FMN shows the opposite behavior; its fluorescence is quenched when it is bound to the luciferase. This is the first example of flavin fluorescence quenching observed in bioluminescent systems and is merely an observation, both the quenching mechanism and quencher are still unclear. Based on theoretical analysis of high-level quantum mechanics (QM), combined QM and molecular mechanics (QM/MM), and molecular dynamics (MD), this paper confirms that HFOH in its first singlet excited state is the bioluminophore of bacterial bioluminescence. More importantly, the computational results indicate that Tyr110 in the luciferase quenches the FMN fluorescence via an electron-transfer mechanism. [ABSTRACT FROM AUTHOR]

Liquid-crystalline ionic liquids (LCILs) are ordered materials that have untapped potential to be used as reaction media for synthetic chemistry. This paper investigates the potential for the ordered structures of LCILs to influence the stereochemical outcome of the Diels-Alder reaction between cyclopentadiene and methyl acrylate. The ratio of endo- to exo-product from this reaction was monitored for a range of ionic liquids (ILs) and LCILs. Comparison of the endo: exo ratios in these reactions as a function of cation, anion and liquid crystallinity of the reaction media, allowed for the effects of liquid crystallinity to be distinguished from anion effects or cation alkyl chain length effects. These data strongly suggest that the proportion of exo-product increases as the reaction media is changed from an isotropic IL to a LCIL. A detailed molecular dynamics (MD) study suggests that this effect is related to different hydrogen bonding interactions between the reaction media and the exo- and endo-transition states in solvents with layered, smectic ordering compared to those that are isotropic. [ABSTRACT FROM AUTHOR]

A new colorimetric and fluorogenic probe, based on a 3-formyl boron dipyrromethene (BODIPY) phenylhydrazone, for the sensitive and selective detection NO2 (g) has been prepared. The probe in solution experiences a remarkable hypsochromic shift of its absorption and fluorescence emission bands in the presence gaseous NO2 (g), leading to limits of detection of few ppb. The probe also works in the solid phase, adsorbed on filter paper strips, or chemically immobilized on the surface of silica nanoparticles, with limits of detection to the naked eye of about 0.5 ppm. [ABSTRACT FROM AUTHOR]

Keywords: BiVO4; charge carrier utilization; overall water splitting; photocatalysis; photoelectrocatalysis EN BiVO4 charge carrier utilization overall water splitting photocatalysis photoelectrocatalysis 1 1 1 11/10/22 20221107 NES 221107 The current research status of BiVO SB 4 sb -constituted photo(electro)catalytic systems for solar overall water splitting (OWS) is reviewed in this paper. BiVO4, charge carrier utilization, overall water splitting, photocatalysis, photoelectrocatalysis Herein, effective charge carrier utilization is illustrated as the mainline, in which charge separation, charge transfer and surface catalytic reaction are detailly summarized towards the construction of efficient solar OWS systems. [Extracted from the article]

Frontispiece: Muon Spin Rotation/Resonance ( SR) for Studying Radical Reactivity of Unsaturated Organophosphorus Compounds Keywords: isotope effect; muon; muonium; phosphorus; radicals EN isotope effect muon muonium phosphorus radicals 1 1 1 09/27/22 20220922 NES 220922 This paper overviews the muon spin rotation/resonance ( SR) studies of the phosphorus congeners of alkenes, anthracenes, and cyclobutane-1,3-diyls. Isotope effect, muon, muonium, phosphorus, radicals. [Extracted from the article]

The global demand for energy and the concerns over climate issues renders the development of alternative renewable energy sources such as hydrogen (H2) important. A high‐spin (hs) FeII complex with o‐phenylenediamine (opda) ligands, [FeII(opda)3]2+ (hs‐[6R]2+), was reported showing photochemical H2 evolution. In addition, a low‐spin (ls) [FeII(bqdi)3]2+ (bqdi: o‐benzoquinodiimine) (ls‐[0R]2+) formation by O2 oxidation of hs‐[6R]2+, accompanied by ligand‐based six‐proton and six‐electron transfer, revealed the potential of the complex with redox‐active ligands as a novel multiple‐proton and ‐electron storage material, albeit that the mechanism has not yet been understood. This paper reports that the oxidized ls‐[0R][PF6]2 can be reduced by hydrazine giving ls‐[FeII(opda)(bqdi)2][PF6]2 (ls‐[2R][PF6]2) and ls‐[FeII(opda)2(bqdi)][PF6]2 (ls‐[4R][PF6]2) with localized ligand‐based proton‐coupled mixed‐valence (LPMV) states. The first isolation and characterization of the key intermediates with LPMV states offer unprecedented molecular insights into the design of photoresponsive molecule‐based hydrogen‐storage materials. [ABSTRACT FROM AUTHOR]

This Full Paper reports the formation of silver (Ag) NPs within spatially resolved two‐component hydrogel beads, which combine a low‐molecular‐weight gelator (LMWG) DBS‐CONHNH2 and a polymer gelator (PG) calcium alginate. The AgNPs are formed through in situ reduction of AgI, with the resulting nanoparticle‐loaded gels being characterised in detail. The antibacterial activity of the nanocomposite gel beads was tested against two drug‐resistant bacterial strains, often associated with hospital‐acquired infections: vancomycin‐resistant Enterococcus faecium (VRE) and Pseudomonas aeruginosa (PA14), and the AgNP‐loaded gels showed good antimicrobial properties against both types of bacteria. It is suggested that the gel bead format of these AgNP‐loaded hybrid hydrogels makes them promising versatile materials for potential applications in orthopaedics or wound healing. [ABSTRACT FROM AUTHOR]

Polydopamine (PD) and melanin species are chemically complex systems, the formation and properties of which are incompletely understood. Inspired by the role of functional amyloids in melanin biosynthesis, this paper examines the influences of the supramolecular structure of amyloids on oxidative polymerization of dopamine. Kinetic analyses on the formation of PD species in the presence of hen egg white lysozyme (HEWL) fibers or soluble HEWL revealed that both forms gave rise to the total quantity of PD species, but the rate of their formation could be accelerated only by the amyloid form. PD species formed with HEWL fibers showed a morphology of bundled fibers, whereas those with soluble HEWL had a mesh‐like structure. Amyloid fibers of recombinant Pmel17 had properties similar to those of HEWL fibers in modulating PD formation. The results presented here suggest how nature designs functionality with an amyloid structure and can help understand and engineer chemistries of other functional amyloids. [ABSTRACT FROM AUTHOR]

Earth-abundant transition-metal-based catalysts for electrochemical water splitting are critical for sustainable energy schemes. In this work, we use a rational design method for the synthesis of ultrasmall and highly dispersed bimetallic CoMo carbide/oxide particles deposited on graphene oxide. Thermal conversion of the molecular precursors [H3PMo12O40], Co(OAc)2·4H2O and melamine in the presence of graphene oxide gives the mixed carbide/oxide (Co6Mo6C2/ Co2Mo3O8) nanoparticle composite deposited on highly dispersed, N,P-doped carbon. The resulting composite shows outstanding electrocatalytic water-splitting activity for both the oxygen evolution and hydrogen evolution reaction, and superior performance to reference samples including commercial 20% Pt/C & IrO2. Electrochemical and other materials analyses indicate that Co6Mo6C2 is the main active phase in the composite, and the N,P-doping of the carbon matrix increases the catalytic activity. The facile design could in principle be extended to multiple bimetallic catalyst classes by tuning of the molecular metal oxide precursor. [ABSTRACT FROM AUTHOR]

Trityl radicals (TAMs) have recently appeared as an alternative source of spin labels for measuring long distances in biological systems. Finland trityl radical (FTAM) served as the basis for this new generation of spin labels, but FTAM is rather lipophilic and susceptible to self‐aggregation, noncovalent binding with lipophilic sites of proteins, and noncovalent docking at the termini of duplex DNA. In this paper the very hydrophilic OX063 TAM with very low toxicity and little tendency for aggregation is used as the basis for a spin label. Human serum albumin (HSA) labeled with OX063 has an intense narrow line typical of TAM radicals in solution, whereas HSA labeled with FTAM shows broad lines and extensive aggregation. In pulse EPR measurements, the measured phase memory time TM for HSA labeled with OX063 is 6.3 μs at 50 K, the longest yet obtained with a TAM‐based spin label. The lowered lipophilicity also decreases side products in the labeling reaction. [ABSTRACT FROM AUTHOR]

There has been a recent upsurge in the study and application of approaches utilizing cyclotriphosphate 1 (cyclo‐TP, also known as trimetaphosphate, TMP) and/or proceeding through its analogues in synthetic chemistry to access modified oligo‐ and polyphosphates. This is especially useful in the area of chemical nucleotide synthesis, but by no means restricted to it. Enabled by new high yielding and easy‐to‐implement methodologies, these approaches promise to open up an area of research that has previously been underappreciated. Additionally, refinements of concepts of prebiotic phosphorylation chemistry have been disclosed that ultimately rely on cyclo‐TP 1 as a precursor, placing it as a potentially central compound in the emergence of life. Given the importance of such concepts for our understanding of prebiotic chemistry in combination with the need to readily access modified polyphosphates for structural and biological studies, this paper will discuss selected recent developments in the field of cyclo‐TP chemistry, briefly touch on ultraphosphate chemistry, and highlight areas in which further developments can be expected. [ABSTRACT FROM AUTHOR]